**4. Methodology**

Researching real-world challenges in the context of sustainability studies requires a co-produced knowledge process, allowing for various stakeholders from both the scientific world and the non-scientific world to be part of the research setup. In the context of air pollution in Metro Manila, previously mentioned studies found that PUJs are amongs<sup>t</sup> the main polluters in the transport sector. Regarding the input into decision-making processes that impact the transport sector, participation from practitioners, such as jeepney drivers, is needed for the process of achieving sustainable solutions. Based on our literature review, the state of the art for setting up sustainability research projects is the TRANSFORM approach that we combined with the concept of "follow the innovation" (FTI). While TRANSFORM was already depicted earlier, the FTI approach allows for "joint experimentation and learning by [ ... ] fostering participatory processes of testing, jointly with local stakeholders, institutional and technical innovations and adapting them to the local" [36]. Methodologically we follow the three TRANSFORM and FTI approach requirements. By combing both methodologies, we apply the following transparent, structured, and replicable sequences of three steps:


Working on air quality managemen<sup>t</sup> in Metro Manila, the research setup described here is an innovative package of technological, socio-political, and health interventions for decision-makers to mitigate BC emissions. In detail, this is put together by a first pillar, which assesses BC pollution levels and adaptation strategies in the transport sector. The second pillar aims at understanding the institutional environment of air quality regulations, including the local and national governance structures in the Philippines. The third pillar reflects on the assessment and current state of the problem of human exposure to BC and related potential health e ffects. Finally, the fourth pillar analyzes the institutional workings of the air-pollution-related innovation system to e ffectively integrate the knowledge obtained from the findings into sustainable solutions (Figure 2). The complexity of the pollution problem "requires the constructive input from various communities of knowledge" [37], which involves a scientific inquiry approach that cuts across disciplines, synthesizes theory and methodology, and co-creates solutions. Expectations concerning the exchange of knowledge between science and policy, including knowledge coproduction [38] and local embedment, were assured by the research approach [26,27,39].

**Figure 2.** Setup of a transdisciplinary approach to mitigate emissions of black carbon (BC) in Metro Manila.

The goal of this paper then was to provide an overview of a novel transdisciplinary research framework in the context of emissions reduction that was initiated in 2019 while the implementation is ongoing. While the overall research design is a collaborative process, knowledge is also generated at a disciplinary level to then be integrated toward inclusive solution processes. The three disciplinary pillars are framed by the fourth pillar on innovation and transformation pathways, ensuring local embedment and the creation of shared knowledge. All pillars together lead to the overall aim (arrow) toward BC emission mitigation (see Figure 2).

### *4.1. Measurement Campaign: Instrumentation for Tracing Black Carbon*

This component of the sustainability research setup aims at cooperation with local partners for optimal air quality measurement campaigns with innovative technologies. The optimal technology selection for a measurement campaign should be made based on previous research [13,32] and keeping in mind the sustainability goals. If no previous research exists, it is suggested the technology selection adopts well-known world standards. When working in the Global South, it is important to apply state-of-the-art instrumentation that can be developed remotely and does not necessarily need to be produced at the measurement location, since economically less developed regions cannot afford the state of the art and there could be an issue of available expertise to do high-quality research.

In the framework of the TAME-BC campaign in 2019–2020, a measurement container was employed to determine the particulate air pollution in the Manila North Port and East Avenue (Figure 1). To ensure the gathering of high-quality measurement data, aerosol instrumentation was handled according to recommendations provided by the World Calibration Centre for Aerosol Physics (WCCAP) in the frame of the World Meteorological Organization's (WMO) Global Atmosphere Watch (GAW) Programme. The sampling was done following the recommendations described by the GAW report 227 [40] to minimize the particle losses due to diffusion, impaction, and settling. Furthermore, the relative humidity was kept below 40% for the measurement, employing a Nafion®Permapure dryer [41] and by keeping the temperature in the air-conditioned measurement container at 27 ◦C.

