A numerical study of contributions to air pollution in Beijing during CAREBeijing-2006

Abstract. An online air pollutant tagged module has been developed in the Nested Air Quality Prediction Model System (NAQPMS) to investigate the impact of local and regional sources on the air pollutants in Beijing during the Campaign of Air Quality Research in Beijing 2006 (CAREBeijing-2006). The NAQPMS model shows high performance in simulating sulfur dioxide (SO2), particulate matter (PM10), nitrogen dioxide (NO2), and ozone (O3) with overall better agreements with the observations at urban sites than rural areas. With the tagged module, the air pollutant contributions from local and regional sources to the surface layer (about 30 m) and the upper layer (about 1.1 km) in Beijing are differentiated and estimated. The air pollutants at the surface layer in Beijing are dominated by the contributions from local sources, accounting for 65 % of SO2, 75 % of PM10 and nearly 90 % of NO2, respectively, comparatively, the 1.1 km layer has large source contributions from the surrounding regions (e.g., southern Beijing), accounting for more than 50 % of the SO2 and PM10 concentrations. County scale analysis is also performed and the results suggest that Tianjin is the dominant source of SO2 in Pinggu County, and Langfang, Hebei is the most important regional contributor to PM10 in Beijing. Moreover, the surrounding regions show larger impact on SO2, PM10 and NO2 in the eastern counties of Beijing (e.g., Pinggu, Tongzhou and Daxing) than those in western Beijing, which is likely due to the Beijing's semi-basin topography and the summer monsoon. Our results indicate that the efforts to control the air pollutants in Beijing should focus on controlling both local and regional emissions.

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A numerical study of the contribution to the air pollutant in Beijing during CAREBeijing-2006

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-5271-2011 ◽

2011 ◽

Vol 11 (2) ◽

pp. 5271-5312 ◽

Cited By ~ 2

Author(s):

Q. Z. Wu ◽

Z. F. Wang ◽

A. Gbaguidi ◽

C. Gao ◽

L. N. Li ◽

...

Keyword(s):

Surface Layer ◽

Air Quality ◽

Rural Areas ◽

Air Pollutants ◽

High Performance ◽

Numerical Study ◽

Air Pollutant ◽

Air Quality Prediction ◽

Regional Sources ◽

The Impact

Abstract. An online air pollutant tagged module has been developed in the Nested Air Quality Prediction Model System (NAQPMS) to investigate the impact of local and regional sources on the air pollutants in Beijing during the Campaign of Air Quality Research in Beijing 2006 (CAREBeijing-2006). The NAQPMS model shows high performance in simulating sulfur dioxide (SO2), particulate matter (PM10), nitrogen dioxide (NO2), and ozone (O3) with overall better agreements with the observations at urban sites than rural areas. With the tagged module, the air pollutant contributions from local and regional sources to the surface layer (about 30 m) and the upper layer (about 1.1 km) in Beijing are differentiated and estimated. The air pollutants at the surface layer in Beijing are dominated by the contributions from local sources, accounting for 65% of SO2, 75% of PM10 and nearly 90% of NO2, respectively, comparatively, the upper layer has large source contributions from the surrounding regions (e.g., southern Beijing), accounting for more than 50% of the SO2 and PM10 concentrations. Country scale analysis is also performed and the results suggest that Tianjin is the dominant source of SO2 in Pinggu County, and Langfang, Hebei is the most important regional contributor to PM10 in Beijing. Moreover, the surrounding regions show larger impact on SO2, PM10 and NO2 in the eastern counties of Beijing (e.g., Pinggu, Tongzhou and Daxing) than those in western Beijing, which is likely due to the Beijing's semi-basin topography and the summer monsoon. Our results indicate that the efforts to control the air pollutants in Beijing should focus on controlling both local and regional emissions.

