Strategies for China’s Historic Districts Regeneration in Responding to Public Health Emergencies

Abstract

Most of China’s historic districts are located in urban centers with excessive building density and possess rich historical, cultural, scientific and aesthetic value. However, historic districts lack infrastructure and specific plans for emergency response compared to modern residential areas in cities, creating a social inequity trap for the residents in both. In addition, as valuable material cultural heritage, the usual conservation of local culture and the ecological environment conflict with anti-epidemic requirements. This study proposes a system of strategies for responding to public health emergencies that can address the above issues. Through the methods of policy refinement and the application of the concept of normal and disaster time conversion, the strategic system was constructed, including five major aspects: emergency preparedness programs at the planning level, installation of modulized variable devices, environmentally friendly health protection, disaster prevention preparation at the spatial level, and plant configuration. It is beneficial to improve the disaster prevention system for special urban communities and provide a reference for emergency planning in the future regeneration process of historic districts.

1. Introduction

The industrial revolution transformed the economic and social structure, leading to modernization and urbanization. Urban sprawl and urban regeneration are the main means [1] by which most countries around the world have addressed the problems of population expansion, housing constraints, and resource shortages associated with the process of urbanization. Endless urban expansion is not desirable for the sustainable development of most cities [2], so urban regeneration has become crucial [3]. Most of China’s historic districts are located in urban centers and accompany the entire development process of the city. The patterns of the older historic districts date back to the 13th century (Tang Dynasty). They contain high material and spiritual value, making China’s historic districts different from ordinary ones. For this reason, the conservation and development of historic districts are important topics.

In 2020, the COVID-19 pandemic posed a huge challenge to all aspects of the economy, society, and medical care in countries and cities around the world [4]. More and more people are rethinking and refocusing the direction of urban development in relation to public health events [5] and exploring themes related to human health and well-being.

Since the interiors of Chinese historic districts often have historic narrow streets and high-density building clusters, it is difficult to incorporate modern infrastructure for disaster. The characteristics of the historic districts allow for more frequent movement of people in historic districts, causing rapid expansion of the impact of public health emergencies [6]. This gives historic districts obvious risks and limitations when responding to public health emergencies. At the same time, the current legal regulations for responding to public health emergencies in China are not sufficiently detailed, and historic districts, as a special type of space in cities, lack corresponding emergency response plans. On the contrary, modern residential areas with better infrastructure also have better emergency response plans and clear management personnel, which can better meet the requirements of emergency response. These problems create social inequities between residents in historic districts and those in modern residential areas. Such circumstances have inspired scholars and managers to think about how historic districts can respond to the needs of residents in urban regeneration.

Due to the historical and cultural value of historic districts, policies and regulations related to their conservation have been increasingly improved. The spatial patterns and building clusters in historic districts are explicitly protected as cultural heritage of material space, leaving the installation of sites and facilities for disaster in historic districts neglected. Since the occurrence of COVID-19, it is naturally difficult to meet the huge modern emergency response needs in historic districts with hundreds of years of history. At the same time, the use of some epidemic control means, such as the extensive use of disinfectants, may affect the ecological and environmental protection of the historic districts. There is an obvious conflict between the usual conservation of historic districts and emergency response.

The COVID-19 pandemic continues to occur worldwide and affects the normal life of the population. The main problems of China’s historic districts in the response to COVID-19 are (1) the lack of necessary infrastructure for disaster, (2) no special response plan, (3) conflicts between the usual local cultural preservation and needs of emergency response, and (4) conflicts between the ecological environmental protection and anti-epidemic means. However, current literature and practice indicate that China lacks research on disaster infrastructure and emergency response plans for historic districts. In addition, there is a lack of measures to address the conflict between historic district conservation and emergency response. These concerns can lead to residents in historic districts not enjoying the same social equity as those in modern residential areas in the event of a public health emergency, as well as an imbalance between historic district conservation and emergency response.

In this context, the main objectives of this study are (1) addressing the inequities between residents of historic districts and modern urban residential areas and (2) balancing the relationship between historic district conservation and emergency response. By accomplishing these objectives, historic districts can respond effectively to public health events and reduce the impact on their sustainable development. This study constructs a strategic plan for responding to public health emergencies in historic districts based on the refinement of the Guidelines for the Design of Urban Green Space for Disaster Prevention and Avoidance and the application of the concept of normal and disaster time conversion. From an academic perspective, the study fills the research gap by tracing the existing inequities and addressing the contradictory issues between conservation and emergency response at a deeper level. From a practical perspective, the proposed strategies help provide guidance and reference for China’s historic districts in future emergency response.

This study consists of six main sections. Section 1 is an introduction, which presents the key questions that need to be addressed in the study. Section 2 is a literature review, which systematically compares the research results related to historic districts, urban regeneration, public health emergencies and their management, and China’s existing system for emergencies. Section 3 is the methodology, describing how existing problems can be solved by refining existing policies and applying the concept of normal and disaster time conversion. Section 4 presents the results, a system of specific strategies for responding to public health emergencies in historic districts. Section 5 presents a discussion based on the results, and Section 6 concludes.

2. Literature Review

2.1. Historic Districts

Historic districts are a dynamic type of urban heritage that has been studied over a long period of time [7]. According to Shi Min [8] and Hu Min’s [9] study on the development of the concept of historic districts, there are some differences in the concepts related to historic districts in different regions at different times. Concepts that have overlapped with historic districts include historic conservation areas, historic places, heritage areas, and so on. In 2008, the Regulations on the Protection of Famous Historical and Cultural Towns and Villages issued by the State Council of China defined historical and cultural blocks as “historic and cultural blocks approved by the people’s governments of provinces, autonomous regions and municipalities directly under the central government”. The historical and cultural blocks are defined as areas that are particularly rich in preserved cultural relics, where historical buildings are concentrated in patches, which can reflect the traditional pattern and historical appearance in a more complete and realistic manner, and which are of a certain scale. This concept is used for the historic districts in this study. Historic districts are special not only for the cultural heritage they possess, but also for the urban pattern they contain [10]. Historic areas are often located in the core of a city and have witnessed the development of the city from ancient times to the present day. At the material level, the historical buildings and spatial texture in historic areas are highly distinctive and have important theoretical research significance; at the spiritual level, historic areas carry the most distinctive local scenes and customs, and residents have a deep emotional attachment to them [11]. Since many historical buildings and much historical information were lost in the past when there was a lack of awareness about the preservation of historical districts, the system related to the preservation of historical districts has increasingly improved.