The aerosol instrumentation used in TAME-BC measurement campaign includes mobility and aerodynamic particle size spectrometers (MPSS—TROPOS-type and APSS—model 3221, TSI Inc., USA, respectively), absorption photometers, such as the aethalometer and the multiple angle absorption photometer (MAAP, model 5012, Thermo Inc., Waltham, MA, USA), a volatility-tandem differential mobility analyzer (V-TDMA, TROPOS-type), an aerosol chemical speciation monitor (ACSM, Aerodyne Research Inc., Billercia, MA, USA) to measure the aerosol particle size distribution, absorption coefficient, volatility properties, and online chemical composition of aerosol particles, respectively, and an automated weather station. Aside from the custom-made state-of-the-art measurement container, which stayed in a single location for a set time, a complimentary state-of-the-art portable aerosol backpack was developed to investigate BC exposure concentrations along the streets and in different locations that require mobility. The instrumentation inside the backpack includes an optical particle size spectrometer (OPSS, model 3330, TSI Inc., Minnesota, MN, USA) and a micro aethalometer (microAeth® AE51, MA200; AethLabs, San Francisco, CA, USA). Measurement data, such as the particle size distribution, BC mass concentration, and geospatial position, are handled by a single board computer.

Within a transdisciplinary approach, technological solutions need to be planned and applied in cooperation with local partners. Therefore, the whole measurement campaign technology selection process was a collaboration with local experts.

### Theory to Measurement Practice: Appropriate Embedment in Metro Manila

The first research pillar was dedicated to the assessment of pollution levels. Considering the local conditions, it was necessary to use tailor-made instrumentation in Metro Manila that nevertheless followed world standards for high-quality data collection. The exact composition of the measurement technologies was chosen based on experiences from previous measurement campaigns in Metro Manila.

Planned measurements and investigations took place in Manila North Port and East Avenue roadsides in Quezon City (Figure 1). Air pollution sampling in East Avenue allowed for investigating the pollution at the source point. The measurements done during TAME-BC are expected to provide an accurate source apportionment and information on how the particulate air quality is influenced by different sources in Metro Manila [42]. Such systematic pollution characterization gives the necessary additional insight into the health risks of exposed populations.

The establishment of long-term air-pollution-monitoring sites is vital for tracking the changes in BC concentrations. Long-term monitoring ensures tracing solution-orientated project goals back to the current state of the problem. Assessment and tracking project realization was the aim of the air quality measurement practice within this project. The long-term air-pollution-monitoring site was suggested to be located at the Manila Observatory (MO), where MACE2015 previously stationed aerosol instrumentation as a representative of urban background pollution level. Such a continuous scientific monitoring component is important because it can provide high-quality and long-term data to validate the effectiveness of technological, socio-political, and health innovations and transformations in reducing the emissions of BC in the course of this project and beyond.

The measurement and investigation stages executed in Metro Manila, Philippines, relied on the literature review and on the methods that were proven to provide comprehensive information on the pollution properties in TROPOS's previous studies in Metro Manila involving container measurements (e.g., estimating the emission factors) [16,43] and in mobile measurements studies [33]. Although the air pollution data is not presented in this manuscript, the goal of pillar one is to perform a thorough air quality assessment. The Metro Manila case study example that focused on BC emissions aimed at a scientific collaboration with the local science institutes by doing container measurements as part of pillar one. Measurements through the TROPOS Aerosol container were performed in the port from 19 December 2019 to 25 January 2020. Measurements in East Avenue right outside the Quezon City Hall ran from 30 January 2020 to the end of 25 February 2020. Compared to the port, higher BC concentrations were observed in East Avenue, which was heavily influenced by local heavy vehicle traffic emissions. Such a setup involving placing a measurement container in two various places provides the local transport planning authorities and policymakers with quality data for better decision-making. Container measurements provide the most accurate data on air pollution (compared to mobile sensors), and for the specific Metro Manila case study, the BC values in 2019 were observed to be higher than what was measured by Alas et al. in 2015 [33] in Taft and Katipunan Avenue.