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FRI0531 AIR POLLUTANTS AND DEVELOPMENT OF INTERSTITIAL LUNG DISEASE IN PATIENTS WITH AUTOIMMUNE DISEASES

Annals of the Rheumatic Diseases ◽

10.1136/annrheumdis-2020-eular.204 ◽

2020 ◽

Vol 79 (Suppl 1) ◽

pp. 865.1-865

Author(s):

H. H. Chen ◽

W. C. Chao ◽

Y. H. Chen ◽

D. Y. Chen ◽

C. H. Lin

Keyword(s):

Air Quality ◽

Autoimmune Diseases ◽

Air Pollutants ◽

Air Pollutant ◽

Air Quality Monitoring ◽

Newly Diagnosed ◽

Science Technology ◽

Air Quality Monitoring Stations ◽

The Impact ◽

Modest Level

Background:Interstitial lung disease (ILD) is characterized by progressive inflammation and fibrosis, and accumulating evidence have shown that exposure to air pollutants was associated with the development of ILD. Autoimmune diseases are highly correlated with ILD, including connective tissue disease-associated ILD (CTD-ILD) as well as interstitial pneumonia with autoimmune features (IPAF), and the development of ILD is a crucial cause of morbidity and mortality in patients with autoimmune diseases. One recent Taiwanese study reported that exposure to air pollutants was associated with incident systemic lupus erythematosus (SLE). However, the impact of air pollutants on the development of ILD among patients with autoimmune diseases remains unknown.Objectives:The study aimed to address the impact of accumulating exposure to air pollutant above moderate level, defined by Air Quality Index (AQI) value higher than 50, on the development of ILD in patients with autoimmune diseases including SLE, rheumatoid arthritis (RA) and primary Sjögren’s syndrome (SS).Methods:We used a National Health Insurance Research Database in Taiwan to enroll patients with SLE (International Classification of Diseases (ICD)-9 code 710.0, n=13,211), RA (ICD-9 code 714.0 and 714.30–714.33, n=32,373), and primary SS (ICD-9 code, 710.0, n=15,246) between 2001 and 2013. We identified newly diagnosed ILD cases (ICD-code 515) between 2012 and 2013 and selected age, sex, disease duration and index-year matched (1:4) patients as non-ILD controls. The hourly levels of air pollutants one year prior to the index-date were obtained from 60 air quality monitoring stations across Taiwan, and the air pollutants in the present study consisted of particulate matter <2.5 μm in size (PM2.5), particulate matter <10 μm in size (PM10), nitrogen dioxide (NO2), carbon monoxide (CO), sulfur dioxide (SO2) and ozone (O3). We used a spatio-temporal model built by a deep-learning mechanism to estimate levels of air pollutants at 374 residential locations based on data of 3 air quality monitoring stations near the location (8). Notably, we used cumulative exposed hours to air pollutants higher than modest level, defined by AQI criteria, given that daily mean level of air pollutants might possibly underestimate the triggered inflammatory effect by a temporary exposure of high-level air pollutant. A conditional logistic regression was used to determine the association between exposure to air pollutant and the development of ILD, adjusting age, gender, Charlson Comorbidity Index (CCI), urbanization, family income, and medications for autoimmune diseases.Results:A total of 272 patients with newly diagnosed ILD were identified among patients with autoimmune diseases, including 39 with SLE, 135 with RA, and 98 with primary SS. We found that the duration of exposure to PM 2.5 higher than modest level was associated with the risk of ILD development in patients with SS (adjOR 1.07, 95% CI 1.01–1.13), and similar trends were also found in patients with SLE (adjOR 1.03, 95% CI 0.95–1.12) and RA (adjOR 1.03, 95% CI 0.99–1.07). Intriguingly, we observed an inverse correlation between the duration of exposure to O3 and the development of ILD in patients with SS (adjOR 0.83, 95% CI 0.70–0.99); however, the finding was not found in patients with SLE (adjOR 1.13, 95% CI 0.92–1.37) and RA (adjOR 0.98, 95% CI 0.87–1.11).Conclusion:In conclusion, we identified that longer exposure to PM2.5 higher than modest level tended to be associated with the development of ILD in patients with autoimmune diseases, mainly SS.References:[1] Araki T, Putman RK, Hatabu H, Gao W, Dupuis J, Latourelle JC, et al. Development and Progression of Interstitial Lung Abnormalities in the Framingham Heart Study. Am J Respir Crit Care Med 2016;194:1514-1522.[2] Tang KT, Tsuang BJ, Ku KC, Chen YH, Lin CH, Chen DY. Relationship between exposure to air pollutants and development of systemic autoimmune rheumatic diseases: a nationwide population-based case-control study. Ann Rheum Dis 2019;78:1288-1291.Disclosure of Interests:Hsin-Hua Chen: None declared, Wen-Cheng Chao: None declared, Yi-Hsing Chen Grant/research support from: Taiwan Ministry of Science and Technology, Taiwan Department of Health, Taichung Veterans General Hospital, National Yang-Ming University, GSK, Pfizer, BMS., Consultant of: Pfizer, Novartis, Abbvie, Johnson & Johnson, BMS, Roche, Lilly, GSK, Astra& Zeneca, Sanofi, MSD, Guigai, Astellas, Inova Diagnostics, UCB, Agnitio Science Technology, United Biopharma, Thermo Fisher, Gilead., Paid instructor for: Pfizer, Novartis, Johnson & Johnson, Roche, Lilly, Astra& Zeneca, Sanofi, Astellas, Agnitio Science Technology, United Biopharma., Speakers bureau: Pfizer, Novartis, Abbvie, Johnson & Johnson, BMS, Roche, Lilly, GSK, Astra& Zeneca, Sanofi, MSD, Guigai, Astellas, Inova Diagnostics, UCB, Agnitio Science Technology, United Biopharma, Thermo Fisher, Gilead., Der-Yuan Chen: None declared, Ching-Heng Lin: None declared

