Impact of Environmental Pollutants on Otorhinolaryngological Emergencies in the COVID-19 Era

Abstract

Air pollution (AP) is a critical environmental factor influencing public health, with well-documented associations with upper respiratory tract (URT) diseases. This study investigates the relationship between ENT emergency department (ENT-ED) visits at Azienda Ospedale Università di Padova (AOPD) and daily concentrations of environmental pollutants during the first year of the COVID-19 pandemic (March 2020–March 2021), compared to pre-pandemic data from 2017. The study focuses on patients diagnosed with URT inflammatory diseases, excluding those with COVID-19 infection, who sought care at the AOPD ENT-ED. Environmental data, including meteorological variables, air pollutants, and major aeroallergen levels, were collected from regional monitoring stations. A total of 4594 patients were admitted in 2020/2021, marking a 37% reduction from 2017, with URT inflammatory admissions decreasing by 52%. A significant decline in PM10, NO₂ and Alternaria levels was observed, whereas Betullaceae and Corylaceae concentrations significantly increased. Multivariate analyses revealed strong associations between aeroallergen exposure and ENT admissions, particularly for Alternaria, which had a notable impact on total admissions (p < 0.001) and was significantly linked to cases of otitis media and tonsillitis. PM10 concentrations on specific days preceding ED visits were associated with increased incidences of pharyngitis and rhinosinusitis (p < 0.05). These findings reinforce the connection between environmental pollutants and ENT emergency visits, highlighting the adverse effects of AP and climate variables on URT diseases, even during a pandemic when enhanced airway protection measures were in place. This study underscores the necessity of stringent air quality regulations and interdisciplinary strategies to mitigate environmental health risks and inform future public health policies.

1. Introduction

The World Health Organization (WHO) officially declared COVID-19 a global pandemic on 11 March 2020 [1]. Governments around the world implemented massive travel restrictions (through the so called “lockdown”—partial or total) to mitigate the spread of this global infection [2]. These decisions brought sudden and immense changes to human activities: not only a reduction in traveling, but also a decrease in access to medical care for reasons unrelated to COVID-19 [3]. Healthcare providers reduced their routine activities, such as surgery or other medical services that were not considered “essential” or urgent, to provide treatment for COVID-19 cases [4]. Furthermore, people reduced their access to health institutions for fear of exposing themselves to the viral infection.

In the General Emergency Departments of the Veneto Region, Italy, an absolute decrease in hospitalizations was described during the lockdown periods, with some of them, such as those due to traumas, accidents at work and road accidents, declining due to lower risk exposure [5]. In other cases, a different perception of urgency in such a dramatic situation often caused patients to avoid seeking medical evaluation even when in need [6,7].

The forced reduction in human activity in cities resulted in a subsequent decrease in air pollution derived from vehicular traffic and industrial activity. In Italy, measurements and comparisons have been conducted on the concentration of environmental pollutants such as particulate matter (PM), carbon monoxide (CO), ozone (O₃) and nitrogen dioxide (NO₂), showing a significant decline in these pollutants during the restrictions [8,9]. Variations in air pollutants (AP), pollen concentration and climatic variations may have an impact on upper respiratory tract (URT) pathology, especially in pollen-allergic patients [10].

The impact of these variables on accesses to the Ear, Nose and Throat (ENT) Emergency Department (ED) admissions in the Azienda Ospedale Università di Padova (AOPD) has already been investigated in the pre-COVID era [11]. The correlation between air quality and human health is receiving increasing attention, yet its connection to ENT urgencies during the COVID-19 pandemic has remained relatively unexplored.

In this study, we aim to describe new data that may contribute to a deeper understanding of environmental impacts on otorhinolaryngological pathologies during the pandemic and provide useful insights for managing future health emergencies.

We examined the impact of the pandemic on ENT ED admissions in the AOPD (I), focusing on variations in the number and typology of admissions during restriction periods. We also conducted an analysis on the changes in environmental pollutants such as PM, chemicals and pollens in the same timeframe (II). Through a comparison with the pre-pandemic period, we aimed to identify trends and substantial changes in the patterns of ENT ED admission in our center (III), as well as to assess the potential role of environmental pollutants in this context (IV).

