Average NO2 Concentrations Research Articles

COVID-19 Outbreak in Lombardy, Italy: An Analysis of the Short-Term Role of Air Pollution and Meteorological Factors

Background: Short-term exposure to air pollution, as well as to climate variables could be linked to a higher incidence of respiratory viral diseases. The objective of the study is to assess the short-term impact of air pollution and climate on COVID19 incidence in Lombardy (Italy), during the initial outbreak.Methods: The daily number of COVID19 cases in Lombardy from February 25th to March 10th 2020, and the daily average concentrations of particulate matter (PM10, PM2·5), O3, SO2, and NO2 together with climate variables (temperature, relative humidity – RH%, wind speed, precipitation), were analyzed. A mixed model with a logarithm transformation as link function was applied to evaluate the relationship between all the variables. Additionally, change points (Break Points; BP) in the relationship between incident cases and air pollution or climatic factors were estimated.Findings: The analysis showed a two-phase effect of PM10 on COVID19 incidence, with a negative association at the beginning of the examined period and a positive one later on, while a positive relationship was observed for O3. The COVID19 spread in Lombardy showed to be influenced positively by RH%, and negatively by wind speed. A BP at 40 µg/m3 was observed for PM10 at lag8, and for O3 at lags 3-8 and 10.Interpretation: PM10, O3, RH% and wind speed showed a short-term association with the COVID19 incidence. Air pollution and climate conditions should be considered as part of an integrated approach when containment measures against SARS-CoV-2 are adopted.Funding: The study did not receive any fund.Declaration of Interests: The Authors declare no conflict of interest.

Susceptibility of individuals with chronic obstructive pulmonary disease to respiratory inflammation associated with short-term exposure to ambient air pollution: A panel study in Beijing

BackgroundChronic obstructive pulmonary disease (COPD) is a leading cause of death worldwide. There is no clear evidence of whether COPD patients are more susceptible to respiratory inflammation associated with short-term exposure to air pollutants than those without COPD. ObjectivesThis study directly compared air pollutant-associated respiratory inflammation between COPD patients and healthy controls. MethodsThis study is based on the COPDB panel study (COPD in Beijing). Fractional exhaled nitric oxide (FeNO) was repeatedly measured in 53 COPD patients and 82 healthy controls at up to four clinical visits. Concentrations of carbon monoxide (CO), nitrogen monoxide, nitrogen dioxide (NO2), sulfur dioxide (SO2), fine particulate matter (PM2.5), black carbon (BC), ultrafine particles (UFPs), and accumulated-mode particles (Acc) were monitored continuously at a fixed-site monitoring station. Linear mixed-effects models were used to compare the associations between ln-transformed FeNO and average 1–23 h concentrations of air pollutants before the clinical visits. ResultsFeNO was positively associated with interquartile range (IQR) increases in average concentrations of CO, NO2, SO2, BC, UFPs, and Acc in all participants, with the strongest associations in different time-windows (range from 6.6% for average 1 h NO2 exposure to 32.1% for average 7 h SO2 exposure). Associations between FeNO and average 13–23 h PM2.5 exposure differed significantly according to COPD status. Increases in FeNO associated with average 1–2 h NO exposure were significant in COPD patients (range 8.9–10.2%), while the associations were nonsignificant in healthy controls. Associations between FeNO and average 1–23 h CO and SO2 exposure tended to be higher in COPD patients than in healthy controls, although the differences were not significant. UFPs-associated respiratory inflammation was robust in both subgroups. ConclusionsCOPD patients are more susceptible to respiratory inflammation following PM2.5, NO, CO, and SO2 exposure than individuals without COPD.

Impact on Air Quality of the COVID-19 Lockdown in the Urban Area of Palermo (Italy)

At the end of 2019, the first cases of coronavirus disease (COVID-19) were reported in Wuhan, China. Thereafter, the number of infected people increased rapidly, and the outbreak turned into a national crisis, with infected individuals all over the country. The COVID-19 global pandemic produced extreme changes in human behavior that affected air quality. Human mobility and production activities decreased significantly, and many regions recorded significant reductions in air pollution. The goal of our investigation was to evaluate the impact of the COVID-19 lockdown on the concentrations of the main air pollutants in the urban area of Palermo (Italy). In this study, the trends in the average concentrations of CO, NO2, O3, and PM10 in the air from 1 January 2020 to 31 July 2020 were compared with the corresponding average values detected at the same monitoring stations in Palermo during the previous five years (2015–2019). During the lockdown period (10 March–30 April), we observed a decrease in the concentrations of CO, NO2, and particulate matter (PM)10, calculated to be about 51%, 50%, and 45%, respectively. This confirms that air pollution in an urban area is predominantly linked to vehicular traffic.