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Selected air pollutants in urban and rural areas, under the influence of power plants

Acta Innovations ◽

10.32933/actainnovations.29.5 ◽

2018 ◽

pp. 41-52 ◽

Cited By ~ 2

Author(s):

Robert Cichowicz ◽

Artur Stelegowski

Keyword(s):

Air Quality ◽

Rural Areas ◽

Air Pollutants ◽

Power Plants ◽

Ambient Air ◽

So2 Emissions ◽

Large Power ◽

Power Stations ◽

Urban And Rural Areas ◽

The Impact

The operation of large power plants, including power stations, and combined heat and power stations, causes the emission of significant amounts of gaseous pollutants into the environment. As a result, in the urban and agricultural areas occurs a pollution of undesirable gaseous substances, such as nitrogen and sulfur oxides. This is especially dangerous for living organisms, soil and water, because, in combination with water vapor, these pollutants are the cause of acid rain. In addition, nitrogen oxides participate in the formation of ground-level ozone, which affects both human health and the condition of existing vegetation. Therefore, the distribution of air pollutants (NO2, SO2 and O3) in the selected urban and rural areas, under the influence of power plants, located in the Lodz Voivodeship, in Poland, in Central-Eastern Europe, was analyzed for a 10-year period (2007–2016). As a result, it was possible to evaluate the impact of the entry into force of Directive 2008/50/EC of the European Parliament and of the Council of 21 May 2008 “on ambient air quality and cleaner air for Europe” on the changes in emissions and concentrations of pollutants in selected locations. As a result of the analysis, a significant decrease in the concentration of SO2 (by 75% in the urban area and by 59% in the rural area), and small changes (from - 8% to + 12%) in NO2 and O3 concentrations in ambient air were found. This indicates the effectiveness of actions aimed at reducing SO2 emissions, however the influence of the power plants on the concentration of air pollutants in these areas is not clear. At the same time, considering the criterion of permissible concentration of ozone and nitrogen dioxide, although the air quality did not improve, the air quality index can be considered as being in the category of "good".

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IMPACT OF URBAN LAND USES AND ACTIVITES ON THE AMBIENT AIR QUALITY IN KLANG VALLEY, MALAYSIA FROM 2014 TO 2020

PLANNING MALAYSIA JOURNAL ◽

10.21837/pm.v18i14.829 ◽

2020 ◽

Vol 18 (14) ◽

Author(s):

Oliver Hoon Leh Ling ◽

Marlyana Azyyati Marzukhi ◽

Jie Kwong Qi ◽

Nurul Ashikin Mabahwi

Keyword(s):