2. Materials and Methods

This is a retrospective study conducted at the ENT ED of the AOPD, Italy. The data analyzed were provided in reference to two timeframes: from 1 January 2017 to 31 December 2017 and from 9 March 2020 (beginning of Italian lockdown) to March 8th 2021. Both periods therefore cover the duration of one year and refer to two different circumstances: the first timeframe refers to a situation of normality, whereas the second refers to the first year of the COVID-19 pandemic.

The study was conducted in accordance with the ethical standards of the Helsinki Declaration. Data were examined in agreement with the Italian privacy and sensitive data laws and the internal regulations of the AOPD. Informed consent on personal data collection and use for research purpose was obtained from each subject.

2.1. Population Considered

The AOPD is a tertiary teaching hospital in the Italian region of Veneto that covers a population of roughly 350,000 people and records more than 85,000 referrals to the Emergency Department every year.

In this study, only patients admitted to the ED with a negative nasopharyngeal swab and then referred to the ENT emergency room during the aforementioned time frames were considered. All patients underwent high-sensitivity nasopharyngeal swab testing for SARS-CoV-2 upon ED admission, as soon as such tests became available. Those with signs or symptoms suggestive of COVID-19 followed a dedicated triage pathway. Only patients with confirmed negative results and no clinical suspicion of infection were eligible for ENT evaluation.

For each patient, we recorded the date of the ED admission, sex, date of birth, main diagnosis and comorbidities.

Patients with URT disorders (including pharyngitis, laryngitis, otitis, rhinosinusitis, tonsillitis and tracheitis) were included in the study group while those referred for facial trauma or foreign body inhalation formed the control group, as previously described by Ottaviano et al. [11].

2.2. Pollution and Meteorological Data

Daily AP concentration (NO₂, O₃ and PM10 expressed in μg/m³), rainfall depth (mm), air temperature (°C), minimum and maximum relative humidity (%) and the concentration (g/m³) of the most common aeroallergens in the Padua urban area were obtained from environmental monitoring stations operated by the Regional Agency for Environmental Protection and Prevention of the Veneto Region (ARPAV).

The aeroallergens considered were the following:

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Alternaria: A genus of fungi widely distributed in the environment, particularly in decaying vegetation and soil. It is a major source of outdoor mold allergens.

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Betulaceae: A family of trees including birch (Betula spp.), which are significant pollen producers in temperate regions, especially in the spring season.

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Compositae (Asteraceae): A large family of flowering plants including ragweed, mugwort, and others. These produce highly allergenic pollen particularly in late summer and autumn.

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Corylaceae: A botanical family that includes hazel (Corylus spp.) and hornbeam. Pollen from these trees is prevalent in early spring.

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Gramineae (Poaceae): The grass family, a major source of allergenic pollen worldwide. Grass pollens are typically abundant in late spring and early summer.

For O₃ and NO₂, the daily maximum value was considered, for humidity, the daily maximum and minimum values were considered and for all other variables, the average of 24-hourly measurements in the same day were used. To account for temporal trends and delayed effects, we also considered the moving average of mean values over four consecutive days [ma], as well as the lagged effects at one and two days [lag 1] and [lag 2].

2.3. Statistical Analysis

Descriptive statistics are represented by the median (interquartile range) for continuous variables and absolute values (percentage) for categorical variables. An exploratory analysis of environmental variables was carried out by studying the pairwise correlations (Pearson correlation coefficient).

The univariate analyses, which explored the relationships between response variables and risk factors, were carried out by generalized models with Poisson linkage, both in the linear (GLM—Generalized Linear Model) and additive (GAM—Generalized Additive Model) versions.

The model structure for generalized model is

g(μ) = α + Σ_j f_j (X_j)

where g is the link function (in the case of the Poisson model, the link function is the logarithmic function), α is the model intercept, μ is the mean of the response variable conditioned on the explanatory variables and X_j; f_j are the linear functions in the case of the GLM and non-parametric smoothing functions in the case of the GAM.

Multivariate analyses, considering the adjustment for potential confounders (climate variables: temperature, maximum and minimum humidity and rainfall), were carried out with the additive models to consider the possible presence of non-parametric effects. Interactions between timeframes and risk factors were examined with a non-parametric approach using GAMs. This approach was also used to assess the differences between temporal distribution of environmental variables and number of total admissions in the two timeframes.

It is important to note that the use of non-parametric methods, such as GAMs, helps reduce the influence of extreme values (outliers) on the analysis. These values were intentionally retained, as they may represent genuine extreme environmental events that are highly relevant to the objectives of this study.

p-Values were calculated, and 5% was considered the critical level of significance. All analyses were performed using R, a language and environment for statistical computing (R Foundation for Statistical Computing, Vienna, Austria) [12].