Variability of Nitrogen Oxides in the Atmospheric Surface Layer near Saint Petersburg

The results of measurements of surface concentrations of nitrogen oxides NOx (NO and NO2) performed at the atmospheric monitoring station near Saint Petersburg (Petergof, 59.88° N, 29.83° E) in 2012–2018 are presented. The main patterns of the temporal variability of NOx concentrations typical for the urban atmosphere of a large megacity (seasonal, daily, and weekly variations) are revealed. On average, NOx concentrations in summer are lower than in the cold season. The average daily variations are characterized by two pronounced peaks: in the morning and late at night, which are separated by the periods of relatively low concentrations during the day and early in the morning. The weekly variations in NOx concentration due to the cyclic pattern of urban economic and business activity are manifested in a noticeable decrease in the average NOx concentration on Sunday relative to its maximum level on weekdays (by 17% for NO2 and by 33% for NO). Based on the distribution of the average NOx concentration depending on the directions of surface wind, a rough estimate of the average NO2 concentration in Saint Petersburg was obtained: 41 µg/m3, which is close to the average annual maximum permissible concentration (40 µg/m3).

Initial COVID-19 Transmissibility and Three Gaseous Air Pollutants (NO2, SO2, and CO): A Nationwide Ecological Study in China.

In this study, we conducted an ecological study to examine their effects in the early phase of the pandemic (from December 2019 to February 2020) in China. We found that the associations between the average concentrations of NO2, SO2, and CO and the COVID-19 transmissibility are not statistically clear.

Urban Air Pollution May Enhance COVID-19 Case-Fatality and Mortality Rates in the United States

BackgroundThe novel human coronavirus disease 2019 (COVID-19) pandemic has claimed more than 600,000 lives worldwide, causing tremendous public health, social, and economic damages. Although the risk factors of COVID-19 are still under investigation, environmental factors, such as urban air pollution, may play an important role in increasing population susceptibility to COVID-19 pathogenesis. MethodsWe conducted a cross-sectional nationwide study using zero-inflated negative binomial models to estimate the association between long-term (2010–2016) county-level exposures to NO2, PM2.5, and O3 and county-level COVID-19 case-fatality and mortality rates in the United States. We used both single- and multi-pollutant models and controlled for spatial trends and a comprehensive set of potential confounders, including state-level test positive rate, county-level health care capacity, phase of epidemic, population mobility, population density, sociodemographics, socioeconomic status, race and ethnicity, behavioral risk factors, and meteorology. ResultsFrom January 22, 2020, to July 17, 2020, 3,659,828 COVID-19 cases and 138,552 deaths were reported in 3,076 US counties, with an overall observed case-fatality rate of 3.8%. County-level average NO2 concentrations were positively associated with both COVID-19 case-fatality rate and mortality rate in single-, bi-, and tri-pollutant models. When adjusted for co-pollutants, per interquartile-range (IQR) increase in NO2 (4.6 ppb), COVID-19 case-fatality rate and mortality rate were associated with an increase of 11.3% (95% CI 4.9%–18.2%) and 16.2% (95% CI 8.7%–24.0%), respectively. We did not observe significant associations between COVID-19 case-fatality rate and long-term exposure to PM2.5 or O3, although per IQR increase in PM2.5 (2.6 μg/m3) was marginally associated, with a 14.9% (95% CI 0.0%–31.9%) increase in COVID-19 mortality rate when adjusted for co-pollutants. DiscussionLong-term exposure to NO2, which largely arises from urban combustion sources such as traffic, may enhance susceptibility to severe COVID-19 outcomes, independent of long-term PM2.5 and O3 exposure. The results support targeted public health actions to protect residents from COVID-19 in heavily polluted regions with historically high NO2 levels. Continuation of current efforts to lower traffic emissions and ambient air pollution may be an important component of reducing population-level risk of COVID-19 case fatality and mortality.