Air Quality ◽

Urban Areas ◽

Air Pollutants ◽

Ambient Air ◽

Air Pollutant ◽

Land Uses ◽

Ambient Air Quality ◽

Residential Areas ◽

Klang Valley ◽

The Impact

Ambient air in the urban area normally is more polluted than less developed areas. This is due to the concentration of urban activities, such as industrial, transportations and commercial or business activities. A study about the impact of urban land uses and activities on the levels of air pollutants in Malaysia’s most urbanised and most developed region that is Klang Valley was conducted. Data of Air Pollutant Index (API) and average concentration of selected air pollutants were used to analyse the ambient air quality of the selected five (5) cities or towns in Klang Valley. The air quality condition of the five (5) cities or towns were related to the land use distributions of the cities or towns with a purpose to understand the impact of land uses on the ambient air quality. Furthermore, the changes of ambient air quality before and after Movement Control Order (MCO) were analysed to examine the impact of human activity changes on the ambient air quality. The study found that a city or a town with more industrial and transportation land uses with fewer greens was more polluted than the area with less industrial and transportation land uses with more greens. However, this finding did not apply to all areas due to effect of winds on the distribution of air pollutants. Besides that, because of MCO, most people stayed at home with the mode of “work from home” that caused air pollutant levels in urban areas to decrease due to less urban activities. Nevertheless, there was a risk of an increase in air pollution levels in residential areas due to the concentration of activities, especially driving motor vehicles in residential areas. A recommendation is given to encourage “work from home” and reduce dependency on auto-mobile in residential areas in order to improve the air quality in urban areas.

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Quantifying Air Pollutant Variations during COVID-19 Lockdown in a Capital City in Northwest China

Atmosphere ◽

10.3390/atmos12060788 ◽

2021 ◽

Vol 12 (6) ◽

pp. 788

Author(s):

Rong Feng ◽

Hongmei Xu ◽

Zexuan Wang ◽

Yunxuan Gu ◽

Zhe Liu ◽

...

Keyword(s):

Air Pollution ◽

Air Quality ◽

Rural Areas ◽

Vehicle Emissions ◽

Motor Vehicle ◽

Northwest China ◽

Air Pollutant ◽

Capital City ◽

Air Pollution Control ◽

Motor Vehicle Emissions

In the context of the outbreak of coronavirus disease 2019 (COVID-19), strict lockdown policies were implemented to control nonessential human activities in Xi’an, northwest China, which greatly limited the spread of the pandemic and affected air quality. Compared with pre-lockdown, the air quality index and concentrations of PM2.5, PM10, SO2, and CO during the lockdown reduced, but the reductions were not very significant. NO2 levels exhibited the largest decrease (52%) during lockdown, owing to the remarkable decreased motor vehicle emissions. The highest K+ and lowest Ca2+ concentrations in PM2.5 samples could be attributed to the increase in household biomass fuel consumption in suburbs and rural areas around Xi’an and the decrease in human physical activities in Xi’an (e.g., human travel, vehicle emissions, construction activities), respectively, during the lockdown period. Secondary chemical reactions in the atmosphere increased in the lockdown period, as evidenced by the increased O3 level (increased by 160%) and OC/EC ratios in PM2.5 (increased by 26%), compared with pre-lockdown levels. The results, based on a natural experiment in this study, can be used as a reference for studying the formation and source of air pollution in Xi’an and provide evidence for establishing future long-term air pollution control policies.

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Gender Differences in Association between Air Pollution and Daily Mortality in the Capital of the Green Lungs of Poland–Population-Based Study with 2,953,000 Person-Years of Follow-Up

Journal of Clinical Medicine ◽

10.3390/jcm9082351 ◽

2020 ◽

Vol 9 (8) ◽

pp. 2351

Author(s):

Łukasz Kuźma ◽

Krzysztof Struniawski ◽

Szymon Pogorzelski ◽

Hanna Bachórzewska-Gajewska ◽

Sławomir Dobrzycki

Keyword(s):

Public Health ◽

Gender Differences ◽

Air Pollution ◽

Air Quality ◽

Air Pollutant ◽

World Health ◽

The European Union ◽

Daily Mortality ◽

Male Population ◽

The Impact

(1) Introduction: air pollution is considered to be one of the main risk factors for public health. According to the European Environment Agency (EEA), air pollution contributes to the premature deaths of approximately 500,000 citizens of the European Union (EU), including almost 5000 inhabitants of Poland every year. (2) Purpose: to assess the gender differences in the impact of air pollution on the mortality in the population of the city of Bialystok—the capital of the Green Lungs of Poland. (3) Materials and Methods: based on the data from the Central Statistical Office, the number—and causes of death—of Białystok residents in the period 2008–2017 were analyzed. The study utilized the data recorded by the Provincial Inspectorate for Environmental Protection station and the Institute of Meteorology and Water Management during the analysis period. Time series regression with Poisson distribution was used in statistical analysis. (4) Results: A total of 34,005 deaths had been recorded, in which women accounted for 47.5%. The proportion of cardiovascular-related deaths was 48% (n = 16,370). An increase of SO2 concentration by 1-µg/m3 (relative risk (RR) 1.07, 95% confidence interval (CI) 1.02–1.12; p = 0.005) and a 10 °C decrease of temperature (RR 1.03, 95% CI 1.01–1.05; p = 0.005) were related to an increase in the number of daily deaths. No gender differences in the impact of air pollution on mortality were observed. In the analysis of the subgroup of cardiovascular deaths, the main pollutant that was found to have an effect on daily mortality was particulate matter with a diameter of 2.5 μm or less (PM2.5); the RR for 10-µg/m3 increase of PM2.5 was 1.07 (95% CI 1.02–1.12; p = 0.01), and this effect was noted only in the male population. (5) Conclusions: air quality and atmospheric conditions had an impact on the mortality of Bialystok residents. The main air pollutant that influenced the mortality rate was SO2, and there were no gender differences in the impact of this pollutant. In the male population, an increased exposure to PM2.5 concentration was associated with significantly higher cardiovascular mortality. These findings suggest that improving air quality, in particular, even with lower SO2 levels than currently allowed by the World Health Organization (WHO) guidelines, may benefit public health. Further studies on this topic are needed, but our results bring questions whether the recommendations concerning acceptable concentrations of air pollutants should be stricter, or is there a safe concentration of SO2 in the air at all.