Since the State Council of China announced the first batch of historic districts in 2015, more than 1200 historic districts and about 57,000 historic buildings have been recognized as of the end of November 2021 [12]. China does not yet have a clear system for classifying historic districts. Depending on when the historic districts were first built, the earlier ones can be traced back to the 13th century (Tang Dynasty), and the later ones to the mid-20th century. The huge time span allows for a wide variation in the style and internal layout of historic districts. Based on the core functions of historic districts, they can be classified as commercial, industrial, and residential [13] (

Table 1. Classification of Chinese historic districts according to core functions.

Type	Features	Example	Main Groups of People
Commercial	Mainly commercial functions, such as shopping, restaurants, and hotels. The appearance of the historic buildings is preserved and the interior functions are replaced commercially. A large number of indigenous people have moved out of the districts, and the historic districts form distinctive shopping areas in the city.	Xintiandi Historic District, Shanghai	Tourists Merchants
Industrial	Transformed from the past industrial land, such as the transformation of old factories.	The First Automobile Manufacturing Plant Historic District, Changchun City, Jilin Province	Tourists
Residential	Most of the original residential functions are retained, and the living scenes in the districts are obvious. Traditional style residences are the main body of the districts. At the same time, certain commercial functions are introduced in the street-facing part. Tourist visitors and neighborhood residents coexist.	Zhongshan Middle Road Historic District, Hangzhou City, Zhejiang Province Jishan (Shu Sheng’s hometown) Historic District, Shaoxing City, Zhejiang Province Sanfang Qixiang Historic District, Fuzhou City, Fujian Province	Residents (Indigenous People, Tenants) Tourists Merchants

). Among the three types, the commercial and industrial types account for a relatively small number, while the residential type has the largest number. At the same time, residential-type historic districts are also the most prominent and noteworthy among the three types in terms of people-related issues.

Due to the rapid development of new urban areas, historic districts were gradually transformed from prosperous centers of the past into backward quarters in the city. In the process of urban development, historic districts have gradually experienced a decline in neighborhood vitality and various social problems along with it [14]. Historic districts have become weak parts of the city, playing the role of urban villages. Due to their old age, most of the roads in historic districts only meet the needs of pedestrians, and the scale of roads is small. The building density in historic districts is high and the spacing is small; for example, the building density of Langzhong, an ancient town in Sichuan, exceeds 60% [15]. The aging of infrastructure in historic districts is a serious problem, and there is a lack of sanitation facilities, even household toilets. In addition, historic districts usually have complex populations, complicated property rights structures, and unclear ownership. In Shaoxing City, Zhejiang Province, for example, its historic district contains various types of property rights, such as unit properties, private properties, and rented houses. Even one historical building is divided into several property rights. Such problems make the management of historic districts difficult and must be solved urgently. The regeneration of historic districts has important social, cultural, economic, and aesthetic value. Addressing the real needs of people becomes the focus and challenge of the regeneration of historic districts.

2.2. Urban Regeneration

As the world’s urban population surpasses the rural population, a milestone in the global urbanization process, there is a growing need to renew and optimize the urban environment [16]. One of the main means of solving the population, resource, and land problems caused by urbanization, urban regeneration is an effective way of enhancing land value and improving the environment [17]. According to the evolutionary studies of urban renewal-related concepts by scholars such as Ding Fan [18] and Dong MaLi [19], the term and concept of urban regeneration originated in the Western world and has evolved over nearly a century through urban renewal, urban redevelopment, and urban regeneration. The development of urban regeneration in the West can be grouped into four distinct stages [19] due to the effects of war, industrialization, and economic recession (

Table 2. History of urban regeneration in Western countries.

Stage	Period	Target	Characteristics
1	1960s	Slums	Large-scale demolition and rebuild
2	1970s	Public housing	Community-scale regeneration of a welfare character
3	1980s	Old urban areas	Market-oriented development of old urban areas
4	1990s	Urban declining areas and poorly planned non-declining areas	Integrated social, economic, and cultural regeneration

). In short, urban regeneration refers to the improvement of the physical, social, economic, and ecological aspects of urban areas through a variety of actions including redevelopment, rehabilitation, and heritage preservation to meet the requirements of urban development and satisfy the needs of urban dwellers [20]. Overall, it shows a shift from solving material problems such as housing to integrated social, economic, and cultural development. The development of urban regeneration in China, which lags behind that of the West, follows the pace of the West [21].

The development of the concept of sustainability has also led to many studies on the integration of sustainability into urban regeneration [22]. As sustainable development shares economic, social, and environmental aspects with urban regeneration, it was recognized that the two should be integrated, and thus, sustainable urban regeneration strategies should be explored. Since the 1980s, the term “sustainable communities” has emerged in many countries around the world [23]. The U.K. government introduced the Sustainable Community Plan in 2003, which demonstrated that sustainable communities could meet the diverse needs of existing and future residents; that they were safe and inclusive and well planned, built, and managed; and that they provided equal opportunities and sufficient services for all [24].

Urban regeneration is a key factor in promoting healthy and attractive communities [24]. Urban regeneration is also a wise way to make cities pay more attention to and address the needs of people. The demand for urban regeneration is gradually growing due to urban development, and urban development promotes urban regeneration. Urban regeneration is a higher level of background for the current regeneration of historic districts, which drives the process of regeneration of historic districts. With the help of urban regeneration, more attention is paid to the regeneration of historic districts in modern cities. At the same time, as a special kind of target of regeneration, historic districts are also an important way for cities to discover and preserve their own character. Historic districts generate different needs from other regeneration targets. The special needs in the process of historic district regeneration will also be fed back to urban regeneration and improve the connotation of urban regeneration, which can provide experience and lessons for subsequent regeneration. The results of the regeneration of historic districts then influence the development of the city, such as the positive impact on the economic development and cultural dissemination of the city after the appropriate transformation of the historic district for commercialization. So far, urban development is promoted to some extent, and then becomes the driving force for the next round of urban regeneration. Conversely, if historic districts are not properly regenerated, they can also hinder urban development (Figure 1).

