Air Quality Regions Research Articles

Ozone response modeling to NOx and VOC emissions: Examining machine learning models

Current machine learning (ML) applications in atmospheric science focus on forecasting and bias correction for numerical modeling estimations, but few studies examined the nonlinear response of their predictions to precursor emissions. This study uses ground-level maximum daily 8-hour ozone average (MDA8 O3) as an example to examine O3 responses to local anthropogenic NOx and VOC emissions in Taiwan by Response Surface Modeling (RSM). Three different datasets for RSM were examined, including the Community Multiscale Air Quality (CMAQ) model data, ML-measurement-model fusion (ML-MMF) data, and ML data, which respectively represent direct numerical model predictions, numerical predictions adjusted by observations and other auxiliary data, and ML predictions based on observations and other auxiliary data.The results show that both ML-MMF (r = 0.93–0.94) and ML predictions (r = 0.89–0.94) present significantly improved performance in the benchmark case compared with CMAQ predictions (r = 0.41–0.80). While ML-MMF isopleths exhibit O3 nonlinearity close to actual responses due to their numerical base and observation-based correction, ML isopleths present biased predictions concerning their different controlled ranges of O3 and distorted O3 responses to NOx and VOC emission ratios compared with ML-MMF isopleths, which implies that using data without support from CMAQ modeling to predict the air quality could mislead the controlled targets and future trends. Meanwhile, the observation-corrected ML-MMF isopleths also emphasize the impact of transboundary pollution from mainland China on the regional O3 sensitivity to local NOx and VOC emissions, which transboundary NOx would make all air quality regions in April more sensitive to local VOC emissions and limit the potential effort by reducing local emissions.Future ML applications in atmospheric science like forecasting or bias correction should provide interpretability and explainability, except for meeting statistical performance and providing variable importance. Assessment with interpretable physical and chemical mechanisms and constructing a statistically robust ML model should be equally important.

Haze Pollution in the Unstable Atmospheric Boundary Layer Over the West Bank of Taiwan Strait Induced by Regional Transport of PM2.5

AbstractThis study investigated the regional transport of particulate matter (PM2.5) leading to air pollution in Fuzhou, in the west bank of the Taiwan Strait (WBTS), which has a relatively good air quality with a lower aerosol optical depth than that of East China. The continental polluted aerosol zone over the coast of East China was identified as an aerosol transport belt, and the daily aerosol dynamics observed by MODIS remote sensing indicated the southward transport of fine particulate matter to the WBTS along the coast. The external air pollutants from regional transport contributed 84% of the PM2.5 detected in Fuzhou, while only 16% due to local emissions of air pollutants. The northerly winds of the cold front drove the southward transport of polluted air masses along the coast of the northwest Pacific from the Yangtze River Delta (YRD) to the WBTS. The vertical mixing of air pollutants from the upper boundary layer to the surface layer could be conducive to regional‐transport‐induced haze pollution in this coastal area of the WBTS. Fuzhou is considered a receptor region of PM2.5 transport in Eastern China, and the source region is mainly from the YRD. The results of this study have significant implications on determining the source of pollution and controlling local air quality for good air quality regions. This study also shed some light on using multi‐satellites to fill the surface observation gaps in coast or nearshore areas, and to confirm the characteristics and passways of aerosol transport.

Air Quality, Pollution and Sustainability Trends in South Asia: A Population-Based Study.