Impacts of nationwide lockdown due to COVID-19 outbreak on air quality in Bangladesh: a spatiotemporal analysis.

In Bangladesh, a nationwide lockdown was imposed on 26 March 2020, due to the COVID-19 pandemic. Due to restricted emissions, it was hypothesized that the air quality has been improved during lockdown throughout the country. The study is intended to assess the impact of nationwide lockdown measures on air quality in Bangladesh. We analyzed satellite data for four different air pollutants (NO2, SO2, CO, and O3) to assess the changes in the atmospheric concentrations of pollutants in major cities as well as across the country. In this study, the concentrations of NO2, SO2, CO, and O3 from 1 February to 30 May of the year 2019 and 2020 were analyzed. The average SO2 and NO2 concentrations were decreased by 43 and 40%, respectively, while tropospheric O3 were found to be increased with a maximum of > 7%. Among the major cities, Dhaka, Gazipur, Chattogram, and Narayanganj were found to be more influenced by the restricted emissions. In Dhaka, NO2 and SO2 concentrations were decreased approximately by 69 and 67%, respectively. Our analysis reveals that NO2 concentrations are highly correlated with the regional COVID-19 cases (r = 0.74). The study concludes that the lockdown measures significantly reduced air pollution because of reduced vehicular and industrial emissions in Bangladesh.Electronic supplementary materialThe online version of this article (10.1007/s11869-020-00940-5) contains supplementary material, which is available to authorized users.

The Great Smog Month and Spatial and Monthly Variation in Air Quality in Ambient Air in Delhi, India.

Background.In recent years, poor urban air quality in Delhi, India has gained significant attention. Episodic events including crop stubble burning and Diwali celebrations are considered major factors in the worsening quality of ambient air.Objective.This study aimed to investigate spatial and monthly variation as well as the role of episodic events in ambient air quality in Delhi, including the ‘Great Smog' month of November 2017.Methods.Monitoring of air pollutants (particulate matter (PM10, PM2.5, PM1) and nitrogen dioxide (NO2)) was carried out at three distinct locations of Delhi from April 2017–February 2018. The concentration of NO2 was measured using a modified Jacob and Hochheiser method and PM was measured using a GRIMM aerosol spectrometer. Air quality index was also determined to identify the effects of air pollution on human health.Results.Overall, the levels of air pollution were found to be approximately 2.1–3.2 times higher along a traffic intersection and about 1.4–2.0 times higher in a commercial area compared with an institutional area. The highest average monthly concentrations of PM10, PM2.5, PM1 and NO2 were 768, 374, 298 and 149 μg/m3, respectively, during the Great Smog month of November 2017. November and August were recorded as the most polluted and cleanest months, respectively, in the city. Generally, poor to severe categories of the air quality index (AQI) were obtained from October to February. Higher concentrations during November were attributed to stubble burning in the nearby states of Delhi with the additive effect of fireworks during Diwali celebrations.Conclusions.Severe ambient air quality as observed in the present study is a serious matter of concern for the health of Delhi's population. To control spikes in poor air quality during episodic events, it is imperative to raise awareness among farmers regarding the severe health hazards of stubble burning.Competing Interests.The authors declare no competing financial interests.

Association of long-term exposure to ambient air pollutants with prolonged sleep latency: The Henan Rural Cohort Study