2.3. Public Health Emergencies and their Management

A public health emergency is a sudden outbreak of a major infectious disease, mass unexplained disease, severe food and occupational poisoning, and other events that seriously affect the health of the public [25]. From ancient times to the present, infectious diseases have been a major factor affecting human health and impeding human development. The International Health Regulations, revised in 2005, are currently the only legal framework governing global health security. A public health emergency of international concern (PHEIC) is an extraordinary event which constitutes a public health risk to other states through the international spread of disease and potentially require a coordinated international response. Since 2009, the World Health Organization has declared six public health emergencies of international concern of major impact (

Table 3. Public health emergency of international concern (PHEIC) declared by the WHO.

Time of Outbreak	Event	Time of PHEIC	Time of End	Deaths
2009	Influenza A (H1N1)	April 2009	August 2010	12,469
2013	Poliomyelitis	May 2014	-	-
2013	Western African Ebola Virus Epidemic	August 2014	June 2016	11,325
2015	Zika Virus Epidemic	February 2016	November 2016	-
2018	Democratic Republic of Congo Ebola Epidemic	July 2019	June 2020	2299 (as of 3 July 2020)
2020	COVID-19	January 2020	-	6,345,595 (as of 8 July 2022)

). The COVID-19 pandemic became the most serious global public health emergency ever declared by the WHO. According to WHO, globally, 551,226,298 confirmed cases of COVID-19 had been reported to WHO as of 5:33 PM CET on 8 July 2022, including 6,345,595 deaths [26] (Figure 2). However, the true number of deaths may be higher. According to Pillai [27] Guilmoto’s [28] study, there was under-registration in both the U.K. and India. Massachusetts, USA, may have doubtful data for some groups, such as Blacks and Latinos, due to chronic health inequities [29].

As COVID-19 continues to spread, the emergency management of public health events has once again become one of the topics of academic discussion. Emergency management is the process of effective warning, control, and management of emergencies. In Western countries, the theory of emergency management has mainly emerged as crisis management theory, and research on modern public crisis management began in the 1960s [30]. The United States has a clear internal structure and division of work in disaster prevention and relief organization [31]. In the process of industrialization, urbanization, and modernization, the United States has experienced all kinds of public health events of small and large infectious disease outbreaks, and has become one of the countries with a sound public health system and a solid public health foundation. The U.S. response mechanism for public health emergencies can be divided into three parts [32]: pre-epidemic emergency preparedness, mid-epidemic response, and post-epidemic recovery.

According to the visual analysis of the search results on the CNKI database (Figure 3), the research related to emergency management in China started late, sprouting at the end of the 20th century [33]. After the 9/11 attacks in the U.S., China began to pay more attention to its own emergency management. The occurrence of COVID-19 brought a new peak to the research on emergency management after SARS in 2003 and the Wenchuan earthquake in 2008.

Since the SARS epidemic in 2003, China has attached great importance to the emergency response to public health emergencies and has gradually improved its relevant policies [34]. China did not have an emergency response plan for public health emergencies at the time of the SARS outbreak, after which the Chinese government drafted and issued the Regulations for Public Health Emergencies in half a month’s time. The urgent release of the regulations was highly relevant and realistic in addressing the problems that existed at the time, but there were certainly omissions and shortcomings. In the more than ten years since, China has continued to issue relevant laws, regulations, and normative documents (

Table 4. Important documents issued by China related to public health events.

Issue Year	Document Name	Number of Revisions
1989	Law of the People’s Republic of China on the Prevention and Control of Infectious Diseases	1
1991	Measures for the Implementation of the Law of the People’s Republic of China on the Prevention and Control of Infectious Diseases	0
2003	Regulations for Public Health Emergencies	1
2006	National Emergency Response Plan for Public Emergencies	0
2006	National Emergency Response Plan for Public Health Emergencies	0
2006	Guidelines for the Preparation of Community (Township) Emergency Plans for Public Health Emergencies	0
2007	Emergency Response Law of the People’s Republic of China	0
2007	National Health Sector Health Emergency Management Work Standards	0
2011	Multi-sectoral Emergency Coordination Mechanism for Public Health Emergencies	0
2015	National Health Emergency Work Standards for Disease Prevention and Control Institutions	0

). China’s provinces and cities have also been preparing their own documents based on those issued by the national government. China has continued to improve on the omissions that exist in the field of public health, but the speed of revision of relevant documents is far less than that of some Western countries. For example, the Regulations for Public Health Emergencies were released in 2003 and have only been revised once in 2011. In contrast, the Law on Sanitary Epidemic Prevention of Citizens of the Russian Federation has been amended 41 times in the 20 years from its release in 1999 to 2019 [35]. Thus, China’s legal regulations for responding to public health events lag behind the real needs, making it difficult to adapt to increasingly volatile emergencies [36].

2.4. China’s Existing System for Emergencies

China’s initial understanding of emergency sheltering only emerged after the 1976 Tangshan earthquake. Emergency service facilities are important public facilities for cities to resist disasters and ensure safety, and are an important spatial guarantee to enhance the resilience of cities [37]. Shelters are divided into emergency shelters and stationary shelters according to the function of the shelters. Emergency shelters are small, open areas or public facilities near buildings, such as small gardens and small squares, with simple functions; stationary shelters are generally parks, squares, and car parks with larger areas, which can provide a place for disaster victims to seek refuge and rescue for a long time [38]. Urban emergency shelters are of great significance for disaster prevention and mitigation [39].

Currently, there are three levels of disaster prevention parks in China that function as shelters in the event of a disaster: central disaster prevention parks, stationary disaster prevention parks, and emergency disaster prevention parks (Figure 4). Disaster prevention parks are urban parks and buffer zones built to protect the lives and property of citizens and to strengthen the disaster prevention structure of cities such as large urban areas in the event of a disaster [40]. The central disaster prevention park has a large capacity and can be used as an emergency command center, medical rescue center, rest center for disaster relief teams, and other facilities with a service radius of up to 3 km. The stationary disaster prevention parks complement the central disaster prevention park and are designed to accommodate people who are temporarily unable to evacuate in the central disaster prevention park, with a service radius of 500 meters and within a 10-minute walk. The emergency disaster prevention parks are evacuation areas accessible within three minutes of the affected person and are mainly street parks. Japan was the first country to define and propose the construction of disaster prevention parks and urban disaster prevention parks, such as Miki Disaster Prevention Park in Hyogo Prefecture, Kuboji Green Space in Osaka Prefecture, Oshu Disaster Prevention Park in Ichikawa City, and Inaga Park in Nagoya [41]. The 27 parks in Kobe City became the second largest evacuation space after schools during the 1995 Hanshin-Awaji Earthquake in Japan [42].

