Technology-forcing or Technology-following? -Evolution of air pollutant emission standards in the United States-

The unequal spatial distribution of ambient nitrogen dioxide (NO2), an air pollutant related to traffic, leads to higher exposure for minority and low socioeconomic status communities. We exploit the unprecedented drop in urban activity during the COVID-19 pandemic and use high-resolution, remotely sensed NO2 observations to investigate disparities in NO2 levels across different demographic subgroups in the United States. We show that, prior to the pandemic, satellite-observed NO2 levels in the least White census tracts of the United States were nearly triple the NO2 levels in the most White tracts. During the pandemic, the largest lockdown-related NO2 reductions occurred in urban neighborhoods that have 2.0 times more non-White residents and 2.1 times more Hispanic residents than neighborhoods with the smallest reductions. NO2 reductions were likely driven by the greater density of highways and interstates in these racially and ethnically diverse areas. Although the largest reductions occurred in marginalized areas, the effect of lockdowns on racial, ethnic, and socioeconomic NO2 disparities was mixed and, for many cities, nonsignificant. For example, the least White tracts still experienced ∼1.5 times higher NO2 levels during the lockdowns than the most White tracts experienced prior to the pandemic. Future policies aimed at eliminating pollution disparities will need to look beyond reducing emissions from only passenger traffic and also consider other collocated sources of emissions such as heavy-duty vehicles.

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Evaluation of Pollutants Along the National Road N2 in Togo using the AERMOD Dispersion Model

Journal of Health and Pollution ◽

10.5696/2156-9614-10.27.200908 ◽

2020 ◽

Vol 10 (27) ◽

Author(s):

Yawovi Mignanou Amouzouvi ◽

Milohum Mikesokpo Dzagli ◽

Koffi Sagna ◽

Zoltán Török ◽

Carmen Andreea Roba ◽

...

Keyword(s):

Environmental Protection Agency ◽

Dispersion Model ◽

The United States ◽

Air Pollutant ◽

World Health ◽

Pollutant Emission ◽

Permissible Limits ◽

European Environmental Agency ◽

The World ◽

National Road

Background. Air pollution has become a major problem around the world and is increasingly an issue in Togo due to increased vehicular traffic. Gaseous pollutants are released by engines and are very harmful to human health and the environment. The fuels used on the major road in Togo, the N2, are adulterated with unknown contents and are of poor quality. Many of the vehicles come from neighboring countries, such as Benin, Ghana and Nigeria. Objectives. The present study aims to evaluate the pollution rate in Togo through the estimation of the concentrations of sulfur dioxide (SO2), nitrogen oxides (NOx), and particular matter (PM) on the international road, the National Road N2, in Lomé, compared to the World Health Organization's (WHO) standard limit. Methods. The simulations of pollutant concentration were performed using the Industrial Source Complex Short Term Version 3 model, which is included in the United States Environmental Protection Agency Regulatory Model (USEPA) AERMOD View software. The meteorological averages data were obtained from the local station near the National Road N2 in Togo in 2018. Hourly averages were calculated according to the European Monitoring Evaluation Programme/European Environmental Agency air pollutant emission inventory guidebook 2016 and were processed using AERMET View and a terrain pre-processor, AERMAP. For the model, the sources of pollution were the vehicles traveling on the road segment. The source was a line volume with 20 m of width and 2 m of height. The estimation methodology covered exhaust emissions of NOx, SO2 and PM contained in the fuel. Results. The simulations provided average hourly, daily and annual concentrations of the different pollutants: 71.91 μg/m3, 42.41 μg/m3,11.23 μg/m3 for SO2; 16.78 μg/m3, 9.89 μg/m3, 2.46 μg/m3 for NOx and below the detection limit, 0.62 μg/m3, 0.15 μg/m3 for PM, respectively. These results indicate that on the National Road N2 in Togo, the concentrations of SO2 were high compared to those of NOx and PM. The daily average concentration of SO2 was twice the permissible limits set by the WHO. Conclusions. Emissions obtained from the AERMOD for NOx and PM were less than the permissible limits set by the WHO, while the rate of SO2 was twice the permissible limit. The fuels used on this road were very rich in sulfur. The sulfur level in fuels must be monitored by stakeholders in Togo. Competing Interests. The authors declare no competing financial interests.