BackgroundProlonged sleep latency is associated with far-reaching public health consequences. Although evidence about the effect of air pollution on sleep problem has been shown, the effect on sleep latency remained unknown. The study aimed to analyze the association between long-term exposure to air pollution and prolonged sleep latency in rural China. MethodsIn all, 27935 participants were included in the study from Henan Rural Cohort Study. A satellite-based spatiotemporal model was used to evaluate the 3-year average concentration of air pollutants at the home address of participants before the baseline survey. Air pollutants included NO2 (nitrogen dioxide), PM1 (particulate matter with aerodynamic diameters ≤1 μm), PM2.5 (particulate matter with aerodynamic diameters ≤ 2.5 μm), and PM10 (particulate matter with aerodynamic diametes ≤ 10 μm). A logistic regression model was conducted to assess the odds ratio (OR) and 95% confidence interval (95% CI) between air pollutants and prolonged sleep latency. ResultsThere were 5825 (20.85%) participants with prolonged sleep latency. The average concentration of NO2, PM1, PM2.5, and PM10 were 38.22 (2.54) μg/m3, 56.29 (1.75) μg/m3, 72.30 (1.87) μg/m3, and 130.01 (4.58) μg/m3. The odds ratio (95%CI) of prolonged sleep latency with an IQR increase of NO2, PM1, PM2.5, and PM10 were 1.59 (1.33–1.90), 1.23 (1.13–1.33), 1.28 (1.13–1.45) and 1.43 (1.22–1.67). The stratified analysis showed the effect of air pollutants was stronger among those with stroke. ConclusionLong-term exposure to NO2, PM1, PM2.5 and PM10 were associated with prolonged sleep latency. The adverse impact of air pollution should be considered when treating sleep problems.

COVID-19 lockdown and its impact on tropospheric NO2 concentrations over India using satellite-based data

The World Health Organization has declared the COVID-19 pandemic a global public health emergency. Many countries of the world, including India, closed their borders and imposed a nationwide lockdown. In India, the lockdown was declared on March 24 for 21 days (March 25–April 14, 2020) and was later extended until May 3, 2020. During the lockdown, all major anthropogenic activities, which contribute to atmospheric pollution (such as industries, vehicles, and businesses), were restricted. The current study examines the impact of the lockdown on tropospheric NO2 concentrations. Satellite-based ozone monitoring instrument sensor data were analyzed in order to investigate the variations in tropospheric NO2 concentrations. The results showed that from March 1 to 21, 2020, the average tropospheric NO2 concentration was 214.4 ×1013 molecule cm−2 over India, and it subsequently decreased by 12.1% over the next four weeks. An increase of 0.8% in tropospheric NO2 concentrations was observed for the same period in 2019 and hence, the reduced tropospheric NO2 concentrations can be attributed to restricted anthropogenic activities during the lockdown. In the absence of significant activities, the contribution of various sources was estimated, and the emissions from biomass burning were identified as a major source of tropospheric NO2 during the lockdown. The findings of this study provide an opportunity to understand the mechanism of tropospheric NO2 emissions over India, in order to improve air quality modeling and management strategies.

Locations of Adolescent Physical Activity in an Urban Environment and Their Associations with Air Pollution and Lung Function.

Rationale: Physical activity while being exposed to high concentrations of air pollution may lead to greater inhalation of pollutant particles and gases. Thus, owing to features of the built city environment, specific locations where physical activity take place may put individuals at increased risk for harmful inhaled exposures leading to decrements in lung function.Objectives: The objectives were to determine locations throughout an urban landscape where children engage in moderate to vigorous activity (MVA). We hypothesized that outdoor activity would be associated with increased exposure to air pollution and reduced lung function.Methods: Children aged 9-14 years living in New York City (NYC) (n = 151) wore global positioning system devices and wrist accelerometers for two 24-hour periods. Time-stamped global positioning system points and accelerometer data were aggregated and mapped using ArcGIS to determine locations where children engaged in MVA. Location-specific particulate matter <2.5 microns and nitrogen dioxide (NO2) was determined based on land use regression models of street-level pollution. Temporal air pollution exposure was determined based on daily concentrations collected at one central site in NYC. Forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and forced expiratory flow, midexpiratory phase (FEF25-75) were collected following each 24-hour period. Data were analyzed using multivariable linear regression models to examine associations between MVA time and both lung function and air pollution in separate models. Additionally, a multiplicative interaction term (MVA time × season) was included to test whether the association between MVA time and lung function outcomes varied by warmer versus colder months.Results: On average, children spent less MVA time outdoors (38.2 ± 39.6 min/d) compared with indoors (71.9 ± 74.7 min/d, P < 0.01), regardless of season. The majority of outdoor MVA occurred along sidewalks and roadbeds (30.2 ± 33.3 min/d, 76.9% of outdoor) where annual average concentrations of NO2 were relatively high. Interquartile range (IQR) increase in outdoor MVA time (44 min) was associated with higher levels of annual average NO2 (P < 0.01) but not particulate matter <2.5 microns. In warmer months, for IQR increase in outdoor MVA time, children had 1.41% lower FEV1/FVC (95% confidence interval [95% CI], -2.46 to -0.36) and 4.40% lower percent predicted FEF25-75 (95% CI, -8.02 to -0.78). These results persisted even after adjustment for location-specific annual average concentrations of NO2. No association was observed between MVA time and lung function in colder months (P > 0.05), and a formal test for interaction (MVA time × season) was significant (P value for interaction = 0.01 and 0.03 for FEV1/FVC and FEF25-75, respectively).Conclusions: Children in NYC spent less time active outdoors compared with indoors. Outdoor activity was greatest near traffic sources and associated with higher annual average concentrations of NO2. In warmer months, outdoor activity was associated with lower lung function, but this association did not appear to be mediated by higher exposure to outdoor pollution during exercise.

