Ozone in the Los Angeles Atmosphere

Renzetti, N. A.

doi:10.1063/1.1742639

Cited by 21 publications

(8 citation statements)

References 2 publications

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“…It was recognized that the type of urban air pollution in Los Angeles was chemically different from that experienced elsewhere (see section 3). Los Angeles smog is highly oxidizing; in the 1940s and 1950s it was known to contain ozone but the contributions of other oxidants, such as NO 2 and H 2 O 2 , were unclear (Renzetti 1956). Blacet in 1952 recognized that the photolysis of NO 2 could be an important source of ozone in polluted urban air (Blacet 1952).…”

Section: Tropospheric Chemistry a Early Studies Of Photochemical Smogmentioning

confidence: 99%

100 Years of Progress in Gas-Phase Atmospheric Chemistry Research

Wallington

Seinfeld

Barker

2019

Meteorological Monographs

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Remarkable progress has occurred over the last 100 years in our understanding of atmospheric chemical composition, stratospheric and tropospheric chemistry, urban air pollution, acid rain, and the formation of airborne particles from gas-phase chemistry. Much of this progress was associated with the developing understanding of the formation and role of ozone and of the oxides of nitrogen, NO and NO2, in the stratosphere and troposphere. The chemistry of the stratosphere, emerging from the pioneering work of Chapman in 1931, was followed by the discovery of catalytic ozone cycles, ozone destruction by chlorofluorocarbons, and the polar ozone holes, work honored by the 1995 Nobel Prize in Chemistry awarded to Crutzen, Rowland, and Molina. Foundations for the modern understanding of tropospheric chemistry were laid in the 1950s and 1960s, stimulated by the eye-stinging smog in Los Angeles. The importance of the hydroxyl (OH) radical and its relationship to the oxides of nitrogen (NO and NO2) emerged. The chemical processes leading to acid rain were elucidated. The atmosphere contains an immense number of gas-phase organic compounds, a result of emissions from plants and animals, natural and anthropogenic combustion processes, emissions from oceans, and from the atmospheric oxidation of organics emitted into the atmosphere. Organic atmospheric particulate matter arises largely as gas-phase organic compounds undergo oxidation to yield low-volatility products that condense into the particle phase. A hundred years ago, quantitative theories of chemical reaction rates were nonexistent. Today, comprehensive computer codes are available for performing detailed calculations of chemical reaction rates and mechanisms for atmospheric reactions. Understanding the future role of atmospheric chemistry in climate change and, in turn, the impact of climate change on atmospheric chemistry, will be critical to developing effective policies to protect the planet.

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Section: Tropospheric Chemistry a Early Studies Of Photochemical Smogmentioning

confidence: 99%

100 Years of Progress in Gas-Phase Atmospheric Chemistry Research

Wallington

Seinfeld

Barker

2019

Meteorological Monographs

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“…Since the 1950s, the Los Angeles (LA) basin has been well known for its photochemically induced air pollution or urban smog with high ozone levels [ Haagen‐Smit , 1952; Renzetti , 1956]. The air quality problem in the LA basin or also called South Coast Air basin is so severe because of the very high population density (about 13 million people) and the very inefficient ventilation of the basin causing the pollution to be trapped inside.…”

Section: Introductionmentioning

confidence: 99%

Multiyear trends in volatile organic compounds in Los Angeles, California: Five decades of decreasing emissions

et al. 2012

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[1] Airborne measurements of volatile organic compounds (VOCs) were performed during CalNex 2010 (California Research at the Nexus of Air Quality and Climate Change) in the Los Angeles (LA) basin in May-June 2010 and during ITCT2k2 (Intercontinental Transport and Chemical Transformation) in May 2002. While CO 2 enhancements in the basin were similar between the two years, the DCO/DCO 2 ratio had decreased by about a factor of two. The DVOC/DCO emission ratios stayed relatively constant between the two years. This indicates that, relative to CO 2 , VOCs in the LA basin also decreased by about a factor of two since 2002. These data are compared with the results from various previous field campaigns dating back as early as 1960 and from the extensive air quality monitoring system in the LA basin going back to 1980. The results show that the mixing ratios of VOCs and CO have decreased by almost two orders of magnitude during the past five decades at an average annual rate of about 7.5%. Exceptions to this trend are the small alkanes ethane and propane, which have decreased slower due to the use and production of natural gas. A comparison with trends in London, UK shows that, due to stricter regulations at the time, VOC mixing ratios in LA decreased earlier than in London, albeit at a slower rate, such that typical mixing ratios in both cities in 2008 were at about the same level.

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“…Photochemical smog and air pollution with high ozone levels are a problem for many cities in the United States and elsewhere. In the Los Angeles (LA) basin the air pollution problem has been well documented and studied since the 1950s [ Haagen‐Smit , ; Renzetti , ]. The large population (about 13 million people) and the inefficient ventilation of the basin exacerbate the problem.…”

Section: Introductionmentioning

confidence: 99%

Photochemical aging of volatile organic compounds in the Los Angeles basin: Weekday‐weekend effect

et al. 2013

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[1] During the CalNex (California Research at the Nexus of Air Quality and Climate Change) field study in May-June 2010, measurements of volatile organic compounds (VOCs) were performed in the Los Angeles (LA) basin onboard a NOAA research aircraft and at a ground site located in Pasadena. A weekday-weekend effect in ozone, caused by lower NO x emissions due to reduced diesel truck traffic in the weekends, has been previously observed in Los Angeles and other cities. Measurements in the Caldecott tunnel show that emission ratios of VOCs do not vary with the day of the week, but measurements during CalNex2010 show a VOC weekday-weekend effect through faster photochemical processing at lower ambient NO x mixing ratios. Ambient VOC enhancement ratios of long-lived species such as benzene are the same between weekdays and weekends, whereas enhancement ratios of short-lived species, such as trimethyl benzene, are up to a factor of three lower on weekends. Based upon the observed differences in VOC enhancement ratios to CO, we determine that photochemical processing was on average 65%-75% faster on weekends during CalNex2010, which indicates that ambient OH radical concentrations were larger by this factor causing the observed change in VOC composition. A box model calculation based on the Master Chemical Mechanism was used to verify the increase in photochemical processing in the weekends.

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Ozone in the Los Angeles Atmosphere

Cited by 21 publications

References 2 publications

100 Years of Progress in Gas-Phase Atmospheric Chemistry Research

100 Years of Progress in Gas-Phase Atmospheric Chemistry Research

Multiyear trends in volatile organic compounds in Los Angeles, California: Five decades of decreasing emissions

Photochemical aging of volatile organic compounds in the Los Angeles basin: Weekday‐weekend effect

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