Some Unique Aspects of Air Pollution in Los Angeles

Littman, F.E.; Magill, Paul L.

doi:10.1080/00966665.1953.10467586

Cited by 9 publications

(6 citation statements)

References 2 publications

(2 reference statements)

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“…Most of the ozone distributed in the stratosphere can absorb strong ultraviolet radiation that can cause health problems in humans ( Bell et al, 2004 ; Norval et al, 2007 ; Su et al, 2017 ; Nuvolone et al, 2018 ; Zhang et al, 2020 ). A small amount of ozone in the troposphere, which is mainly produced from the photochemical reaction between volatile organic compounds (VOCs) and nitrogen dioxides (NO x ) ( Littman and Magill, 1953 ; Sillman, 1995 ), shows harmful effects to humans. Therefore, the vertical distribution of ozone is very important for us to understand the physicochemical process of ozone.…”

Section: Introductionmentioning

confidence: 99%

Ozone profile retrievals from TROPOMI: Implication for the variation of tropospheric ozone during the outbreak of COVID-19 in China

Zhao

Liu

Cai

et al. 2021

Science of The Total Environment

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During the outbreak of the coronavirus disease 2019 (COVID-19) in China in January and February 2020, production and living activities were drastically reduced to impede the spread of the virus, which also caused a strong reduction of the emission of primary pollutants. However, as a major species of secondary air pollutant, tropospheric ozone did not reduce synchronously, but instead rose in some region. Furthermore, higher concentrations of ozone may potentially promote the rates of COVID-19 infections, causing extra risk to human health. Thus, the variation of ozone should be evaluated widely. This paper presents ozone profiles and tropospheric ozone columns from ultraviolet radiances detected by TROPOospheric Monitoring Instrument (TROPOMI) onboard Sentinel 5 Precursor (S—5P) satellite based on the principle of optimal estimation method. We compare our TROPOMI retrievals with global ozonesonde observations, Fourier Transform Spectrometry (FTS) observation at Hefei (117.17°E, 31.7°N) and Global Positioning System (GPS) ozonesonde sensor (GPSO 3 ) ozonesonde profiles at Beijing (116.46°E, 39.80°N). The integrated Tropospheric Ozone Column (TOC) and Stratospheric Ozone Column (SOC) show excellent agreement with validation data. We use the retrieved TOC combining with tropospheric vertical column density (TVCD) of NO 2 and HCHO from TROPOMI to assess the changes of tropospheric ozone during the outbreak of COVID-19 in China. Although NO 2 TVCD decreased by 63%, the retrieved TOC over east China increase by 10% from the 20-day averaged before the lockdown on January 23, 2020 to 20-day averaged after it. Because the production of ozone in winter is controlled by volatile organic compounds (VOCs) indicated by monitored HCHO, which did not present evident change during the lockdown, the production of ozone did not decrease significantly. Besides, the decrease of NO x emission weakened the titration of ozone, causing an increase of ozone.

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Section: Introductionmentioning

confidence: 99%

Ozone profile retrievals from TROPOMI: Implication for the variation of tropospheric ozone during the outbreak of COVID-19 in China

Zhao

Liu

Cai

et al. 2021

Science of The Total Environment

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“…Air pollution has been mostly associated with urban pollution (2). It originated in big cities such as London and Los Angeles in the previous century (3,4). Routinely, we see lists of the most polluted cities globally, again emphasizing the connection between air pollution and urban areas, with PM 2.5 being the dominant pollutant in the last few decades (5).…”

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confidence: 99%

Outdoor air pollution in India is not only an urban problem

Ravishankara

David

Pierce

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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Urban outdoor air pollution in the developing world, mostly due to particulate matter with diameters smaller than 2.5 µm (PM2.5), has been highlighted in recent years. It leads to millions of premature deaths. Outdoor air pollution has also been viewed mostly as an urban problem. We use satellite-derived demarcations to parse India’s population into urban and nonurban regions, which agrees with the census data. We also use the satellite-derived surface PM2.5 levels to calculate the health impacts in the urban and nonurban regions. We show that outdoor air pollution is just as severe in nonurban regions as in the urban regions of India, with implications to monitoring, regulations, health, and policy.

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“…The combination of sunlight 30 and high VOCs is ideal for the formation of ozone. The Pacific inversion layer over southern California and mountains that form a natural basin act together to keep pollutants from dissipating (Littman and Magill, 1953). As such, Riverside, CA is an ideal test bed to answer our question.…”

mentioning

confidence: 99%

Intra-urban spatial variability of surface ozone and carbon dioxide in Riverside, CA: viability and validation of low-cost sensors

Sadighi

Coffey

Polidori

et al. 2017

Preprint

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Abstract. Sensor networks are being more widely used to characterize and understand compounds in the atmosphere such as ozone and carbon dioxide. This study employs a measurement tool, called the U-Pod, constructed at the University of Colorado Boulder, to investigate spatial and temporal variability of O3 and CO2 in a 314 km 2 area of Riverside County near Los Angeles, 10California. This tool provides low-cost sensors to collect ambient data at non-permanent locations. The U-Pods were calibrated using a pre-deployment field calibration technique; all the U-Pods were collocated with regulatory monitors. After collocation, the U-Pods were deployed in the area mentioned. A subset of pods was deployed at two local regulatory air quality monitoring stations providing validation for the collocation calibration method. Field validation of sensor O3 and CO2 measurements to minute resolution reference observations resulted in R-squared and root mean squared errors (RMSE) of 0.95 -0.97 and 4.4 -15 7.2 ppbv for O3 and 0.79 and 15 ppmv CO2, respectively. Using the deployment data, ozone and carbon dioxide concentrations were observed to vary on this small spatial scale. In the analysis based on hourly binned data, the median R-squared values between all possible U-Pod pairs varied from 0.52 to 0.86 for ozone during the deployment. The medians of absolute differences were calculated between all possible pod pairs, 21 pairs total. The median values of those median absolute differences for each hour of the day varied between 2.2 and 9.3 ppb for the ozone deployment. For carbon dioxide, distributions 20 of all measurements vary from 413 -425 ppm during the calibration (collocation) and 406 -472 during the deployment. Since median differences between U-Pod concentrations during deployment are larger than the respective root mean square error values for ozone and carbon dioxide, we can conclude that there is spatial variability in these pollutants across the study area. This is important because it means that citizens may be exposed to more ozone than they would assume based on current regulatory monitoring. 25Atmos. Meas. Tech. Discuss., https://doi

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Some Unique Aspects of Air Pollution in Los Angeles

Cited by 9 publications

References 2 publications

Ozone profile retrievals from TROPOMI: Implication for the variation of tropospheric ozone during the outbreak of COVID-19 in China

Ozone profile retrievals from TROPOMI: Implication for the variation of tropospheric ozone during the outbreak of COVID-19 in China

Outdoor air pollution in India is not only an urban problem

Intra-urban spatial variability of surface ozone and carbon dioxide in Riverside, CA: viability and validation of low-cost sensors

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