Abstract 3395: Commute patterns, residential traffic-related air pollution, and lung cancer risk in the prospective UK Biobank cohort study

Abstract Introduction: Commuting to and from work is a daily activity that exposes millions of people to lung carcinogens such as particulate matter, polycyclic aromatic hydrocarbons, and other constituents of traffic-related air pollution (TRAP). Lung cancer is a global health burden and one of the most common malignancies among industrialized western countries such as the United Kingdom (UK). Few epidemiologic studies of TRAP and lung cancer consider the contribution of commute characteristics. To further investigate, we assessed associations between commute patterns, residential nitrogen dioxide (NO2; a surrogate marker for TRAP), and lung cancer risk in the prospective UK Biobank cohort study. Methods: We analyzed 234,124 employed participants at baseline in 2006-2010. There were 493 incident lung cancer cases diagnosed over an average 7-year follow-up. Subjects were cross-classified into exclusive categories of commute mode (automobile, public transportation, walking, cycling, active mixture, and other mixture) and frequency (regular: &amp;lt;5, often: ≥5 work-bound trips/week). Annual average residential NO2 concentrations in 2005-2007 were estimated from land use regression. Cox regression models were used to estimate associations between commute patterns, quartiles of NO2, and incident lung cancer, adjusted for age, sex, smoking status, race/ethnicity, study center, body mass index, annual income, commute distance, and alcohol intake. Additional analyses were stratified by age, sex, smoking status, NO2 (&amp;gt;, ≤ median2005=28.3 µg/m3) and main job duration (&amp;gt;, ≤10 years). Effect modification was tested using interaction terms. Results: Most participants only used automobiles to commute (56.5%), while 8.3% only used public transportation (e.g., buses, light-rail, subways), 2.2% only cycled, and 5.0% only walked. Compared to regular automobile use, commuting often by public transportation was strongly associated with increased lung cancer risk (HR=1.68, 95% CI: 1.14-2.47). The association was nominally stronger among high-NO2 residences, men, and ever-smokers, while similar by job duration. There was evidence for effect modification of the association by residential NO2 (p-interaction=0.03) and sex-smoking status (p-interactions=0.03 and 0.09 for former- and current-smoking men, respectively). The other commute categories were not associated with risk. Furthermore, there was a positive exposure-response relationship with NO2 (HRQ2=1.23, 95% CI:0.91-1.65; HRQ3=1.51, 95% CI:1.12-2.03; HRQ4=1.61, 95% CI:1.15-2.27; p-trend=2.1 × 10−3). Conclusions: Our findings suggest that commuters who often use public transportation have elevated lung cancer risk, possibly driven by time spent in transit microenvironments with high TRAP-levels. Although there are health benefits of public transit use, the competing risk of lung cancer warrants consideration. Citation Format: Jason Yat-Yang Wong, Rena Jones, Bryan Bassig, Batel Blechter, Wei Hu, Bu-tian Ji, Nathaniel Rothman, Qing Lan. Commute patterns, residential traffic-related air pollution, and lung cancer risk in the prospective UK Biobank cohort study [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3395.