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Hazardous air pollutant exposure as a contributing factor to COVID-19 mortality in the United States

Environmental Research Letters ◽

10.1088/1748-9326/abaf86 ◽

2020 ◽

Vol 15 (9) ◽

pp. 0940a9 ◽

Cited By ~ 2

Author(s):

Michael Petroni ◽

Dustin Hill ◽

Lylla Younes ◽

Liesl Barkman ◽

Sarah Howard ◽

...

Keyword(s):

United States ◽

The United States ◽

Air Pollutant ◽

Hazardous Air Pollutant

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Assessment of the effect of air pollution controls on trends in shortwave radiation over the United States from 1995 through 2010 from multiple observation networks

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-13-23719-2013 ◽

2013 ◽

Vol 13 (9) ◽

pp. 23719-23755 ◽

Cited By ~ 1

Author(s):

C.-M. Gan ◽

J. Pleim ◽

R. Mathur ◽

C. Hogrefe ◽

C. N. Long ◽

...

Keyword(s):

United States ◽

Cloud Cover ◽

Surface Concentration ◽

The United States ◽

Air Pollutant ◽

Shortwave Radiation ◽

Clear Sky ◽

Western Us ◽

The Us ◽

Increasing Trends

Abstract. Long term datasets of all-sky and clear-sky downwelling shortwave (SW) radiation, cloud cover fraction and aerosol optical depth (AOD) are analyzed together with surface concentration from several networks (e.g. SURFRAD, CASTNET, IMPROVE and ARM) in the United States (US). Seven states with varying climatology are selected to better understand the effects of aerosols and clouds on SW radiation. This analysis aims to assess the effects of reductions in anthropogenic aerosol burden resulting from substantial reductions in emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) over the past 16 yr across the US on trends in SW radiation. The SO2 and NOx emission data show decreasing trends from 1995 to 2010 which indirectly validates the effects of the Clean Air Act (CAA) in the US. Meanwhile, the total column AOD and surface total PM2.5 observations also show decreasing trends in the eastern US but slightly increasing trends in the western US. Moreover, measured surface concentrations of several other pollutants (i.e. SO2, SO4 and NOx) have the same behavior as the AOD and total PM2.5. First, all-sky downwelling SW radiation is assessed together with the cloud cover. Results of this analysis show strong increasing trends in all-sky downwelling SW radiation with decreasing trends in cloud cover. However, since observations of both all-sky direct and diffuse SW radiation are increasing, there may be other factors contributing to the radiation trends in addition to the decreasing trends in overall cloud cover. To investigate the role of direct radiative effects of aerosols, clear-sky downwelling radiation is analyzed so that cloud effects are eliminated. However, similar increasing trends in clear-sky direct and diffuse SW radiation are observed. While significantly decreasing trends in AOD and surface concentration along with increasing SW radiation (both all-sky and clear-sky) in the eastern US during 1995–2010 imply the occurrence of direct aerosol mediated "brightening", the increasing trends of both all-sky and clear sky diffuse SW radiation contradicts this conclusion since diffuse radiation would be expected to decrease as aerosols direct effects decrease. After investigating several confounding factors, the increasing trend in diffuse SW may be due to more high-level cirrus from increasing air traffic over the US. In contrast to the eastern US, radiation observations in the western US do not show any indication of "brightening" which is consistent with the observations (e.g. AOD, PM2.5 and surface concentration) that show the aerosol loading increasing slightly. This outcome is not unexpected because the CAA controls were mainly aimed at reducing air pollutants emission in the eastern US and air pollutant level in the western US are much lower.