Due to the limitations of internal space and street layouts, public spaces in historic districts cannot reach the scale of disaster prevention parks. The shelters in historic districts are more often small squares in streets and alleys. In response to COVID-19, these small sites are more disorganized and spontaneous in their function.

2.5. Research Gap

2.5.1. Lack of Solutions to the Inequity between Historic Districts and Modern Residential Areas in Cities in the Event of a Public Health Emergency

The problem of inequity between historic districts and modern residential areas in the event of a public health emergency is due to a combination of factors (Figure 5), with two main dimensions: (1) poor and inadequate infrastructure in historic districts, and (2) a lack of a comprehensive emergency response plan in historic districts. This vicious cycle of inequity is referred to as an inequity trap in this study. Facilities such as water supply and drainage, electricity, and communication are all relatively backward in China’s historic districts. In particular, the lack of sanitary facilities and the lack of independent toilets for some households are highly risky for health and safety. Most roads in historic districts are of small scale and simple form, strongly affecting the arrival of evacuation and rescue vehicles. In addition, the high building density and small building spacing in the historic districts make them lack the conditions for the placement of general infrastructure for disaster. Compared to other urban areas, historic districts lack normative arrangements for responding to public health emergencies. Most urban residential areas meet modern emergency standards, with well-planned emergency access and infrastructure, and clear management personnel. Residents of historic districts face higher health risks and infrastructure issues. As a result of COVID-19, the existence of the inequity trap was brought to light. However, there is a lack of research and solutions to this problem.

Lack of Research on Infrastructure for Disaster in Historic Districts

Based on the search results of the CNKI database, there are few research articles on infrastructure for disaster in China, and there are no research articles on infrastructure for disaster in historical districts (

Table 5. Search results of subject terms in CNKI (search time: 18 October 2022).

	Subject Terms	Number of Papers
(1)	(Infrastructure)	323,848
(2)	(Infrastructure for Disaster)	202
(3)	(Infrastructure for Disaster) AND (Historical Districts)	0

). The visual analysis of Table 5 (2) using CiteSpace (Figure 6) shows that the research on infrastructure for disaster in China is mainly focused on responding to natural disasters such as floods and earthquakes, and lacks studies on responding to health events. This leaves no measurable facilities for responding to public health emergencies that can be applied to historical districts at this stage.

Lack of a General Plan for Responding to Public Health Emergencies in Historic Districts

The previous review of China’s policies and regulations for responding to health events shows the lack of experience in responding, as well as the lack of detail in relevant policy documents. Historic districts can be considered as large complexes of buildings due to their specificity in the city in terms of pattern and character. In fact, historic districts are often relatively independent communities within cities. However, most of the current emergency regulations in China are detailed on a provincial and municipal level, and there is no emergency strategy specifically for the special object of historic districts.

2.5.2. Lack of Research on the Balance between Usual Conservation and Disaster Response in Historic Districts

Historic districts show a clear conflict between usual conservation and disaster response, and the balance between the two is broken in case of public health emergencies (Figure 7). Historic districts in China represent the pure historical and cultural connotation of the area, with a rich collection of historical buildings and customs. Precisely because of the value of historic districts, the regeneration of historic districts can only be executed in an incremental way that does not destroy the overall pattern. However, cultural preservation of historic districts also limits the direct placement of modern disaster preparedness spaces and equipment. The spaces in historic districts that met the needs of residents centuries ago are no longer appropriate for modern needs. When it comes to emergencies, the high building density, small road scale, and weak infrastructure of historic districts are objective conditions that limit evacuation and disaster relief. Most new urban residential areas meet modern standards for emergency response. On the other hand, the necessary means used in response to public health emergencies may have a negative impact on the protection of the ecological environment of the historic district, such as the spraying of disinfectants causing excessive chemical levels in water bodies and harm to flora and fauna; and the generation of medical waste causing environmental pollution.

3. Methodology

3.1. Tracking and Refining Existing Policy

The Guidelines for the Design of Urban Green Space for Disaster Prevention and Avoidance is a specification requirement for disaster prevention green space published by the Ministry of Housing and Urban-Rural Development of China in January 2018 [12]. They offer a suitable guide for the construction of disaster prevention spaces and provide comprehensive requirements in many aspects such as site selection, facilities, traffic flow, planting, etc. The guidelines divide disaster prevention green space into three levels of different scales: emergency green space for long-term, emergency green space for short–medium-term, and emergency sheltered green spaces (

Table 6. Disaster prevention green space classification required by the Guidelines for the Design of Urban Green Space for Disaster Prevention and Avoidance.

Classification		Cover Area (Unit: m2)
Long-term		500,000
Short–medium-term	Short-term	200,000
	Medium-term	10,000
Emergency sheltered		2000

). The guidelines cover regional-scale planning for disaster prevention green space with a large site area and service radius, and thus are not appropriate for application in historic districts.

Therefore, based on the construction requirements of the above-mentioned document for the third level of disaster prevention green space—“emergency shelter green space”—this study proposes strategies for the construction of smaller levels of “micro disaster relief space” in five areas: (1) emergency preparedness programs at the planning level, (2) installation of modulized variable devices, (3) environmentally friendly health protection, (4) disaster prevention preparation at the spatial level, and (5) plant configuration. Then, according to the aspects mentioned in the original law that need to be considered for disaster prevention, the five strategies are refined (

Table 7. Selection of strategies based on the requirements for the construction of emergency sheltered green spaces in the Guidelines for the Design of Urban Green Space for Disaster Prevention and Avoidance.