3. Results

3.1. Emergency Department Admissions

The total number of admissions in 2017 and 2020/2021 were 7278 and 4594, respectively.

Figure 1 shows the time series of total visits throughout the two years, with the interpolating curves fitted by the GAM.

Table 1. Absolute distribution (percentage) by gender and main diagnosis of emergency room admission; median (IQR) by age.

	2017	2020/2021
Sex
Female	3674 (50%)	2220 (48%)
Male	3604 (50%)	2374 (52%)
Age (years)	47 (29, 67)	52 (31, 71)
Diagnosis
Pharyngitis	210 (3%)	272 (6%)
Laryngitis	273 (3.7%)	91 (2%)
Otitis	433 (6%)	158 (3.4%)
Rhinosinusitis	229 (3.1%)	84 (1.8%)
Tonsillitis	353 (4.8%)	112 (2.4%)
Tracheitis	4 (0.1%)	9 (0.2%)
Traumas	910 (12.5%)	731 (16%)
Others	4866 (66.8%)	3137 (68.2%)
Total admissions	7278 (100%)	4594 (100%)

displays the descriptive statistics of ENT emergency room admissions.

In 2020/2021, there was a reduction in total admissions of 37%. Focusing only on URT inflammatory disease admissions, there was a 52% reduction, decreasing from a total of 1502 admissions in 2017 to 726 in the 2020–2021 timeframe. In both cases, the reduction in admissions in the second timeframe was statistically significant (p-value < 0.001). When considering only admissions for URT inflammations, it was found that in 2017, the disease causing more admissions was otitis (29% of URT admissions), and this percentage decreased to 22% in 2020/2021, being surpassed by pharyngitis (37% of URT admissions).

Considering trauma and foreign bodies, in 2020/2021, there was a 35.6% reduction, decreasing from 4866 to 3137.

Figure 2 highlights the percentage reduction in 2020/2021 compared to 2017 of URT admissions and traumas admissions, respectively.

3.2. Environmental Variables

The distributions of environmental variables have been depicted through box plots in Figure 3. For allergens and precipitation, the graph focuses on non-zero values for better interpretability. The significance of the difference in the distributions of the two timeframes was assessed based on the temporal trends, as follows.

Figure 4, Figure 5 and Figure 6 compare the temporal trend of allergens, climatic variables and pollutants, respectively.

In 2020/2021, levels of Alternaria appeared significantly lower compared to 2017 (p-value < 0.001), especially during summer, when the concentration peaked. The release of Betullaceae and Corylaceae occurred later in the year, reaching higher peaks compared to those recorded in 2017 (p-value < 0.001). The concentrations of Compositae and Gramineae were essentially the same in both periods (p-value = 0.471 and p-value = 0.656, respectively).

No significant differences were detected in the two timeframes for temperature, minimum humidity and rainfall time trends. Maximum humidity was significantly higher in 2020/2021 compared to 2017 (p-value = 0.003). Regarding PM10 levels (Figure 6), the concentration was significantly lower in 2020/2021 compared to 2017 (p-value < 0.001), especially in the months between April and October. The same behavior was observed for NO₂, showing a significantly lower concentration in 2020/2021 (p-value < 0.001). O₃ levels remained substantially unchanged, similarly to the pattern observed for temperature (p-value = 0.284).

Figure 7 shows the scatter plots amongst the environmental variables with significant correlations in 2020/2021 (p-value < 0.05). PM10 results were negatively associated with temperature (correlation = −0.51), whilst they were positively correlated with NO₂ (correlation = 0.61). O₃ was positively associated with temperature and negatively with PM (correlation of 0.83 and −0.54, respectively). Alternaria concentration was positively correlated with temperature (correlation = 0.75), and Betullaceae concentration was positively associated with Corylaceae concentration (correlation = 0.82).

3.3. Environment and URT Admissions

The influence of environmental factors on the daily number of emergency room admissions in 2020/2021 was analyzed. To capture any non-linear effects, while maintaining good interpretability of the results, univariate Poisson-type GAMs were adapted.

Table 2. p-Values of the effects obtained from univariate GAMs.