Introduction: Worsening air quality and pollution lead to numerous environmental health and sustainability issues in the South Asia region. This study analyzes India, Nepal, Bangladesh, Pakistan, Sri Lanka, and Nepal for air quality data trends and sustainability indicators. Methodology: By using a population-based study design, six South Asian countries were analyzed using a step-wise approach. Data were obtained from government websites and publicly available repositories for region dynamics and key variables. Results: Between 1990 and 2020, air quality data indicated the highest rise in CO2 emissions in India (578.5 to 2441.8 million tons) (MT), Bangladesh, Nepal, and Pakistan. Greenhouse gas emissions, from 1990 to 2018, nearly tripled in India (1990.4 to 3346.6 MT of CO2-equivalents), Nepal (20.6 to 54.6 MT of CO2-equivalents), and Pakistan, and doubled in Bangladesh. Methane emissions rose the highest in Pakistan (70.4 to 151 MT of CO2-equivalents), followed by Nepal (17 to 31 MT of CO2-equivalents) and India (524.8 to 669.3 MT of CO2-equivalents). Nitrous oxide nearly doubled in Bangladesh (16.5 to 29.3 MT of CO2-equivalents), India (141.6 to 256.9 MT of CO2-equivalents), Nepal (17 to 31 MT of CO2-equivalents), and more than doubled in Pakistan (27 to 61 MT of CO2-equivalents). On noting particulate matter 2,5 annual exposure, India saw the highest rise from 81.3 µg/m3 (in 1990) to 90.9 µg/m3 (2017), whereas trends were steady in Pakistan (60.34 to 58.3 µg/m3). The highest rise was noted in Nepal (87.6 to 99.7 µg/m3) until 2017. During the coronavirus disease 19 pandemic, the pre-and post-pandemic changes between 2018 and 2021 indicated the highest PM2.5 concentration in Bangladesh (76.9 µg/m3), followed by Pakistan (66.8 µg/m3), India (58.1 µg/m3), Nepal (46 µg/m3) and Sri Lanka (17.4 µg/m3). Overall, South Asian countries contribute to the worst air quality and sustainability trends regions worldwide. Conclusions: Air pollution is prevalent across a majority of South Asia countries. Owing to unsustainable industrial practices, pollution trends have risen to hazardous levels. Economic, environmental, and human health impacts have manifested and require urgent, concerted efforts by governing bodies in the region.

Spatiotemporal patterns of polychlorinated dibenzo-p-dioxins and dibenzofurans and dioxin-like polychlorinated biphenyls in foodstuffs in air quality regions in Taiwan.

High-fat food intake is the main source of dioxin-like compounds for humans, such as consumption of meat, dairy and eggs, and seafood products. Fruits, vegetables, and cereals have relatively low levels of dioxin-like compounds, but because of high consumption they also contribute to the food-borne intake. It is necessary to clarify dietary dioxin exposure affected by different food contamination levels and dietary habits among different geographic areas. We aimed to evaluate chronic dietary PCDD/Fs and DL-PCBs exposure in 725 individual foods in 14 categories in 6 Taiwan air quality regions (AQRs) and a total of 2441 foods from 2004 to 2018. We estimated daily PCDD/Fs + DL-PCBs intake on the basis of sex- and age-specific foodstuff ingestion rate and PCDD/Fs+ DL-PCBs concentrations using a probabilistic approach. PCDD/F+ DL-PCB levels among the different sampling periods exhibited a decreasing trend in fish and aquatic products (from 0.384 ± 0.764 to 0.206±0.223pgWHO05-TEQg−1 w.w.) (p for trend=0.043), livestock products (from 0.133±0.298 to 0.035±0.043 pgWHO05-TEQ g−1 w.w.), eggs (from 0.221 ± 0.373 to 0.056 ± 0.048 pgWHO05-TEQ g−1 w.w.) (p for trend = 0.002), and dairy samples (from 0.066 ± 0.075 to 0.024 ± 0.026 pgWHO05-TEQ g−1 w.w.) (p for trend= 0.001). All lifetime average daily doses (LADD) were below provisional tolerable monthly intake (PTMI) but higher than the TWI for PCDD/Fs and DL-PCBs in food. The percentages of the contribution of each food group to the total dietary intake of TEQPCDD/F+PCB in different ambient air dispersion areas and age groups. The total daily intake of PCDD/Fs and DL-PCBs by Taiwanese differed between AQRs (0.188–0.397 pgWHO05-TEQ kg−1 b.w. day−1). The observed geographical variations were likely due to differences in food habits, cuisines, culture and levels of environmental contamination among various regions in Taiwan. By sensitivity analysis, we have identified the major contribution to LADD, which was the dioxin levels in marine fish, fresh water fish and fish related products, and followed by dioxin levels in duck eggs. In addition, marine and freshwater fish consumption rate accounts more than 10.2%. These major exposure variables was also consistent with the findings of total daily intake in different AQRs.

