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Vehicle Emissions and Air Quality: The Early Years (1940s–1950s)

Desert Research Institute, Reno, NV 89512, USA
Chevron Products Company, San Ramon, CA 94583, USA
Author to whom correspondence should be addressed.
Academic Editor: Kenichi Tonokura
Atmosphere 2021, 12(10), 1354;
Received: 13 September 2021 / Revised: 11 October 2021 / Accepted: 13 October 2021 / Published: 16 October 2021
(This article belongs to the Special Issue Air Quality Impacts of Vehicle Emissions)
During the 1940s, an unusual form of air pollution was experienced in the Los Angeles (LA) area of Southern California. Referred to as LA smog, this pollution differed from previously known air pollution with respect to its temporal patterns (daytime formation and nighttime dissipation), eye irritation, high oxidant levels, and plant damage. Early laboratory and field experimentation discovered the photochemical origins of LA smog. Though mechanistic understanding was incomplete, it was determined that hydrocarbon (HC) compounds in the atmosphere participate in smog formation, enabling build-up of higher ozone concentrations than would otherwise occur. It being a significant source, there was great interest in characterizing and controlling HC emissions from motor vehicles. Considerable work was done in the 1940s and 1950s to understand how emissions varied with vehicle operating conditions and deterioration of engine components. During this time, procedures were developed (and improved) to sample and quantify vehicle emissions. Besides exhaust, HC emissions from crankcase blowby, carburetor evaporation, and fuel tank losses were measured and characterized. Initial versions of both catalytic and non-catalytic exhaust after-treatment systems were developed. The knowledge gained from this pre-1960 work laid the foundation for many advancements that reduced vehicle emissions and improved air quality during subsequent decades. View Full-Text
Keywords: smog; air pollution; vehicle emissions; pre-1960; ozone; photochemistry; Los Angeles smog; air pollution; vehicle emissions; pre-1960; ozone; photochemistry; Los Angeles
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MDPI and ACS Style

Hoekman, S.K.; Welstand, J.S. Vehicle Emissions and Air Quality: The Early Years (1940s–1950s). Atmosphere 2021, 12, 1354.

AMA Style

Hoekman SK, Welstand JS. Vehicle Emissions and Air Quality: The Early Years (1940s–1950s). Atmosphere. 2021; 12(10):1354.

Chicago/Turabian Style

Hoekman, S. K., and J. S. Welstand 2021. "Vehicle Emissions and Air Quality: The Early Years (1940s–1950s)" Atmosphere 12, no. 10: 1354.

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