	Total URT	Otitis	Rhino-Sinusitis	Pharyngitis	Laryngitis	Tonsillitis
Alternaria	<0.001	<0.001	0.108	0.024	0.018	<0.001
Betulaceae	<0.001	0.001	0.275	<0.001	0.314	0.003
Compositae	0.002	0.636	0.004	0.219	0.295	0.003
Corylaceae	<0.001	0.042	0.109	0.002	0.300	0.003
Gramineae	0.001	0.377	0.468	<0.001	0.840	0.017
PM10	0.003	0.407	0.155	0.014	0.992	0.354
O3	<0.001	0.075	0.233	0.004	0.072	0.943
NO2	0.003	0.083	0.960	0.055	0.184	0.265
Temperature	<0.001	0.007	0.047	<0.001	0.113	0.113
Max. Humidity	0.685	0.749	0.316	0.152	0.533	0.640
Min. Humidity	0.046	0.034	0.116	0.113	0.004	0.149
Rainfall	0.443	0.252	0.465	0.086	0.522	0.113

shows the p-values associated with each non-parametric effect. For each model, graphs showing the significant effects are presented in Supplementary Materials Figure S1.1–S1.6.

From the univariate analysis, it emerged that Alternaria had a positive and linear effect on admissions for middle ear infection, pharyngitis, laryngitis and URT diseases, while the effect of Corylaceae showed a decreasing and then increasing trend starting at approximately 60 g/m³ (30 g/m³ for middle ear infection). Betullaceae pollen had an increasing effect after about 40 g/m³ on middle ear infection and respiratory system-related admissions; for the latter, Gramineae pollen started to have an increasing effect at around 50 g/m³. Compositae pollen was a risk factor for sinusitis, tonsillitis and URT admissions up to approximately 5 g/m³.

Regarding pollutants, there was a positive effect of O₃ on total admissions, URT-related admissions and pharyngitis, while NO₂ showed a nearly constant trend. Fine particulate matter had a negative effect on URT-related admissions and pharyngitis.

3.4. Multivariate Analysis

To investigate the effect of pollutants in greater detail, GAMs were fitted for each type of admission and separately for each pollutant, also considering delayed effects of the pollutant and adjustment for possible confounders (climate variables). In order to simplify the model, the non-parametric effects were converted to parametric if the effect was linear, and a stepwise backward selection procedure was adopted. The significant results are displayed in

Table 3. Significant effects obtained from multivariate GAMs are expressed as Incidence Rate Ratios, if parametric; (p) = non-parametric effect was turned into parametric; [ma] = mobile average, mean values in four consecutive days. Graphs showing the non-parametric effect are presented in Supplementary Materials Figure S2.

Risk Factor	Response	Incidence Rate Ratio [95% CI]	p-Value
O3 lag 2 (p)	Pharyngitis	0.879 [0.776; 0.996]	0.042
O3 lag 2 (p)	URT	0.959 [0.927; 0.991]	0.013
PM10 [ma]	Pharyngitis		0.017
PM10 lag 1 (p)	Rinosinusitis	1.354 [1.030; 1.781]	0.035
NO2 [ma]	Pharyngitis		0.015
Alternaria (p)	Otitis	1.114 [1.046; 1.185]	<0.001
Alternaria (p)	Tonsillitis	1.151 [1.068; 1.240]	<0.001
Alternaria (p)	Pharyngitis	0.944 [0.904; 0.985]	0.008
Gramineae (p)	Otitis	0.894 [0.804; 0.994]	0.038
Gramineae (p)	Tonsillitis	0.804 [0.681; 0.948]	0.009
Gramineae	Pharyngitis		0.025
Betulaceae	URT		0.032
Betulaceae	Otitis		0.011
Corylaceae	URT		0.036
Corylaceae	Pharyngitis		0.008

. For parametric effects, results are expressed as Incidence Rate Ratios (IRRs) with 95% confidence intervals (CIs), indicating the multiplicative change in the mean number of ED admissions per 10-unit increase in the exposure variable. When effects were non-parametric, they could not be summarized as IRRs and are instead graphically represented in the Supplementary Materials (Figure S2).

A significant effect of the cumulative mean value of PM10 was found for pharyngitis. The effect showed an increasing trend from around 30 μg/m³. A positive, linear effect of the PM10 delayed at day 1 for rhinosinusitis was found, too (an increase of 10 μg/m³ of PM10 delayed at day 1 is associated with an 35.4% [0.30–78.1] increase in the average number of rhinosinusitis admissions). A positive and linear effect of Alternaria was observed for tonsillitis and otitis admissions (increase of 15.1% [0.7–24.0] and 11.4% [0.5–18.5], respectively), confirming the results of the univariate analysis. Otitis was also positively influenced by the concentration of Betulaceae starting around 30 g/m³, as were URT admissions. Corylaceae showed a positive effect on pharyngitis and URT admissions starting around 60 g/m³.

