Air Quality of Work, Residential, and Traffic Areas during the COVID-19 Lockdown with Insights to Improve Air Quality

This study investigated the concentrations of air pollutants (NO, NO2, NOx, SO2, CO, O3, PM10, and PM2.5) at three sites with different traffic loads (work, residential, and traffic sites) before, during, and after the COVID-19 lockdown. The main objective of this study was to evaluate the effects and associated potential pollution control implications of the lockdown on the quality of ambient air at three selected sites in the urban area of Riyadh City. The average concentrations of NO, NO2, NOx, and CO decreased during the lockdown period by 73%, 44%, 53%, and 32% at the work site; 222%, 85%, 100%, and 60% at the residential site; and 133%, 60%, 101%, and 103% at the traffic site relative to the pre-lockdown period, respectively. The average concentration of O3 increased by 6% at the work site, whereas the concentration of SO2 increased by 27% at the residential site and decreased by 6.5% at the work site. The changes in PM10 and PM2.5 varied and did not exhibit a clear pattern. The air quality index (AQI) results indicated that the contribution to “undesired” air quality by O3 was 35.29% of the lockdown period at the work site while contributions to undesired air quality by PM10 and PM2.5 were 75.6% and 100% at the work site, 94.5% and 100% at the residential site, and 96.7% and 100% at the traffic site, respectively. The findings of this study are useful for devising effective urban pollution abatement policies. Applying control measures comparable to the lockdown measures over one week will result in a decrease of approximately 19% and 15% in CO mean concentration and 25% and 18% in NO2 mean concentration at residential and traffic sites, respectively.

Air Quality of Work, Residential, and Traffic Areas During the COVID-19 Lockdown with Insights to Improve Air Quality

This study investigated the concentrations of air pollutants (NO, NO2, NOx, SO2, CO, O3, PM10, and PM2.5) at three sites with different traffic loads (work, residential, and traffic sites) before, during, and after the COVID-19 lockdown. The main objective of this study was to evaluate the effects and associated potential pollution control implications of the lockdown on the quality of ambient air at three selected sites in the urban area of Riyadh City. The average concentrations of NO, NO2, NOx, and CO decreased during the lockdown period by 73%, 44%, 53%, and 32% at the work site, 222%, 85%, 100%, and 60% at the residential site, and 133%, 60%, 101%, and 103% at the traffic site relative to the pre-lockdown period, respectively. The average concentration of O3 increased by 6% at the work site, whereas the concentration of SO2 increased by 27% at the residential site and decreased by 6.5% at the work site. The changes in PM10 and PM2.5 varied and did not exhibit a clear pattern. The air quality index (AQI) results indicated that the contribution to “undesired” air quality by O3 was 35.29% of the lockdown period at the work site while contributions to undesired air quality by PM10 and PM2.5 were 75.6% and 100% at the work site, 94.5% and 100% at the residential site, and 96.7% and 100% at the traffic site, respectively. The findings of this study are useful for devising effective urban pollution abatement policies. Applying control measures comparable to the lockdown measures over one week will result in a decrease of approximately 19% and 15% in CO mean concentration and 25% and 18% in NO2 mean concentration at residential and traffic sites, respectively. Significant mitigation of urban air pollution could be accomplished through intermittent implementations of strict pollution control measures.

Characteristics of near-surface air pollutants at an urban station in the central Indo-Gangetic Basin

Measurements of near-surface air pollutants at an urban station, Lucknow have been studied at two contrasting sites as residential and industrial during three-year period from 2015 to 2017 to understand their variability on different temporal scales. The annual mean mass concentrations of sulphur dioxide (SO2), nitrogen dioxide (NO2), nitric oxide (NO) and particulate matter of size less than 2.5 µm (PM2.5) at an industrial site were about 10 ± 5, 28 ± 17, 10 ± 11 and 128 ± 99 µg m-3 and at the residential site were about 8 ± 5, 30 ± 21, 9 ± 7 and 102 ± 81 µg m-3 respectively. It was observed that the annual mean mass concentration of PM2.5 was about 3 times higher than its annual National Ambient Air Quality Standards (NAAQS) level. However, SO2 and NO2 were about 5 and 1.5 times lower to their annual NAAQS levels, respectively. The seasonal mean mass concentrations of all the pollutants were found to be highest during the winter/post-monsoon season at both the sites, which are more pronounced at industrial site compared to residential site. The observed high pollutants over the station during the winter/post-monsoon season were found to be largely associated with the air mass back-trajectories from N-NW direction.