Requirements for the Construction of Emergency Sheltered Green Spaces	Description	Strategies in this Study	Strategy Refinement
Water supply facilities	All pipelines are connected with municipal pipelines	Emergency preparedness programs at the planning level	Development of a comprehensive contingency plan Improving the public service system
Power supply facilities
Communication facilities
Firefighting facilities	Distance between fire extinguishers shall not exceed 120 m		Refinement of the disaster prevention system
		Installation of modulized variable devices	Disaster prevention facilities integration with recreational facilities
			Prefabricated assembly
Emergency toilet	Combined with urban green space
Recreation	Entertainment function		Disaster prevention facilities combined with paved seating
Popularization of science	Popularize knowledge of disaster prevention		Conservation of the ecosystem, flora, and fauna
Ecology	Eco-friendly	Environmentally friendly health protection
Garbage storage and transportation facilities	Combined with urban green space		Post-disaster waste transfer streamline
Emergency access	Emergency passage shall be unblocked	Disaster prevention preparation at the spatial level	Contaminant isolation
Emergency signs	Set up indication signs and evacuation route map at eye-catching positions		Special accommodation for casualties Special population needs
Distribution site	Use open space to set up a site for disaster prevention goods
		Plant configuration	Establish some structural plants
Landscape aesthetics	-
			Establish some medicinal plants

). These strategies address the characteristics of historic districts and can provide guidance on how to respond to public health emergencies in historic districts, addressing the lack of detailed response plans for public health emergencies. At the same time, the strategies propose conceptual models that can be a reference to improve the infrastructure for disaster in the regeneration process of historic districts. In this way, the problem of the inequity trap can be solved to a certain extent, and the sustainable development of the historic district can be promoted.

3.2. The Concept of Normal and Disaster Time Conversion and Its Application

The concept of normal and disaster time conversion refers to the combination of usual living spaces and facilities with periods of disaster, meaning that they can be used for leisure and recreation in normal times but can be converted into shelter and rescue centers in an efficient and orderly manner in times of sudden disaster, increasing the flexibility of post-disaster rescue, the effectiveness of resource utilization, and the safety of city residents. This concept is now often applied in the construction of large urban disaster prevention parks.

In the current context, it is difficult for historic districts to enjoy modern disaster prevention facilities due to the narrow historical spatial patterns. In addition, it is not possible to effectively and quickly go to a disaster prevention park to seek shelter in the event of a disaster. The Chinese government and scholars need to pay adequate attention to disaster prevention in historic districts, reduce the inequity of explicit and implicit health facilities brought about by the imbalance of disaster prevention facilities, and optimize the allocation of disaster prevention resources. The concept of normal and disaster time conversion is an entry point to innovatively improve the disaster prevention capacity of historic districts. The flexibility, transformability, reversibility, and adaptability of the concept of normal and disaster time conversion can effectively solve the disaster prevention problems that exist in historic districts.

The creation of micro-shelter systems in historic districts is an important expression of the concept of normal and disaster time conversion. Through the use of existing public spaces and through integration with existing amenities, a highly flexible and achievable emergency response strategy is adopted on a smaller scale in order to achieve the most economical and effective renewal of the disaster prevention system. Ultimately, a comprehensive and scientific disaster prevention system for historic districts will be con-structed to enhance the potential of historic districts to respond to public health events, resulting in the refinement of public health disaster prevention policies for sustainable development based on the concept of normal and disaster time conversion.

4. Results

Based on the refinement of the document “Guidelines for the Design of Urban Green Space for Disaster Prevention and Avoidance” in Table 7, five specific strategies for the application of the concept of normal and disaster time conversion in historic districts were proposed, in order to build smaller levels of “micro disaster relief spaces” in responding to public health emergencies. This will allow for a more systematic, long-lasting, sustainable system of disaster prevention in China’s historic districts (Figure 8).

4.1. Emergency Preparedness Programs at the Planning Level

4.1.1. Development of a Comprehensive Contingency Plan

Cities need to develop a comprehensive contingency plan that not only addresses all hazards currently threatening urban areas, but also anticipates new threats [43]. In urban planning, decision makers need to build an optimal emergency disaster prevention network from the macro perspective of urban land use distribution to reduce the vulnerability of cities in the face of disasters. Taking disasters as an influential factor that cannot be ignored in the future development of cities and as a pre-disaster prevention method will have a positive impact on post-disaster emergency response and recovery.

4.1.2. Refinement of the Disaster Prevention System

At present, the lowest level of urban disaster parks in the city have too large a radius. These disaster prevention parks do not allow residents to have a buffer zone in the first hours of a disaster and do not allow residents to have a temporary shelter for disaster prevention in the initial stages of a disaster. This phenomenon reduces the chances of subsequent rescue and transfer for disaster prevention. Historic districts are more difficult to reach quickly from the existing urban emergency disaster prevention parks due to their historical pattern.

Therefore, it is imperative that the disaster prevention system is refined. While the small, temporary spaces may not be able to sustain the tasks and functions of a large number of people over a long period of time, they can act as a buffer zone when a disaster strikes, acting as capillaries of the disaster prevention system and penetrating deeply into the interior of a high-density historic district. In the event of a disaster, people will be able to reach temporary shelter more quickly.

4.1.3. Improving the Public Service System

From SARS in 2003 to COVID-19 in 2019, large-scale public health events have become one of the important threats to urban public safety and residents’ health [44]. With globalization and the increasingly developed public transport, the flow of people between countries and regions is also increasingly frequent, which means that the virus may spread more widely in a short time. Unlike other natural disasters, high-risk public health events have a more obvious global dimension, testing the response capacity of the urban public service system [45]. Therefore, historical districts should improve the public service system from the perspective of planning, implement and refine it, and ensure that public service facilities and public service personnel complement each other, so that they can respond to disasters flexibly [46].

4.2. Disaster Prevention Preparation at the Spatial Level

The process of regeneration of the historic district should focus on the grading and flow planning of the original spaces, using the original small parks or small public spaces with plants and paths for spatial division. Figure 9 shows the various possibilities of re-dividing emergency space by restructuring the facilities and components of original landscape structures, realizing functional zoning by recombining and moving in the face of unexpected events with its red fixed wall and four blue removable landscape partitions. This can meet the needs of people for streamlined and functional space in different situations, and divide two different levels of traffic lines, as well as the blue isolation area, the green storage area, and the brown living area. In terms of materials, cloth, folding nets, or prefabricated assembly panels could be used as removable landscape partitions to divide the space.

4.2.1. Special Accommodation for Casualties

In the event of a sudden disaster, casualties are inevitable. Firstly, injured people need a space where they can be attended to in a timely manner. Secondly, the majority of people who are still healthy and safe, but psychologically shaken by the disaster, need a separate space isolated from those who have died, to avoid psychological fluctuations, fears, and breakdowns that could lead to riots and make the follow-up of the disaster difficult.