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Life-Cycle Greenhouse Gas and Criteria Air Pollutant Emissions of Electric Vehicles in the United States

SAE International Journal of Alternative Powertrains ◽

10.4271/2013-01-1283 ◽

2013 ◽

Vol 2 (2) ◽

pp. 325-336 ◽

Cited By ~ 2

Author(s):

Hao Cai ◽

Michael Wang ◽

Amgad Elgowainy ◽

Jeongwoo Han

Keyword(s):

United States ◽

Life Cycle ◽

Greenhouse Gas ◽

Electric Vehicles ◽

The United States ◽

Air Pollutant ◽

Pollutant Emissions

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Assessment of the effect of air pollution controls on trends in shortwave radiation over the United States from 1995 through 2010 from multiple observation networks

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-1701-2014 ◽

2014 ◽

Vol 14 (3) ◽

pp. 1701-1715 ◽

Cited By ~ 31

Author(s):

C.-M. Gan ◽

J. Pleim ◽

R. Mathur ◽

C. Hogrefe ◽

C. N. Long ◽

...

Keyword(s):

United States ◽

Cloud Cover ◽

The United States ◽

Air Pollutant ◽

Pollutant Emissions ◽

Clear Sky ◽

Western Us ◽

The Us ◽

Clean Air ◽

Increasing Trends

Abstract. Long-term data sets of all-sky and clear-sky downwelling shortwave (SW) radiation, cloud cover fraction, and aerosol optical depth (AOD) were analyzed together with surface concentrations from several networks (e.g., Surface Radiation Budget Network (SURFRAD), Clean Air Status and Trend Network (CASTNET), Interagency Monitoring of Protection Visual Environments (IMPROVE) and Atmospheric Radiation Measurement (ARM)) in the United States (US). Seven states with varying climatology were selected to better understand the effects of aerosols and clouds on SW radiation. This analysis aims to assess the effects of reductions in anthropogenic aerosol burden resulting from substantial reductions in emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) over the past 16 yr across the US, based on trends in SW radiation. The SO2 and NOx emission data show decreasing trends from 1995 to 2010, which indirectly validates the effects of the Clean Air Act (CAA) in the US. Meanwhile, the total column AOD and surface total PM2.5 observations also show decreasing trends in the eastern US but slightly increasing trends in the western US. Moreover, measured surface concentrations of several other pollutants (i.e., SO2, SO4 and NOx) have similar behavior to AOD and total PM2.5. Analysis of the observed data shows strong increasing trends in all-sky downwelling SW radiation with decreasing trends in cloud cover. However, since observations of both all-sky direct and diffuse SW radiation show increasing trends, there may be other factors contributing to the radiation trends in addition to the decreasing trends in overall cloud cover. To investigate the role of direct radiative effects of aerosols, clear-sky downwelling radiation is analyzed so that cloud effects are eliminated. However, similar increasing trends in clear-sky total and diffuse SW radiation are observed. While significantly decreasing trends in AOD and surface PM2.5 concentrations along with increasing SW radiation (both all-sky and clear-sky) in the eastern US during 1995–2010 imply the occurrence of direct aerosol mediated "brightening", the increasing trends of both all-sky and clear-sky diffuse SW radiation contradicts this conclusion since diffuse radiation would be expected to decrease as aerosols direct effects decrease and cloud cover decreases. After investigating several confounding factors, the increasing trend in clear-sky diffuse SW may be due to more high-level cirrus from increasing air traffic over the US. The clear-sky radiation observations in the western US also show indications of "brightening" even though the AOD, PM2.5 and surface concentration do not vary drastically. This outcome was not unexpected because the CAA controls were mainly aimed at reducing air pollutant emissions in the eastern US and air pollutant levels in the western US were much lower at the onset. This suggests other factors affect the "brightening" especially in the western US.

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