Air pollutant concentrations

About: Air pollutant concentrations is a research topic. Over the lifetime, 1652 publications have been published within this topic receiving 36138 citations.

Persistent pollution episodes, transport pathways, and potential sources of air pollution during the heating season of 2016-2017 in Lanzhou, China.

Abstract: As one of the most important industrial cities in Northwest China, Lanzhou currently suffers from serious air pollution. This study analyzed the formation mechanism and potential source areas of persistent air pollution in Lanzhou during the heating period from November 1, 2016 to March 31, 2017 based on the air pollutant concentrations and relevant meteorological data. Our findings indicate that particulate pollution was extremely severe during the study period. The daily PM2.5 and PM10 concentrations had significantly negative correlations with daily temperature, wind speed, maximum daily boundary layer height, while the daily PM2.5 and PM10 concentrations showed significantly positive correlations with daily relative humidity. Five persistent pollution episodes were identified and classified as either stagnant accumulation or explosive growth types according to the mechanism of pollution formation and evolution. The PM2.5 and PM10 concentrations and PM2.5/PM10 ratio followed a growing "saw-tooth cycle" pattern during the stagnant accumulation type event. Dust storms caused abrupt peaks in PM10 and a sharp decrease in the PM2.5/PM10 ratio in explosive growth type events. The potential sources of PM10 were mainly distributed in the Kumtag Desert in Xinjiang Uygur Autonomous Region, the Qaidam Basin and Hehuang Valley in Qinghai Province, and the western and eastern Hexi Corridor in Gansu Province. The contributions to PM10 were more than 120 μg/m3. The important potential sources of PM2.5 were located in Hehuang Valley in Qinghai and Linxia Hui Autonomous Prefecture in Gansu; the concentrations of PM2.5 were more than 60 μg/m3.

Automotive emissions will be causing a serious pollution problem in near future in Tehran

Abstract: Tehran is facing a serious automotive air pollution problem. This is due to the large number of vehicles operating in Tehran, no auto‐exhaust emission control strategies in effect, and frequent occurrence of traffic congestions. Based on the emission factors which have been experimentally developed for automobiles in Tehran, Traffic survey, and fuel consumptions data the dally tonnage of the air pollutants from vehicles and other sources was calculated for year 1977. The study then focuses on the years 1982 and 1987. For each of these years projections of automotive and stationary emissions of air pollutants were determined under the assumption that no auto‐emission control would be implemented. Those emissions were then adjusted according to the extent of control in use. Results show that automotive emissions of carbon monoxide and unburnt hydrocarbon loom large in the future total emissions picture of Tehran. As a matter of fact, carbon monoxide emissions from automobile will reach 8100 tons pe...

On Impact of Precipitation Intensity of Air Pollutants in Winter and Spring in Chongqing Downtown

Abstract: With the daily average data of precipitation and environmental monitoring in Jan-Mar and NovDec from 2004to 2008in Chongqing downtown,studies have been made on concentration distribution of air pollution and scavenging activity in different levels of precipitation intensity.The results show that,when rainfall is above 5mm,air pollutant concentrations will be clearly reduced,with the decline rate increasing with rainfall,except that the correspondence between them is general.In continuing precipitation days,air pollutant concentrations are reduced significantly in the first and second day,but reduced poorly in the third and fourth day.In the 1-9.9mm range of precipitation intensity,the clearance rate of air pollutants with each additional 1mm is the greatest,in the range of 10-15mm,and clearance rate is almost no increase with each additional 1mm,when precipitation Intensity above 15mm,clearance rate will increase with each additional 1mm.

Associations of Ambient Air Pollutants and Meteorological Factors With COVID-19 Transmission in 31 Chinese Provinces: A Time Series Study.

Abstract: Evidence regarding the effects of environmental factors on COVID-19 transmission is mixed. We aimed to explore the associations of air pollutants and meteorological factors with COVID-19 confirmed cases during the outbreak period throughout China. The number of COVID-19 confirmed cases, air pollutant concentrations, and meteorological factors in China from January 25 to February 29, 2020, (36 days) were extracted from authoritative electronic databases. The associations were estimated for a single-day lag as well as moving averages lag using generalized additive mixed models. Region-specific analyses and meta-analysis were conducted in 5 selected regions from the north to south of China with diverse air pollution levels and weather conditions and sufficient sample size. Nonlinear concentration-response analyses were performed. An increase of each interquartile range in PM2.5, PM10, SO2, NO2, O3, and CO at lag4 corresponded to 1.40 (1.37-1.43), 1.35 (1.32-1.37), 1.01 (1.00-1.02), 1.08 (1.07-1.10), 1.28 (1.27-1.29), and 1.26 (1.24-1.28) ORs of daily new cases, respectively. For 1°C, 1%, and 1 m/s increase in temperature, relative humidity, and wind velocity, the ORs were 0.97 (0.97-0.98), 0.96 (0.96-0.97), and 0.94 (0.92-0.95), respectively. The estimates of PM2.5, PM10, NO2, and all meteorological factors remained significantly after meta-analysis for the five selected regions. The concentration-response relationships showed that higher concentrations of air pollutants and lower meteorological factors were associated with daily new cases increasing. Higher air pollutant concentrations and lower temperature, relative humidity and wind velocity may favor COVID-19 transmission. Controlling ambient air pollution, especially for PM2.5, PM10, NO2, may be an important component of reducing risk of COVID-19 infection. In addition, as winter months are arriving in China, the meteorological factors may play a negative role in prevention. Therefore, it is significant to implement the public health control measures persistently in case another possible pandemic.