3.5. Model Comparison Between 2017 and 2020/2021

A further comparison of the multivariate models investigating the effects of pollutants including the interaction between timeframe and risk factor was performed. The models were constructed by initially including lagged effects and confounders; they were then simplified by removing non-significant terms. The significant results are displayed in

Table 4. Models that consider 2017 and 2020/2021 data by including the interaction between timeframe and risk factor. Significant effects obtained from multivariate GAM are expressed as Incidence Rate Ratioa, if parametric; (p) = non-parametric effect was turned into parametric; [ma] = mobile average, mean values in four consecutive days. Graphs showing the non-parametric effect are presented in Supplementary Materials Figure S3.

Risk Factor	Response	Incidence Rate Ratio 2017 [95% CI]	Incidence Rate Ratio 2020/2021 [95% CI]	p-Value 2017	p-Value 2020/2021
PM10 [ma]	URT			0.037	0.159
PM10 [ma] (p)	Otitis media	1.047 [1.001; 1.094]	0.939 [0.857; 1.030]	0.046	0.181
PM10 [ma]	Pharyngitis			0.347	0.001
PM10 [ma] (p)	Tonsillitis	1.209 [1.054; 1.388]	1.234 [1.041; 1.463]	0.007	0.015
NO2 (p)	Otitis media	1.067 [1.017; 1.120]	0.923 [0.843; 1.009]	0.009	0.078
Alternaria (p)	URT	0.971 [0.958; 0.983]	1.032 [1.013; 1.051]	<0.001	0.001
Alternaria (p)	Otitis media	0.958 [0.934; 0.983]	1.047 [1.008; 1.088]	0.001	0.018
Alternaria (p)	Rinosinusitis	0.992 [0.959; 1.026]	1.064 [1.009; 1.123]	0.652	0.023
Alternaria (p)	Pharyngitis	0.940 [0.910; 0.971]	0.974 [0.940; 1.008]	<0.001	0.131
Alternaria (p)	Tonsillitis	0.987 [0.962; 1.013]	1.079 [1.035; 1.125]	0.314	<0.001
Betulacee	URT			0.033	<0.001
Betulacee	Otitis media			0.001	<0.001
Corylaceae	URT			0.005	<0.001
Corylaceae	Otitis media			<0.001	0.064
Corylaceae	Pharyngitis			0.978	0.003
Corylaceae	Tonsillitis			0.870	0.007

. The parametric effects are presented as IRRs. When effects were non-parametric, they could not be summarized as IRRs and are instead graphically represented in the Supplementary Materials Figure S3.

Regarding pollutants, the cumulative mean value of PM10 maintained its positive effect on tonsillitis in both time periods analyzed, while its effect on pharyngitis was detected only during the 2020/2021 period. The NO₂ effect on otitis media was not confirmed in the second timeframe, while it presented a positive linear effect in 2017.

Alternaria showed a significant positive linear effect in 2020/2021 on most URT-related admissions. Betullaceae concentration presented a risk effect for middle ear infection and URT-related admissions in 2020/2021 after about 50 g/m³, while in 2017, the effect was almost linear. Corylaceae retained their effect on the total number of admissions in the two periods: in 2017, the effect was linear, whilst in 2020/2021, it showed a decreasing and then increasing trend starting around approximately 60 g/m³.

4. Discussion

4.1. Reduction in ENT ED Accesses

Our research primarily examined how the Italian COVID-19 lockdown affected the number of admissions for ENT-related disorders at a tertiary emergency department in the Veneto Region. As expected, we found a consistent overall reduction in the number of patients admitted to our ED: the number of overall admissions was reduced by over a third while the number of specific admissions for inflammatory diseases of the URT was reduced by over half. This was in line with the previous findings in other tertiary referral centers in Italy that described a reduction in ENT-related ED admissions between 62.16 and 71.5% [13,14]. These studies, however, only focused on the earlier months of the pandemic. Similar trends have also been described in the pediatric population, with a significant decrease in patients’ attendance to the pediatric ED, especially in cases caused by ENT-related disorders [15].