Thirdly, for hygiene reasons, to prevent epidemic problems caused by the rapid decomposition of bodies due to the weather, and perhaps the unusual smells that affect the injured and the living, those who have died need to be isolated in a separate space, which needs to ensure that the smells and sounds are at the end of the flow and minimize disturbance to the rest of the population. This is a lesson we have learned from events that have already happened; for example, in Wuhan, China, in early 2020, at the beginning of the COVID-19 outbreak, the mortality rate was high and there was a severe shortage of medical equipment, hospital beds, and staff. Some people were unable to get hospital beds and died at home, their bodies could not be transferred evenly, and their families had to live with the bodies. At the same time, because of the shortage of staff, there are too many bodies to be disposed of and cremated in a timely manner [47]. From March to June 2022, the outbreak of COVID-19 in Shanghai was accompanied by a hot and humid summer that left much of the vegetables and food that should have been used for relief purposes to rot and pile up outside the community. Due to a shortage of service staff, there were not enough people to handle the rotting vegetables and fruits, and the rot leaked outside during the hot weather, causing a potential health hazard.

In China, the interior streets of historic districts are narrow and difficult to reach by vehicle. In the event of an accumulation of bodies or contaminants, it is more difficult to maintain smooth traffic routes and clean air circulation, increasing the potential for cross-contamination. In a fatal public health emergency (even a short-term one), it is difficult for vehicles to quickly transfer the dead and other contaminants in a timely manner. Therefore, in such a densely populated area, after a public health emergency, it is necessary to set up separate isolation spaces to carry the dead and other contaminants before the arrival of vehicles for rescue transfers, in order to ensure the health of other residents [48]. The occurrence of public health events is mostly unpredictable—the only thing the government and the public can do is accumulate the bitter experience of the past, prepare as comprehensively as possible, and maximize space utilization and conversion rates for sudden outbreaks of all types of health events.

4.2.2. Special Population Needs

In the event of a sudden disaster, there are special groups of people who need caretaker emergency help, such as pregnant women [49], young children, the elderly [50], and other patients with basic illnesses. These special groups of people need backup space to prevent secondary injuries and avoid the threat to their lives from everyday and long-term illnesses in addition to disasters.

In addition to the normal needs in times of disasters, special populations have different potential needs (

Table 8. General needs and potential needs of special populations.

General Needs	Special Populations	Potential Needs
		Materials	Medicines	Special Functional Spaces
Food, supplies, regular medicine, shelter	Elderly people, pregnant women, infants, children, disabled, patients, etc.	Wheelchairs, crutches, oxygen bottles, first-aid equipment (defibrillators, ECG machines, ventilators, etc.)	Chronic disease medicine, emergency medicine, emergency medicine, infant and child medicine	First-aid space, space for birth

). Therefore, in the backup space for special populations, their needs should be met as comprehensively as possible. This special area should be permanently stocked and equipped with emergency medication for common geriatric and early childhood illnesses, cardiac erectors, defibrillators, etc., to give these vulnerable people a chance to survive in case of emergency, even if manpower cannot be deployed.

4.2.3. Contaminant Isolation

It is important to ensure that when dealing with the sick and wounded, the medical waste generated has a fixed area to be housed, preventing epidemics caused by hygiene problems that often occur after large disasters. Secondly, it is important to ensure that the domestic waste of healthy residents in emergency shelter areas is effectively disposed of.

4.2.4. Setting up of Material Storage Areas

It is important to achieve spatially graded quantities of material stocks. In each public emergency, space should be set up a material reserve area, and at the same time, within each block, 1–2 large-scale material reserve areas should be set up according to the scale. Small material reserve areas are flexibly distributed with the public space to ensure the permeability of relief (Figure 10). When disaster strikes, these small material reserves can sustain the affected people until the arrival of large reserves, gradually increasing the disaster resistance and resistance time of the space and buying time for rescue.

It is essential to ensure that reserve materials are checked and updated effectively in everyday life. Specialized functionaries need to be specified to carry out regular checks on the safety and currency of reserve materials, and to renew, replace, and replenish them in a timely manner [51].

In terms of the selection of stockpile materials, durability and containment should be prioritized to ensure the accuracy of medication and food items to achieve maximum relief. It is also necessary to ensure that water purification devices are available to prepare for the collection and purification of natural rivers or rainwater in case of water shortage during disasters. At the same time, firefighting rivers should be guaranteed to be unobstructed in order to ensure the adequate supply of water in case of fire. In addition, the sturdiness and integrity of tools should be guaranteed, such as flood control sandbags, jacks, and shovels.

4.3. Installation of Modulized Variable Devices

4.3.1. Integration with Recreational Facilities

Some of the public spaces in the historic districts are equipped with fitness equipment and slides for children to play with, in order to meet the daily fitness and recreational activities of the residents and children. These devices are made of prefabricated elements, mostly made of steel and plastic, in the form of plates and tubes. The basic shapes and materials of the equipment and installations can be disassembled and assembled in a variety of ways, which offers the possibility of reassembly. In the event of a disaster, the play equipment can be disassembled to vacate the site or to become variable devices; for example, a device can be unscrewed and twisted and folded to become an emergency bed or a frame part of a small isolation space.

In addition, functionally transformed modal constructions are well suited for small sites in historic districts (Figure 11). This kind of construction has the advantage of being flexible, variable, and occupying a small area. The style and appearance of the construction can be specially designed according to the characteristics of the site. The construction consists of a frame structure and detachable plates (Figure 11a). The plates are classified into three forms, two of which can be transformed (Figure 11c). Type 1 and type 2 plates can be transformed into tables, chairs, shelves, and other facilities. The plates and frame structures can be combined in various ways (Figure 11d) by means of small stoppers on the plates and groove splicing in the frame (Figure 11b). Up to six plates can be stored on one side of the construction. In normal times, the construction can be used as a facility for recreation, such as a reading area, lounge, chat area, etc. In case of emergency, the plates can be detached and partitioned for space as removable landscape elements. They can also be transformed into emergency medical spaces such as nucleic acid testing sites, small isolation sites, or material distribution sites. They can be built in different geometries and volumes, without the need for professional operation [52].