Air quality variations in Northern South America during the COVID-19 lockdown

Lockdown measures led to air pollution decrease in several countries around the world such as China and India, whereas other regions experimented an increase in pollutant concentrations. Northern South America (NSA) was one of those areas where pollution changed during lockdown due to high fire activity. This study aims to analyze, for the first time in NSA, the behavior of selected criteria air pollutants during the implementation of the SARS-CoV-2 lockdown in two high populated cities of the region: Bogotá and Medellín in Colombia. A set of tools including surface measurements, as well as satellite and modeled data were used. 24-hour average concentrations of PM10, PM2.5, and NO2 were collected from air quality stations for the lockdown period ranging from February 21 to June 30, 2020. The Copernicus Atmosphere Monitoring Service (CAMS) was used to analyze the fire flux OC as a biomass burning (BB) indicator, and tropospheric NO2 concentrations were retrieved from TROPOMI. The HYSPLIT model was used to analyze back trajectories and fire data were obtained from MODIS sensor measurements. Our analysis shows short-term background NO2, PM10, and PM2.5 concentration reductions of 60%, 44%, and 40%, respectively, for the strict lockdown; and 62%, 58%, and 69% for the relaxed lockdown. Corresponding long-term reductions were of 50%, 32%, and 9% for the strict lockdown; and 37%, 29%, and 19% for the relaxed lockdown. Regional BB increased PM2.5 concentrations by 20 μg/m3 during the strict lockdown, and the Saharan dust event increased PM10 concentrations up to 168 μg/m3 in Bogotá, and 104 μg/m3 in Medellín, bringing an additional risk of morbidity and mortality for population. Regional BB has several causes that need to be properly managed to benefit local air quality improvement plans. Future cleaner transport policies equivalent to reduced lockdown mobility could bring pollution close to WHO guidelines.

Short-term effects of ambient nitrogen dioxide on years of life lost in 48 major Chinese cities, 2013–2017

BackgroundEvidence on the acute effect of short-term exposure to nitrogen dioxide (NO2) on years of life lost (YLL) is rare, especially in multicity setting. MethodsWe conducted a time series study among 48 major Chinese cities covering more than 403 million people from 2013 to 2017. The relative percentage changes of NO2-YLL were estimated by generalized additive models in each city, then were pooled to generate average effects using random-effect models. In addition, stratified analyses by individual demographic factors and temperature as well as meta-regression analyses incorporating city-specific air pollutant concentrations, meteorological conditions, and socioeconomic indicators were performed to explore potential effect modification. ResultsA 10 μg/m3 increase in two-day moving average (lag01) NO2 concentration was associated with 0.64% (95% CI: 0.47%, 0.81%), 0.47% (95% CI: 0.27%, 0.68%), and 0.68% (95% CI: 0.34%, 1.02%) relative increments in YLL due to nonaccidental causes, cardiovascular diseases (CVD), and respiratory diseases (RD), respectively. These associations were generally robust to the adjustment of co-pollutants, except for NO2-CVD that might be confounded by fine particulate matter. The increased YLL induced by NO2 were more pronounced in elderly people, hotter days, and cities characterized by less severe air pollution or higher temperature. ConclusionsOur results demonstrated robust evidence on the associations between NO2 exposure and YLL due to nonaccidental causes, CVD, and RD, which provided novel evidence to better understand the disease burden related to NO2 pollution and to facilitate allocation of health resources targeting high-risk subpopulation.

Association of short-term exposure to air pollution with mortality in a middle eastern tourist city

This study investigated the association of short-term exposure to PM10, PM2.5, NO2, O3, and CO with daily all-cause, cardiovascular, ischemic heart disease (IHD), cerebrovascular, and respiratory deaths in Mashhad, a tourist megacity in Iran (2014–2018). A distributed-lag-day, nonlinear model (DLNM) and generalized additive model (GAM) based on the quasi-Poisson distribution were used to explore the exposure-lag-day-response associations. The average (± standard deviation) concentrations of PM10, PM2.5, NO2, O3, and CO were 67.1 (± 35.5), 29.6 (± 14.2), 57.3 (± 24.1), 55.9 (± 16.9), and 1907.6 (± 1362.7) μg/m3, respectively. NO2 was associated with IHD mortality in lag-days 0 to 0–7, and lag-day 1. The relative risks (RRs) for a 10 μg/m3 increase in NO2 ranged from 1.01 (95% CI 0.93, 1.11) at lag-day 0 to 1.04 (95% CI 0.94, 1.16) and 1.03 (95% CI 0.93, 1.14) for lag-day 0–1 (cumulative) and lag-day 1 (non-cumulative), respectively. For all-cause mortality, cumulative exposure to PM2.5 for lag-day 0–7 (1.07, 95% CI 1.00, 1.15) and non-cumulative exposure to NO2 at lag-day 6 (1.02, 95% CI 1.00, 1.03) were significant. Exposure to PM10 (per 10 μg/m3) was significantly associated with respiratory mortality at several lag-days. Adjusting for Ramadan did not significantly affect the results. PM10 had significant associations with respiratory mortality of people > 65 years old, and men for several lag-days. For IHD, NO2 affected older people, and men and women over different lag-days. Results of multi-pollutant models were similar to the single-pollutant model outcomes. In conclusion, NO2 and PM10 had more significant relationships with adverse health outcomes than the other pollutants.