It was challenging to find a comprehensive explanation for the effect of the pandemic on ENT-emergencies. However, we had to consider that at the onset of the pandemic, the Veneto Region implemented healthcare policies aimed at discouraging non-urgent visits to hospital clinics and in-person visits to family practitioners. This might have resulted in several patients not seeking medical treatment for minor issues. The reduction could also be due to the fear of contracting the virus in hospitals or outpatient clinics. These elements, along with restricted access to consultations and the increased use of telemedicine [16], might have led to two outcomes: a reduction in the total number of ENT-ED admissions and the selection of only the most complex cases. Similar scenarios have already been described in previous investigations by Pontillo et al. [17] and Gallo et al. [18], emphasizing the increase in complex or late-diagnosed cases and emergency/urgent surgeries.

4.2. Environmental Pollutants and URT Manifestations

In parallel with the reduction in admissions to the ED, there was a significant reduction in AP, in particular PM and NO₂. Road traffic was the major anthropic component that showed a clear reduction relative to the lockdown period. The Italian national travelling reduction was approximately 80% compared to the pre-COVID-19 period for light vehicles and approximately 40% for heavy vehicles [19]. However, road traffic is only one source of particulate matter production. Other significant emissions, such as those from domestic heating systems, agricultural activities and animal farms were not affected by restrictions and were not as strongly regulated as road traffic [20].

Considering PM, which had lower concentrations in 2020/2021 than in 2017, it is reasonable to assume that lower PM10 levels probably resulted in milder manifestations of upper respiratory tract diseases. In fact, their incremental effect on total admissions and otitis media was not confirmed in 2020/2021. Nevertheless, the effect of increasing admissions for tonsillitis and pharyngitis remained, particularly when PM10 concentrations exceeded 40 μg/m³. This was in line with a recent meta-analysis that confirmed how larger particles might trigger upper respiratory infections more than smaller ones [21]. On the other hand, O₃ concentrations were similar in the two years and the impact of this pollutant on URT diseases seemed limited. NO₂ levels were lower in 2020/2021 and their role in otitis media was not confirmed by the multivariate analysis in this timeframe.

4.3. Aeroallergens and URT Manifestations

Regarding aeroallergens, it is interesting to note that Alternaria levels appeared lower in 2020/2021. Alternaria is usually present in lower atmospheric concentrations compared to other allergenic airborne spores but is responsible for the highest rate of sensitization amongst atopic patients [22,23]. Exposure to Alternaria primarily occurs outdoors since fungal spores largely originate from agricultural lands. Seasonal variations are influenced by climate [24]. However, its presence as an indoor pollutant should not be overlooked, as it remains a dominant indoor fungus, alongside Cladosporium and Penicillium [25].

Urban areas typically have higher pollution levels and may also influence spore production and allergenicity. Increased levels of PM10 are linked to a rise in airborne fungi [26], and elevated CO₂ concentrations can triple the spore production of Alternaria species, doubling the number of allergenic proteins [27].

During the pandemic, reduced pollution in urban areas likely contributed to lower Alternaria levels in Padua. Despite this, it is worth noting that home confinement and mask usage only partly diminished Alternaria’s role in URT diseases. It emerged as a significant independent factor in conditions such as otitis media, tonsillitis and URT related diseases. Differently from Alternaria, Gramineae and Compositae levels did not have a significant change in the first year of the COVID-19 pandemic. Their pollens are a major cause of seasonal allergies in temperate climates, affecting up to 30% of the population in Western countries [28]. Although the levels of these allergens did not decrease as much as AP, the increased use of masks and indoor activities might be an explanation for the significant reduction in rhinitis/rhinosinusitis (over 60% in our series) and the reason for the decreasing trend of allergic rhinitis found during this period [29]. The protective effect of confinement, however, might have been mitigated in the case of Betulaceae and Corylaceae in view of the higher levels of pollen that were recorded. Their peculiar effect on total URT, tonsillitis and pharyngitis admissions could be partially explained by the trend in the spring and summer months: in fact, both had higher and later peaks in 2020/2021. In particular, the delayed peak in their pollen’s concentrations observed in 2020/2021 compared to 2017 could plausibly be attributed to a slight delay in the seasonal rise in temperatures, which plays a key role in triggering pollen release for both families. The fact that they reached higher levels during a period of loosening of the restrictions, albeit with an almost constant use of masks even outdoors, may have contributed to the peculiar distributions of their effect, which appear to be decreasing up to a certain critical threshold and then reach significantly higher incremental trends when compared to 2017.