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To what extent does the environmental magnetism technique acts as a way of assessing the uptake of atmospheric particles by plants?

10.5194/egusphere-egu21-8263 ◽

2021 ◽

Author(s):

Sarah Letaïef ◽

Pierre Camps ◽

Thierry Poidras ◽

Patrick Nicol ◽

Delphine Bosch ◽

...

Keyword(s):

Air Quality ◽

Endemic Species ◽

Fine Particles ◽

Magnetic Measurements ◽

Deposition Velocity ◽

Environmental Magnetism ◽

Air Pollutant ◽

Atmospheric Pollutants ◽

Area Index ◽

The Impact

Numerous studies have already shown the possibility of tracing the sources, the compositions, and the concentration of atmospheric pollutants deposited on plant leaves. In environmental geochemistry, inter-element and isotope ratios from chemical element assays have been used for these purposes. Alternatively, environmental magnetism represents a quick and inexpensive asset that is increasingly used as a relative indicator for concentrations of air pollutant on bio accumulator surfaces such as plants. However, a fundamental issue is still pending: Do plants in urban areas represent a sink for fine particles that is sufficiently effective to improve air quality? This is a very topical issue because some studies have shown that the foliage can trap fine particles by different dry deposition processes, while other studies based on CFD models indicate that plant hedges in cities can hinder the atmospheric dispersion of pollutants and therefore increase pollution at the level of emission sources such as traffic. To date, no consensus was made because several factors not necessary well known must be taken into account, such as, PM concentration and size, prevailing wind, surface structures, epicuticular wax, to mention just a few examples. A first step toward the understanding of the impact of urban greens on air quality is the precise determination of the deposition velocity (Vd) parameter. This latter is specific for each species and it is most of the time underestimated in modeling-based studies by taking standard values. In that perspective, we built a wind tunnel (6 m long, 86 cm wide and 86 cm high) to perform analogical experiments on different endemic species. All parameters are controlled, i.e, the wind speed, the nature and the injection time of pollutants (Gasoline or Diesel exhausts, brakes or tires dust, etc&#8230;). We can provide the PM concentrations upwind and downwind of natural reconstituted hedges by two dustmeters (LOACs - M&#233;t&#233;oModem). Beforehand, parameters such as the hedge resistance (%) or the leaf area index (LAI) have been estimated for each studied specie to allow comparability between plants removal potential. The interest would ultimately combine PM concentration measured by size bins from the LOACs with magnetic measurements (ARM, IRM100mT, IRM300mT and SIRM) of plant leaves. The idea is to check whether it would be possible to precisely determine in situ the dust removal rate by urban greens with environmental magnetism measurements. Up to now, we have carried out on different endemic species such as Elaeagnus x ebbingei leaves and Mediterranean pine needles, the results of which will be presented.

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Avoided Mortality Associated with Improved Air Quality from an Increase in Renewable Energy in the Spanish Transport Sector: Use of Biofuels and the Adoption of the Electric Car

Atmosphere ◽

10.3390/atmos12121603 ◽

2021 ◽

Vol 12 (12) ◽

pp. 1603

Author(s):

Ana R. Gamarra ◽

Yolanda Lechón ◽

Marta G. Vivanco ◽

Mark Richard Theobald ◽

Carmen Lago ◽

...