4.3.2. Combined with Paved Seating

In parks in historic districts, wooden paving and wooden seating in gardens should be designed and constructed with the ease of disassembly and assembly in mind. This will ensure that the panels can be quickly uncovered or dismantled so that they can be used as emergency supplies. At the same time, the paving should be laid in modal units to facilitate secondary assembly for use as emergency workbenches and panel walls for emergency separation spaces (Figure 11c).

4.3.3. Prefabricated Assembly

In the renewal process, all facilities in public spaces should be composed of prefabricated assemblies in a modular manner as much as possible. At the poles, connection slots or lap holes should be pre-determined in a modular manner to ensure that panels removed from paving and seating can be quickly erected as workstations or partition walls in case of emergency [53] (Figure 12).

Severe earthquakes often result in the breakdown of the water supply and drainage system, making it impossible to use the flush toilets normally used, so it is important to design modular portable toilets that can be assembled quickly in advance to ensure that basic living standards and infrastructure can be established quickly in the event of a space split [54,55]. These modular toilets can be of various types, such as the part-time usual toilet type and the temporary set-up type, with the appropriate type chosen according to the specific circumstances of the park. In terms of the disposal of urine and feces, if the sewerage system has a drainage function, the urine and feces can be discharged directly into the sewerage system. During the Kobe earthquake in Japan, the water flushing toilets in Kobe City could not be used due to the interruption of the water supply. Although temporary toilets were built, the shortcomings such as insufficient number, deteriorating sanitary conditions, and difficult access for the disabled were serious.

4.4. Plant Configuration

4.4.1. Plant Some Structural Plants

In the event of a disaster, the first spatial transformations or the construction of isolated areas are often faced with a shortage of materials and a lack of structural support structures and divisional constructions. Therefore, in the daily decoration of public spaces in historic districts, more structural plants can be planted, such as bamboo, flowering trees, and fruiting trees with straighter branches, and equipped with small cutting tools so that they can be temporarily cut down and used to build and support, or even to make medical materials such as stretchers [56,57,58]. Simple construction methods are chosen according to the characteristics of different plants. Plants with flexibility, such as bamboo, can be bent and tied to create simple spaces. For more supportive plants, they can be used as structural supports and combined with fabric with an enclosing function, and together can quickly build simple isolated spaces (Figure 13).

4.4.2. Planting of Some Medicinal Plants

During the regeneration of historic districts, small areas of medicinal material should be consciously planted, such as plants for hemostasis, anti-inflammatory, and analgesic purposes, in order to prevent the problem of insufficient medicinal materials in the event of a sudden disaster where roads are blocked (Figure 14). At the same time, information on the emergency medicinal use of natural plants should be placed on information boards in residential areas to improve residents’ ability to save themselves in the event of a sudden disaster [59].

4.5. Environmentally Friendly Health Protection

4.5.1. Post-Disaster Waste Transfer Streamline

At the time of the major outbreak of COVID-19 in Wuhan and Shanghai, domestic waste and medical waste were not treated in time. The existing literature research shows that the COVID-19 outbreak and average daily temperature had a negative coherence [60]. At the time of the outbreak in Shanghai, the temperature had risen, and even the rescue materials were corrupted and could not be effectively handled, which virtually increased the potential health risks.

Because historic districts are characterized by a high density of buildings and people, the probability of these situations occurring is high. If these situations occur and are not dealt with in a timely manner, the sanitary risks posed by debris can easily lead to secondary man-made accidents. Therefore, the accessibility and independence of disaster prevention flows in historic districts should be ensured, and the following measures can be taken:

• In daily life, government monitoring mechanisms and residents’ awareness of disaster prevention should be strengthened, so that piles of debris in disaster prevention routes can be cleared to prevent blockage of the routes.
• During the renewal process, the flow of debris in the historic district should be made up or unblocked to ensure that it leads outside in the quickest way possible, avoiding residential areas. Furthermore, the waste treatment plant can be located at a node with access to traffic.

4.5.2. Conservation of the Ecosystem, Flora, and Fauna

Most historic districts are clustered around water sources and river frontages, which ensure easy access to drinking water for residents. However, in the event of a major disaster, the use of excessive disaster prevention measures in these historic districts on the river can easily threaten and affect the watershed ecosystem.

Chemical disinfectants have a pivotal role in addressing health risks. The COVID-19 outbreak led to the widespread use of chemical disinfectants in the past two years [61]. Practical experience in China has shown that strict disinfection is effective in controlling the spread of COVID-19. Chlorinated disinfectants have been the primary choice in China in response to the COVID-19 outbreak, but there have been concerns about over-disinfection [62]. During the epidemic in Shanghai (March 2022), excess hypochlorite tablets were placed on the pavement, grass, soil, and in sewers. These unscientific and massive doses of hypochlorite disinfectant tablets cause harm to soil, plants, and water sources [63]. This practice has seriously damaged the urban ecology, causing damage to the habitat of many birds, insects, squirrels, and stray cats and dogs, leaving the animals without a safe shelter where they can find clean water and food. At the same time, when the animals’ skin and hair are contaminated with highly concentrated disinfectant solutions, it causes a lot of damage to their bodies. In addition to the damage to plants and animals, residents have reported that the smell of disinfectant in the air is so strong that some people have experienced dizziness and nausea, and the damage to humans caused by over-disinfection and indiscriminate spraying of disinfectant cannot be measured. In addition, there were cases of indiscriminate disinfection by epidemic prevention personnel who visited homes and disinfected pets, furniture, and collectibles owned by the owners, resulting in the death of pets and damage to furniture made of special materials, without any compensation measures or awareness of improvement by the government or those in charge.

In summary, all of these actions are contrary to the concept of sustainability and environmental friendliness, and therefore, eco-friendly disaster response measures should be taken into account in the new renewal process, which can be considered in the following ways (Figure 15).

Firstly, authorities should research and experiment in advance with environmentally friendly and precise disinfectants and drugs to ensure that they do not pose a threat to most mammals (such as stray dogs and cats, squirrels, as well as birds and insects in cities) to protect biodiversity and to ensure that they are not harmful to most plants. More importantly, it must be ensured that the impact of the drugs on water and soil is safe and that toxic drugs do not enter the human body through the circulatory system.