Social distancing and isolation, the use of masks and implemented hand hygiene measures were responsible for the significant decrease in new diagnoses of otitis media during the lockdown periods as recently demonstrated in a meta-analysis by Warner et al. [30]. In our cohort, we observed a reduction of almost two-thirds in the number of otitis admissions when compared to 2017. When looking at the effect of pollutants on otitis, it is interesting to highlight that only Alternaria and Betullaceae maintained their significant effect in the multivariate analysis in 2020/2021, whilst the other allergens and APs lost their level of significance, probably mitigated by the reduction in AP levels and the aforementioned behavioral measures.

The aim of the comparison between the two years was to determine whether different living conditions, in this case markedly changed due to the pandemic, lead to different associations between pollutants and admissions to emergency rooms. Although it was not easy to unambiguously determine what caused the differences that emerged, the present study supports the current literature and confirms the harmful effects of pollution on health. While climatic factors, such as temperature and humidity, are not directly controllable by human activity, it is possible to act on other elements that have an influence on public health. In addition to carefully choosing the trees that will be placed in the city to avoid harmful aeroallergens as much as possible, it is important to take measures to reduce air pollution and to raise awareness among the population for responsible behavior that may limit the anthropogenic impact on the environment, also in the interest of our own health.

The interplay between environmental changes, public health and clinical outcomes underscores the need for interdisciplinary collaboration. To better understand the environmental factors influencing public health, it is essential to foster cooperation among medical professionals, public health providers, environmental researchers and experts in animal health. Such an integrated approach would enable a more comprehensive analysis of how human activities and environmental modifications contribute to health outcomes, paving the way for evidence-based interventions and sustainable solutions.

Moreover, although this study focused on otorhinolaryngological pathologies, future research could expand the scope by applying the same statistical approach to other health domains, particularly cardiovascular diseases. There is increasing evidence that air pollutants (especially particulate matter) may contribute to cardiovascular morbidity [31,32]. Including these conditions in future analyses could provide a broader understanding of the impact of air pollution on human health and further strengthen the public health relevance of environmental monitoring.

The main limitations of the present study are its retrospective and monocentric design and the lack of comparison with data collected from other ENT emergency departments. Considering different time frames over several years and with different ENT centers could lead to more robust results. 

5. Conclusions

The COVID-19 lockdown in the Veneto Region of Italy led to a significant decrease in the number of patients admitted to the emergency department (ED) for ENT-related disorders. This reduction was consistent with findings from other regions in Italy and was particularly notable for URT inflammatory diseases. The lockdown also resulted in decreased air pollution, particularly in PM and NO₂ levels. While certain allergens such as Alternaria showed lower levels during the lockdown, they continued to play a significant role in ENT disorders such as otitis media and tonsillitis. Other allergens, such as Betulaceae and Corylaceae, had higher peaks compared to 2017 and showed a significant and independent effect particularly regarding the total number of URT accesses, tonsillitis and pharyngitis. Social distancing, mask-wearing and enhanced hygiene practices likely contributed to a significant decrease in URT infections, especially in otitis media during the lockdown period.

These findings highlight the harmful effects of pollution on health even during global pandemic and underline the importance of reducing air pollution and promoting responsible behavior to minimize anthropogenic environmental impacts for better public-health outcomes.

Moreover, this study supported the value of integrating clinical data with environmental monitoring and advanced statistical modeling to elucidate complex cause–effect relationships in selected settings. This can contribute to the growing body of evidence supporting the inclusion of environmental health indicators in public health planning. In light of these findings, there is a rationale for deeply investigating the adoption of long-term strategies aimed at reducing pollutant emissions, regulating allergenic vegetation in urban planning and maintaining certain protective behaviors. Public health campaigns should also aim to raise awareness about the environmental determinants of ENT diseases.

While the study was limited by its retrospective, monocentric design and focused on a specific geographic area, its results lay the groundwork for broader investigations. Future research should aim to confirm these findings in other populations and expand the scope to other environmentally sensitive health conditions, such as cardiovascular and respiratory diseases or animal well-being. Multi-center, longitudinal studies with integrated environmental and clinical datasets would be instrumental in shaping evidence-based policy and reinforcing the environmental dimension of public health.