Regional Differences of Primary Meteorological Factors Impacting O3 Variability in South Korea

Surface ozone (O3) is a harmful pollutant and effective strategies must be developed for its reduction. In this study, the impact of meteorological factors on the annual O3 variability for South Korea were analyzed. In addition, the regional differences of meteorological factors in six air quality regions in South Korea (Seoul Metropolitan Area, SMA; Central region, CN; Honam, HN; Yeongnam, YN; Gangwon, GW; Jeju, JJ) were compared. The analysis of ground observation data from 2001 to 2017 revealed that the long-term variability of O3 concentration in South Korea continuously increased since 2001, and the upward trend in 2010 to 2017 (Period 2, PRD2) was 29.8% higher than that in 2001 to 2009 (Period 1, PRD1). This was because the meteorological conditions during PRD2 became relatively favorable for high O3 concentrations compared to conditions during PRD1. In particular, the increase in the solar radiation (SR) and maximum temperature (TMAX) and the decrease in the precipitation (PRCP) and wind speed (WS) of South Korea in PRD2 were identified as the main causes for the rise in O3 concentrations. When meteorological factors and O3 variability were compared among the six air quality regions in South Korea during PRD1 and PRD2, significant differences were observed. This indicated that different meteorological changes occurred in South Korea after 2010 due to the different topographical characteristics of each region; thus, O3 variability also changed differently in each region. Interestingly, for the regions with almost similar meteorological changes after 2010, the O3 concentration changed differently depending on the difference in the distribution of emissions. These results indicate that the O3–meteorology relationship shows spatiotemporal differences depending on the topographical and emission distribution characteristics of each area and implies that it is necessary to fully consider such differences for efficient O3 reduction.

Spatiotemporal assessment of mortality attributable to ambient PM2.5 exposure in Taiwan during 2008–2015

In this study, we quantified the spatiotemporal burden of mortality attributable to ambient fine particulate matter (PM2.5, which is defined as a mass of particles with an aerodynamic dry diameter of ≤ 2.5 μm) in Taiwan during 2008–2015. Hourly concentrations of PM2.5 were obtained from the Taiwan Air Quality Monitoring Network. According to geographical and climatic characteristics, the Taiwan Environmental Protection Administration has divided Taiwan into seven air quality regions (AQRs): the North (four districts), Chu-Miao (two districts), Central (three districts), Yun-Chia-Nan (three districts), Kao-Ping (two districts), Yilan (one district), and Hua-Tung (two districts) regions. Demographic information and mortality data were acquired from the Department of Household Registration and National Death Registry of Taiwan, respectively. The World Health Organization’s (WHO) AirQ+ software was used to estimate the mortality attributable to exposure to PM2.5 for specific causes of deaths, specifically from ischemic heart disease (IHD), cerebrovascular disease (stroke), lung cancer (LC), and chronic obstructive pulmonary disease (COPD). The results indicated that nationally, the annual mean concentration of PM2.5 decreased from 2008 (30.75 μg m−3) to 2015 (20.07 μg m−3). Moreover, the population-attributable fraction (PAF) of cause-specific mortality due to PM2.5 exposure for IHD, stroke, LC, and COPD decreased from 21.72%, 30.31%, 15.97%, and 13.04%, respectively, in 2008 to 17.40%, 18.18%, 10.77%, and 9.09%, respectively, in 2015. Geographic variation was observed in the PM2.5 concentration and PAF. High PM2.5 levels and PAF of mortality due to PM2.5 were observed in southwestern and central Taiwan. Moreover, cardiovascular and cerebrovascular disease (IHD and stroke) accounted for the majority of the premature deaths related to PM2.5. Stroke was the largest contributor in PM2.5-related premature mortality; however, IHD instead of stroke became the largest contributor in the Yilan AQR in 2010, 2012, and 2014–2015 and in the Hua-Tung AQR in 2012–2015 with relatively low PM2.5 levels (less than 19 μg m−3). In Taiwan, ambient PM2.5 contributed substantially to the burden of disease. Our results could aid authorities in determining the effectiveness of current air pollution control strategies and plans.

Understanding the Spatial-Temporal Patterns and Influential Factors on Air Quality Index: The Case of North China.