Keyword(s):

Air Quality ◽

Health Impact ◽

Air Pollutant ◽

Transport Sector ◽

Population Exposure ◽

Baseline Scenario ◽

Premature Deaths ◽

Electric Car ◽

The Impact

This paper assesses the health impact, in terms of the reduction of premature deaths associated with changes in air pollutant exposure, resulting from double-aim strategies for reducing emissions of greenhouse gases and air pollutants from the transport sector for the year 2030 in Spain. The impact on air quality of selected measures for reducing emissions from the transport sector (increased penetration of biofuel and electric car use) was assessed by air quality modeling. The estimation of population exposure to NO2, particulate matter (PM) and O3 allows for estimation of associated mortality and external costs in comparison with the baseline scenario with no measures. The results show that the penetration of the electric vehicle provided the largest benefits, even when the emissions due to the additional electricity demand were considered.

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Impact of COVID-19 Lockdown and Atmospheric Circulation on the Air Quality in Wuhan During Early 2020

E3S Web of Conferences ◽

10.1051/e3sconf/202129902011 ◽

2021 ◽

Vol 299 ◽

pp. 02011

Author(s):

Youyong Xie ◽

Xiefei Zhi

Keyword(s):

Air Quality ◽

Atmospheric Circulation ◽

Air Pollutants ◽

General Circulation ◽

Circulation Pattern ◽

Atmospheric Circulation Patterns ◽

Atmospheric General Circulation ◽

Circulation Patterns ◽

The Impact

Previous studies indicated that the air quality was improved in Wuhan during COVID-19 lockdown. However, the impact of atmospheric general circulation on the changes of air quality has not been taken into account. The present study aims to discuss the improvement of air quality in Wuhan and its possible reasons during COVID-19 lockdown. The results showed that all air pollutants except O3 decreased in Wuhan during early 2020. The occurrence days of A, C, W and NW types’ circulation pattern during early 2020 are more than those during the same period of 1979-2020. The occurrence days of SW type’s circulation pattern is slightly less than those during early 1979-2020. With more occurrence days of these dominant atmospheric circulation patterns, the number of polluted days could rise in Wuhan during early 2020. Nevertheless, this scenario didn’t occur. The COVID-19 lockdown did improve the air quality in Wuhan during early 2020.

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Mobile monitoring of urban air quality at high spatial resolution by low-cost sensors: Impacts of COVID-19 pandemic lockdown

10.5194/acp-2020-1169 ◽

2020 ◽

Author(s):

Shibao Wang ◽

Yun Ma ◽

Zhongrui Wang ◽

Lei Wang ◽

Xuguang Chi ◽

...

Keyword(s):

Air Quality ◽

Air Pollutants ◽

Low Cost ◽

Air Pollutant ◽

Mitigation Strategies ◽

Traffic Emissions ◽

Urban Air ◽

Industrial Emissions ◽

Gis Technology ◽

Mobile Monitoring

Abstract. The development of low-cost sensors and novel calibration algorithms provides new hints to complement conventional ground-based observation sites to evaluate the spatial and temporal distribution of pollutants on hyper-local scales (tens of meters). Here we use sensors deployed on a taxi fleet to explore the air quality in the road network of Nanjing over the course of a year (Oct. 2019–Sep. 2020). Based on GIS technology, we develop a grid analysis method to obtain 50 m resolution maps of major air pollutants (CO, NO2, and O3). Through hotspots identification analysis, we find three main sources of air pollutants including traffic, industrial emissions, and cooking fumes. We find that CO and NO2 concentrations show a pattern: highways > arterial roads > secondary roads > branch roads > residential streets, reflecting traffic volume. While the O3 concentrations in these five road types are in opposite order due to the titration effect of NOx. Combined the mobile measurements and the stationary station data, we diagnose that the contribution of traffic-related emissions to CO and NO2 are 42.6 % and 26.3 %, respectively. Compared to the pre-COVID period, the concentrations of CO and NO2 during COVID-lockdown period decreased for 44.9 % and 47.1 %, respectively, and the contribution of traffic-related emissions to them both decreased by more than 50 %. With the end of the COVID-lockdown period, traffic emissions and air pollutant concentrations rebounded substantially, indicating that traffic emissions have a crucial impact on the variation of air pollutants levels in urban regions. This research demonstrates the sense power of mobile monitoring for urban air pollution, which provides detailed information for source attribution, accurate traceability, and potential mitigation strategies at urban micro-scale.

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