This component of the setup focuses on applying the TROPOS measurement container and is a valuable scientific addition to the TAME-BC, as it serves as a quality assurance for all measurements made within the project. Policy assessment, coordination, and health awareness pillars draw their conclusions based on the aerosol characterization done in this pillar. Therefore, air pollution measurements should be covered in the first pillar to serve as a starting point for further actions.

### *4.2. Air Quality Management and Policy Implications*

Investigating the institutional settings of past and current states of air pollution challenges by applying a case study approach in Metro Manila represents the second pillar. The problem of air pollution was already assessed and recognized by the governmen<sup>t</sup> of the Philippines in the 1990s. Even though air pollution measurements were not as detailed back then as under the current project, it led to the issuance of the Philippine Clean Air Act in 1999. The Department of Transportation (DoTr) recently initiated the already mentioned PUVMP, mainly aiming to modernize the public transport fleet toward Euro 4-compliant engines for all public utility vehicles, where the obvious targets among those are also the unique jeepneys. Such a decision created division: Some of the a ffected groups oppose the modernization program arguing that it threatens transport cooperatives and single-unit jeepney owners. The government, however, remains committed to the phase-out of vehicles using older engines to ensure safety and decrease pollution, despite strong resistance. Lack of scientific knowledge in implementing environmentally and socially sustainable solutions may result in a failure of the PUVMP, which will a ffect the livelihoods of many people.

To gain a deeper understanding of the institutional environment surrounding air quality managemen<sup>t</sup> in the Philippines, the two-fold approach that is taken must be highlighted. As suggested by the selected TRANSFORM methodology, foresight and back-casting methods adopted to FTI were applied. On the one side, a thorough content analysis of the regulations in place and how they evolved was conducted. On the other side, discrepancies between the de jure and de facto regulations can only be unraveled by understanding how those regulations are embedded in a wider institutional context on the local level. This means that interviews with those a ffected by the regulations are conducted.

Theory to Policymaking Practice: Appropriate Embedment in Metro Manila

While the political and public awareness toward air pollution-related problems in Metro Manila is increasing, this fosters de jure governance responses by state institutions and de facto mechanisms of the public down to the individual behavior level. However, fairly little is known about current managemen<sup>t</sup> mechanisms that deal with increasing emission levels [17].

The second goal of TAME-BC, therefore, was to investigate and systematically map the dynamically evolving local institutional environment. It includes the evaluation of policies, rules, norms, and values that determine the current state of air quality in Metro Manila. This supports examining knowledge flows on air pollution and its mitigation management, based on local case studies.

In assessing the de jure governance responses to the decreasing air quality in the Philippines, a systematic mapping of governmental regulations served as the first step of the investigation toward air-quality-management-related policies. Starting with an analysis of the Clean Air Act from 1999, relevant ensuing regulations were investigated as well. This was done through the investigation of the national governmental authorities' homepages. The main contributions were from the Department of Environment and Natural Resources (DENR) and the DoTr. The most relevant documents were listed and analyzed through a qualitative content analysis using ATLAS.ti (version 8.4.16, Scientific Software Development GmbH, Berlin, Germany). The regulations on the PUVMP were furthermore considered, even though the program was not implemented in the context of air quality managemen<sup>t</sup> in the first place [14]. Nevertheless, as the program aims to replace the old diesel engines with at least Euro 4 standard engines, it was of importance to the overall analysis. Based on the review of air quality managemen<sup>t</sup> regulations, qualitative semi-structured interview guidelines were developed. The interviews were conducted to study the local level response to