North China has become one of the worst air quality regions in China and the world. Based on the daily air quality index (AQI) monitoring data in 96 cities from 2014–2016, the spatiotemporal patterns of AQI in North China were investigated, then the influence of meteorological and socio-economic factors on AQI was discussed by statistical analysis and ESDA-GWR (exploratory spatial data analysis-geographically weighted regression) model. The principal results are as follows: (1) The average annual AQI from 2014–2016 exceeded or were close to the Grade II standard of Chinese Ambient Air Quality (CAAQ), although the area experiencing heavy pollution decreased. Meanwhile, the positive spatial autocorrelation of AQI was enhanced in the sample period. (2) The occurrence of a distinct seasonal cycle in air pollution which exhibit a sinusoidal pattern of fluctuations and can be described as “heavy winter and light summer.” Although the AQI generally decreased in other seasons, the air pollution intensity increased in winter with the rapid expansion of higher AQI value in the southern of Hebei and Shanxi. (3) The correlation analysis of daily meteorological factors and AQI shows that air quality can be significantly improved when daily precipitation exceeds 10 mm. In addition, except for O3, wind speed has a negative correlation with AQI and major pollutants, which was most significant in winter. Meanwhile, pollutants are transmitted dynamically under the influence of the prevailing wind direction, which can result in the relocation of AQI. (4) According to ESDA-GWR analysis, on an annual scale, car ownership and industrial production are positively correlated with air pollution; whereas increase of wind speed, per capita gross domestic product (GDP), and forest coverage are conducive to reducing pollution. Local coefficients show spatial differences in the effects of different factors on the AQI. Empirical results of this study are helpful for the government departments to formulate regionally differentiated governance policies regarding air pollution.

Optimal vehicle use in the presence of episodic mobile-source air pollution

This paper develops a conceptual model of vehicle trips in a region plagued by weather-dependent, mobile-source air pollution, and numerically estimates optimal trips for one of the nation's perennially worst air quality regions in terms of short-term particulate matter. Based upon data-driven parameters and damage estimates, our numerical model generates optimal values for region-wide vehicle trips and associated PM2.5 concentrations along with their corresponding time paths. Our dataset includes a host of pertinent weather variables that determine PM2.5 concentrations both independently as well as interacted with vehicle trips. As a result, our empirical model enables us to isolate the conditions under which vehicle travel most affects air pollution levels. Our results suggest that maximizing net social welfare in the presence of mobile-source pollution requires substantial reductions in traditional, emissions-generating vehicle usage on days experiencing critical weather conditions – in the case of our study area, temperature inversions. Because they are socially optimal and targeted solely for days with temperature inversions, the estimated reductions in vehicle usage are substantially larger than those proposed by Moscardini and Caplan (2017) to attain the daily National Ambient Air Quality Standard (NAAQS) for particulate matter on an average basis. We find that the optimal reduction in vehicle trips result in corresponding particulate matter concentrations that are roughly 6–13% of the NAAQS.

Seasonal Assessment of Relative Humidity, Ambient Air Temperature and CO2 Concentration Level in School Buildings of Kigali-Rwanda

Numerous researches on air quality have shown that schools settled in poor ambient air quality regions, the later can negatively affect health of people at the school including students, teachers and other staff members. In Kigali city, most of the schools are naturally ventilated given their surroundings, school car-parks, school occupancy and number of people attending school daily. The seasonal assessment of relative humidity, ambient air temperature and co2 concentration levels in school buildings of Kigali was the main objective of this paper. This research was carried out within three schools located in different parts of Kigali city and having dissimilar construction designs. Sampling activities were performed during both dry and rainy seasons by using air visual nodes instruments. Results indicated that the level of ambient air temperature for dry season and rainy season was in the range of (21-27) oC and (18-25) oC respectively for the three schools. The carbon dioxide concentration for the schools was in the range of (350-450) ppm for dry season and (400-550) ppm for rain season. The relative humidity of rainy season was higher than that of dry season. The result values found exceeded the recommended values of World Health Organization guidelines of 18 oC for temperature and 350 ppm for CO2. This paper suggests that school-car-parks and school-kitchens should be remote from schools. Waste-materials at school should be well managed and their disposal should be away from school-location. Schools should be surrounded by trees and gardens for better air quality within schools.