Poor Air Quality and Its Association with Mortality in Ho Chi Minh City: Case Study

Along with its rapid urban development, Ho Chi Minh City (HCMC) in recent years has suffered a high concentration of air pollutants, especially fine particulate matters or PM2.5. A comprehensive study is required to evaluate the air quality conditions and their health impact in this city. Given the lack of adequate air quality monitoring data over a large area of the size of HCMC, an air quality modeling methodology is adopted to address the requirement. Here, by utilizing a corresponding emission inventory in combination with The Air Pollution Model-Chemical Transport Model (TAPM-CTM), the predicted concentration of air pollutants is first obtained for PM2.5, NOx, and SO2. Then by associating the pollutants exposed with the mortality rate from three causes, namely Ischemic Heart Disease (IHD), cardiopulmonary, and lung cancer, the impact of air pollution on human health is obtained for this purpose. Spatial distribution has shown a high amount of pollutants concentrated in the central city with a high density of combustion vehicles (motorcycles and automobiles). In addition, a significant amount of emissions can be observed from stevedoring and harbor activities, including ferries and cargo handling equipment located along the river. Other sources such as household activities also contribute to an even distribution of emission across the city. The results of air quality modeling showed that the annual average concentrations of NO2 were higher than the standard of Vietnam National Technical Regulation on Ambient Air Quality (QCVN 05: 2013 40 µg/m3) and World Health Organization (WHO) (40 µg/m3). The annual average concentrations of PM2.5 were 23 µg/m3 and were also much higher than the WHO (10 µg/m3) standard by about 2.3 times. In terms of public health impacts, PM2.5 was found to be responsible for about 1136 deaths, while the number of mortalities from exposure to NO2 and SO2 was 172 and 89 deaths, respectively. These figures demand some stringent measures from the authorities to potentially remedy the alarming situation of air pollution in HCM City.

Assessing NO2-related health effects by non-linear and linear methods on a national level

Exposure to NO2 pollution has a significant adverse effect on residents' health. However, few studies have assessed the health effects associated with NO2 pollution. Compared with PM2.5 pollution, the harmfulness of NO2 pollution has not been quantitatively studied or clearly identified. In this study, we assessed the NO2 exposure-related health effects by non-linear and linear methods, taking advantage of online monitoring and survey data. We also assessed the economic cost of NO2 pollution in 338 cities in China. Our results showed that the average annual concentration of NO2 in the top fifteen cities with more than ten million permanent residents (except for Shenzhen, in the Guangdong province) exceeded the annual Grade II standards (40 μg/m3). The estimated national NO2-related all-cause mortality for non-linear and linear methods were 388.5 × 103 (95% CI: 198.1 × 103–748.2 × 103) and 374.1 × 103 (95% CI: 194.3 × 103–695.9 × 103), respectively. The total calculated national economic cost was about 28.8 billion US$ (95% CI: 14.7–55.4) in 2016. In addition, the comparison results showed that the harm caused by PM2.5 pollution was about four times that of NO2 pollution. Our statistics contribute to the limited research on NO2 pollution's effects on health and the economy in China.