policies. Open-ended questions avoided collecting biased pre-formulated answers [44]. Jeepneys are over-proportionately contributing to air pollution. The drivers are over-proportionately exposed to pollutants. Therefore, the target group of the interviews was the jeepney drivers. Various jeepney driver associations serve di fferent routes within Metro Manila. As the jeepney drivers themselves are a very heterogeneous group, they have di fferent perspectives on air pollution, as well as on the modernization program. The di fferent jeepney drivers often position themselves toward the modernization program along the line of opposing the project toward more moderate positions. Within the frame of the TAME-BC project, we interviewed three jeepney driver associations, representing di fferent positions toward the modernization program. One group interviewed rejects the modernization program. A second group interviewed had a moderate stance, while the third group interviewed already participated in the modernization program. This variety allowed for a comprehensive information collection framework. The groups were further selected in regard to the area they worked in. One group interviewed passed the TROPOS container on their route. An additional overlap was created as jeepney drivers were also investigated by the mobile backpack measurement team.

The interviews were conducted with one driver at a time while being on the moving jeepney during usual business hours. A total of approximately 10 interviews per group was conducted (*n* = 30), where an interview lasted for an hour on average. This also allowed for participatory observation during the time on the jeepneys. Additional interviews were conducted with governmen<sup>t</sup> representatives from the DENR, the DoTr, a local governmen<sup>t</sup> unit, and NGOs working in the field of air quality. All interviews, but especially the ones with jeepney drivers, were conducted together with a local research assistant. The research assistant guaranteed ease of the interview situation, mainly by allowing the interview partner to interview in her or his preferred local language. Interviews were recorded and transcribed when permission was granted. The researchers also took notes during the interviews. After each interview, the notes were typed up and discussed among the research team.

Combining interview results with the mobile and stationary measurements can be used for a comprehensive analysis that serves the goals of pillar two. By having identified the exact pollution levels on various routes that were complementary to interviews with the jeepney drivers, the de jure and de facto policy assessment implications of pillar three have a strong basis for producing better local transport sector guidelines.

### *4.3. Awareness Building: Health E*ff*ects Estimation*

The third pillar of TAME-BC was conducted in close cooperation with local hospitals for building health awareness with regard to air pollution problems. The health component of the project aims to increase knowledge of adverse health e ffects caused by ambient air pollution, as suggested in the following paragraph.

The exposure to BC has to be measured ideally for the main polluters and for those who are the most a ffected. Measurements of BC inside jeepneys was conducted by using portable instruments (backpack measurements) used at di fferent locations during di fferent days and times to allow for a more precise picture of the BC exposure levels for the drivers. Ideally, such measurements are done at various times of the day, weeks, and months such that comparisons can be presented. Further, the lifestyle and health conditions of the main polluters and those who are most a ffected should be assessed using the Burden of Obstructive Lung Disease (BOLD) study questionnaire. The BOLD study is an already existing cross-sectional survey that assesses the prevalence and burden of chronic obstructive pulmonary diseases (COPDs) in the Philippines, which developed a validated questionnaire. The lung functions of the main polluters and those who are most a ffected should be examined, ideally using pre- and post-bronchodilator spirometry measurements. Additionally, a cardiovascular assessment should be performed. This includes an electrocardiogram and blood pressure measurements. Lastly, the association between BC and health outcomes can therefore be analyzed using linear or logistic regression models depending on the classes of the outcome variables (e.g., continuous or binary variables). A set of previously selected covariates are recommended to be included to control for their potential confounding effects, such as age, sex, and socioeconomic and lifestyle variables.

### 4.3.1. Theory to Awareness Building Practice: Appropriate Embedment in Metro Manila

Exposure to pollution has several negative associated health effects, as described above. The theory described in the section above was applied in Metro Manila for the goal of BC emissions reduction via awareness building.


We foresee that such data obtained will be vital to health outcome studies. Such studies are being conducted at the LCP to assess the health effects of BC, as BC particulates are known carriers of toxic substances. The data collected in pillar three will also be useful as much-needed evidence to aid policymaking regarding measures to address air pollution, especially now that the public is more conscious of taking care of their respiratory health.