Secondly, precise and careful consideration is needed in the process of disposing of disinfectants and drugs, avoiding large and indiscriminate doses and avoiding throwing them directly into rivers, soil, green belts, and parks. In some seaside cities, decontamination can even affect the marine ecosystem, leading to long-term damage to the ecosystem. Precise disinfection should be carried out at the source of the virus in densely populated areas to minimize and avoid impact, damage, and harm to the environment.

Third, there are policies and mechanisms for emergency feedback. Once damage is found to the ecosystem’s flora and fauna, there should be explicit provisions and public oversight, with multiple powers of restraint, so that enforcers immediately stop mass disposal and clean up or remediate quickly, rather than just enforcing decontamination orders.

5. Discussion

During the urbanization process, historic districts that lack a comprehensive legal framework for protection are more vulnerable to emergencies [64]. Historic areas have higher vulnerability in times of disaster due to limited infrastructure and building density, while modern urban areas with better facilities and emergency services usually have higher disaster response capacity [65]. This study summarizes the inequities in response to public health emergencies between historic districts and modern residential areas during the urbanization process through a review of the literature. The factors of the inequities have been extracted and the interactions between them have been sorted out (Figure 5). Shi [66] and Geng [67] identified emergency shelters as an important component of disaster response and mitigation, but historical districts have paid insufficient attention to shelter construction [68]. Suo Jian [69] and Li Weian et al. [70] made suggestions for the construction of governance mechanisms for public health emergencies, which illustrates the importance and effectiveness of government leadership in governance. Li Xuefeng [71] showed that China’s health emergency management system currently suffers from unspecific legal provisions.

This study innovatively applies the concept of normal and disaster time conversion to the strategy development process and establishes a policy strategy system for public health events in historic districts based on the Guidelines for the Design of Urban Green Space for Disaster Prevention and Avoidance [12], which provide five strategies based on overall planning. The five strategies focus on overall planning, spatial setting, modular installation, planting, and environmental friendliness, and can complement each other to play an important role in disaster preparedness and response. By proposing strategies for disaster preparedness infrastructure, policy, and law in China’s historic districts, and the use of existing amenity spaces for renewal to ensure the sustainability of local culture, the inequities between residents of historic districts and modern urban settlements are addressed while balancing emergency response and historic district preservation.

This study constructs a policy refinement strategy system guided by the concept of normal and disaster time conversion to break through the limitations of traditional research on disaster prevention policy, expand the research perspective and content, and provide a reference for historical districts in China when they are faced with inequitable social health facilities and the inability to balance local culture and disaster prevention response issues. At the same time, there are some limitations to this study. The proposed theoretical strategy system has not yet been applied to Chinese historic districts in practice on a large scale, and the performance of this strategy system should be empirically tested in future research.

The United Nations has proposed disaster risk reduction outlines such as strengthening disaster risk governance, investing in disaster reduction to increase resilience, and strengthening preparedness to respond effectively to disaster risks [72]. However, China is in the early stages of promoting and developing the idea of “disaster-level transformation” and may face some practical and economic problems. For example, perhaps the cost of building infrastructure to meet the flexible transformation will be much higher than the cost of normal construction, and perhaps some of the more robust and modular materials will be more expensive. The design and construction costs that the government would need to pay to professionals could be much higher. In addition, construction processes that break with traditional building habits may extend the construction period. All of these issues may lead investors to question the feasibility of the design and the short-term financial return. Thus, in subsequent research on this topic, it may be possible to explore two aspects in more depth:

(1)

Start with a technical and material perspective. The various historic districts have different characteristics in terms of economic development and culture. Depending on their topography and climate, their specific spatial construction may need to be further studied and refined for the individual under the framework of the strategies proposed in this research. The specific structural transformation process can perhaps be combined with material and regional characteristics to suggest more possibilities.

(2)

From the perspective of economic and engineering management, the issue of responsibility and economic agents in the construction process can be explored: for example, the government, as a public investor, can provide some comprehensive and reasonable incentives to make the construction habit of normal and disaster time conversion popular in order to obtain long-term benefits, improve the safety of historic districts, and establish long-term disaster prevention planning.

6. Conclusions

Historic districts in cities are important spaces that carry local history and culture. The public health emergencies in recent years have caused great resistance to the development of historic districts and threatened people’s health and well-being.

Researchers and city governments have proposed a range of disaster prevention policies and measures for modern urban areas. However, the relevant disaster prevention policies for historic districts are not sufficiently detailed. Recent health emergencies have challenged the responsiveness of urban emergency systems and public services in historic districts, which lack adequate infrastructure for disaster preparedness and have weak community management. The high density of buildings makes it difficult to establish emergency spaces and emergency facilities in historic districts in accordance with existing disaster prevention policies, making it difficult to ensure the lives and health of residents in these areas in disaster.

The concept of normal and disaster time conversion offers a new solution to the problem of public health disasters in historic districts. This study constructs and proposes a theoretical strategy system for the refinement of disaster prevention policies based on the concept of normal and disaster time conversion. The five strategies proposed in this study range from large to small, from macro-urban planning to meso-spatial design to micro-simulation equipment, integrating planting configurations and health protection, creating a multi-level system of cooperation between different disciplines and duty bearers. This system of disaster preparedness enhances the capacity of historic districts to respond to public health events in two ways: by improving pre-disaster prevention mechanisms and by strengthening responses during disasters.

The system developed is characterized by a meticulous strategy established before the disaster, setting up an emergency transformation model, making full use of the existing spaces and facilities in the historic district, respecting the local site, and making full use of the flows and spaces that already exist in the local space for disaster prevention and response, in order to ensure the healthy, equitable, and sustainable development of the historic district and to meet the emergency shelter and survival needs in constrained areas. It is essential to ensure that historic districts can prepare adequately for disasters before they occur, respond quickly and effectively in the event of a disaster, and provide a basis for sustainable post-disaster development.

This study constructs a policy refinement strategy system guided by the concept of normal and disaster time conversion to break through the limitations of traditional research on disaster prevention policy, expand the research perspective and content, and provide a reference for historical districts in China when they are faced with inequitable social health facilities and the inability to balance local culture and disaster prevention response issues. The study also has some limitations. The proposed theoretical strategy system has not yet been applied to Chinese historic districts in practice on a large scale, and the performance of this strategy system should be empirically tested in future research.