The impact of traffic on air quality in Ireland: insights from the simultaneous kerbside and suburban monitoring of submicron aerosols

To evaluate the impact of traffic on urban air quality, the chemical composition of submicron aerosols (PM1) and sources of organic aerosol (OA) were simultaneously investigated at a kerbside site in the Dublin city center and a residential site in suburban Dublin (∼ 5 km apart) from 4 September to 9 November in 2018. Through the detailed comparison of a 1-week nonheating period from 10 to 17 September and a 1-week heating period from 27 October to 4 November, black carbon (BC) was found to be the most dominant component (38 %–55 % or 5.6–7.1 µg m−3) of PM1 at the kerbside, while OA was the most important (46 %–64 % of PM1 or 1.0–8.1 µg m−3) at the residential site. The daily and weekly cycle of BC at the kerbside during the nonheating period pointed to the major source of vehicular emissions, consistent with that for nitrogen oxides (NOx). However, traffic emissions were found to have a minor impact on air quality at the residential site, due to its distance from traffic sources and the effects of wind speed and wind direction. As a result of vehicular emissions and the street canyon effect, the kerbside increment (from the urban background) ratio of up to 25 : 1 was found for BC during the nonheating period but reduced to 10 : 1 during the heating period due to the additional sources of solid fuel burning impacting the air quality at both sites simultaneously. OA source analysis shows only 16 %–28 % (0.9–1.0 µg m−3; upper limit for traffic due to the additional heating source of hydrocarbon-like OA – HOA) of OA at the kerbside associated with vehicular emissions, with higher contributions from cooking (18 %–36 % or 1.2 µg m−3), solid fuel burning (38 % or 2.4 µg m−3; resolved only during the heating period), and oxygenated OA (29 %–37 % or 1.2–1.9 µg m−3). At the residential site, solid fuel burning contributed to 60 % (4.9 µg m−3) of OA during the heating period, while oxygenated OA (OOA) accounted for almost 65 % (0.6 µg m−3) of OA during the nonheating period. Based on simultaneous investigations of PM1 at different urban settings (i.e., residential versus kerbside), this study highlights the temporal and spatial variability of sources within the Dublin city center and the need for additional aerosol characterization studies to improve targeted mitigation solutions for greater impact on urban air quality. Moreover, traffic and residential heating may hold different implications for health and climate, as indicated by the significant increment of BC at the kerbside and the large geographic impact of OA from residential heating at both the kerbside and residential sites.

Comparative study of Ambient Air Quality of Jalna City (MS), India

Comparative study of ambient air quality of Jalna city was carried using air quality index (AQI). Air pollutants concentration-SO2, NOx, RSPM and NRSPM at residential and industrial sites for years 2016 and 2017 were compared. The monthly, seasonal and annual AQI values determined at both residential and industrial sites for these years. Results suggest better air quality at residential site for the year 2017 than 2016. While at industrial site better air quality was observed for the year 2016 than 2017. Government regulations, effective treatments in industries, appropriate waste disposal helped in minimization of pollution levels. For both the years and at both sites annual mean concentrations of SO2 and NOx were found within the permissible limits of Indian National Ambient Air Quality standards (NAAQS), although for both the years and at both the sites RSPM and NRSPM concentrations were observed above the norms. The annual AQI value at residential site was higher 128 for 2016 compared to 120 for 2017. While at industrial site AQI value 88 was found lower for 2016 compared to higher 126 for the year 2017.