Evaluating Taiwan's air quality variation trends using grey system theory

According to geographical characteristics and air quality conditions, the Taiwan Environmental Protection Agency has divided the island into 7 air quality regions (AQRs) including Northern, Chu‐Miao, Central, Yun‐Chia‐Nan, Kao‐Ping, I‐lan and Hwa‐Tung AQRs. The grey relational grade (GRG) of all AQRs and nationwide grade were calculated to comprehend the level of contamination. Then the grey model GM (0, N) was used to evaluate the effects of 5 primary contaminants on air quality. The results indicated that the ranking of air quality for the 7 AQRs from the best to the worst were as follows: Hwa‐Tung > I‐lan > Chu‐Miao > Northern > Yun‐Chia‐Nan > Central > Kao‐Ping. The 5 most common contaminants from the greatest to the least were as follows: CO > SO2 > NO > O3 > PM10.

San Francisco Bay Area Parking Management Plan

Under the mandate of the 1970 Federal Clean Air Act, the Environmental Protection Agency (EPA) promulgated regulations to improve and maintain the air quality in those Air Quality Regions (AQCR) where the primary national ambient air quality standards were exceeded. There are institutional and political obstacles that stand in the way of parking management regulations. There is no evidence to support the claim that parking related controls would really be effective in reducing the total number of vehicle miles traveled. This situation provides the opportunity to investigate and evaluate the problems, prospects, and processes associated with establishing parking management in the San Francisco Bay Area. The report examines the development of a case study on how the local and regional agencies responded to a Federal transportation regulatory program.

Regional Transport and Transformation of Sulfur Dioxide to Sulfates in the U. S.

The trends in and relationships between ambient air concentrations of sulfur dioxide and sulfate aerosols at 48 urban sites and 27 nonurban sites throughout the U.S. between 1963 and 1972 have been analyzed. The substantial decreases in ambient SO/sub 2/ concentrations measured at urban sites in the eastern and midwestern U.S. are consistent with the corresponding reductions in local SO/sub 2/ emissions, but these decreases have been accompanied by only modest decreases in ambient sulfate concentrations. Large differences in the amounts of SO/sub 2/ emitted within individual air quality control regions are associated with much smaller differences in the corresponding ambient sulfate concentrations. Substantial changes in the patterns of SO/sub 2/ emissions between air quality regions result in essentially no differences between ambient sulfate concentrations in those air quality regions. Comparisons of several air quality regions in the eastern and western U.S. with similar SO/sub 2/ emission levels and patterns of emissions clearly demonstrates the higher ambient sulfate concentration levels in eastern air quality control regions. Relationships between SO/sub 2/, sulfates, and vanadium concentrations at eastern nonurban U.S. sites cannot be explained by local emission sources. These various observed results can be best explained by long distance sulfur oxide transportmore » with chemical conversion of SO/sub 2/ to sulfates occurring over ranges of hundreds of kilometers. This conclusion has been suggested earlier and the present analysis strongly supports previous discussions. An impact of long range transport of sulfates is to emphasize the need for consistent strategies for reduction of sulfur oxides throughout large geographical regions. Additions of large capacities involving elevated sources in mid-continental or western regions could result in significant increases in sulfate concentrations well downwind of such sources.« less

Non-methane hydrocarbon air quality measurements.

It is important in the implementation of the air quality standard for ozone/oxidants and non-methane hydrocarbons to develop quantitative relationships between these pollutants in air quality regions. Analyses for ambient air non-methane hydrocarbon give a direct measure of the progress in control of hydrocarbon emissions and in the reduction of oxidant/ozone concentration levels. Total hydrocarbon concentrations are much more available than non-hydrocarbon levels. An empirical relationship between total hydrocarbons and non-methane hydrocarbons has been obtained from measurements at both west and east coast sites in the U. S. The comparability of measurements from flame ionization analyzers and gas chromatography has been demonstrated. Either analytical technique can be applied to samples collected at monitoring sites to provide the 6-9 A.M. non-methane hydrocarbon aerometric results specified in the air quality standards.