Significant concurrent decrease in PM2.5 and NO2 concentrations in China during COVID-19 epidemic

The strict control measures and social lockdowns initiated to combat COVID-19 epidemic have had a notable impact on air pollutant concentrations. According to observation data obtained from the China National Environmental Monitoring Center, compared to levels in 2019, the average concentration of NO2 in early 2020 during COVID-19 epidemic has decreased by 53%, 50%, and 30% in Wuhan city, Hubei Province (Wuhan excluded), and China (Hubei excluded), respectively. Simultaneously, PM2.5 concentration has decreased by 35%, 29%, and 19% in Wuhan, Hubei (Wuhan excluded), and China (Hubei excluded), respectively. Less significant declines have also been found for SO2 and CO concentrations. We also analyzed the temporal variation and spatial distribution of air pollutant concentrations in China during COVID-19 epidemic. The decreases in PM2.5 and NO2 concentrations showed relatively consistent temporal variation and spatial distribution. These results support control of NOx to further reduce PM2.5 pollution in China. The concurrent decrease in NOx and PM2.5 concentrations resulted in an increase of O3 concentrations across China during COVID-19 epidemic, indicating that coordinated control of other pollutants is needed.

Long-term exposure to nitrogen dioxide and natural-cause and cause-specific mortality in Japan

BackgroundLong-term exposure to air pollution is linked with increased risk of adverse health outcomes, but the evidence for the association between nitrogen dioxide (NO2) and mortality is weak because of the inadequate adjustment of potential confounders and limited spatial resolution of the exposure assessment. Moreover, there are concerns about the independent effects of NO2. Therefore, we examined the association between NO2 long-term exposure and all-cause and cause-specific mortality. MethodsWe included participants who were enrolled in health checkups in Okayama City, Japan, in 2006 or 2007 and were followed until 2016. We used a land-use regression model to estimate the average NO2 concentrations from 2006 to 2007 and allocated them to the participants. We estimated hazard ratios (HRs) for a 10-μg/m3 increase in NO2 levels for all-cause or cause-specific mortality using Cox proportional hazard models. ResultsAfter excluding the participants who were assigned with outlier exposures, a total of 73,970 participants were included in the analyses. NO2 exposure was associated with increased risk of mortality and the HRs and their confidence intervals were 1.06 (95% CI: 1.02, 1.11) for all-cause, 1.02 (0.96, 1.09) for cardiopulmonary, and 1.36 (1.14, 1.63) for lung cancer mortality. However, the elevated risks became equivocal after the adjustment for fine particulate matter except lung cancer. ConclusionLong-term exposure to NO2 was associated with increased risk of all-cause, cardiopulmonary, and lung cancer mortality. The elevated risk for lung cancer was still observable even after adjustment for fine particulate matter.

Differentiation Between Nitrate Aerosol Formation Pathways in a Southeast Chinese City by Dual Isotope and Modeling Studies

AbstractNitrate (NO3−), one of the most important inorganic aerosols in the atmosphere, is mainly formed by oxidation of NOx by the hydroxyl radical (OH) and ozone (O3) in urban atmospheres. However, the fractional contributions of its various oxidation pathways remain unclear. Here, we collected particulate matter with aerodynamic diameter less than 2.5 μm (PM2.5) samples in a second‐tier city in southeast China from 1 September to 31 December 2017 and measured the NO3− and nitrate isotopic compositions (δ15N and δ18O). The average concentration of NO3−, δ15N, and δ18O values were 14.7 ± 11.6 μg/m3, (+4.3 ± 4.3)‰, and (+71.8 ± 14.7)‰ with the ranges from 0.8 to 57.7 μg/m3, −10.5‰ to +12.5‰ and +34.5‰ to +91.9‰, respectively. All three species were significantly higher in winter than in summer. Based on a Bayesian mixing model with a dual isotope array for NO3−, contributions of (37.1 ± 33.4)%, (60.3 ± 32.2)%, and (2.6 ± 2.7)% to NO3− could be attributed to OH oxidation, N2O5 hydrolysis, and NO3 + hydrocarbon (HC) pathways, respectively. Higher OH radical concentrations with higher ratios of OH to O3 led to lower NO3− concentrations, while lower OH radical concentrations with higher ratios of O3 to OH led to higher contributions of N2O5 hydrolysis, forming higher NO3− concentrations in winter. Under low OH, an increased O3 to NOx ratio increased the contribution of the NO3 + HC pathway. The comprehensive analysis of the isotopic compositions of nitrate helped identify the importance of major oxidation pathways of NOx in this city.