Tough Californian vehicles emissions standards have decreased air pollution levels in Los Angeles, according to researchers' findings.
Even though, compared to 1960, there are three times as many private motor vehicles driving along roads in southern California, the air has actually become cleaner, the researchers say. Particularly noticeable is a drop in levels of airborne peroxyacetyl nitrate: a known eye irritation source.
"LA's air has lost a lot of its 'sting", commented the National Oceanic and Atmospheric Association's IIana Pollack, who led this study.
Alongside the peroxyacetyl nitrate drop, ozone levels have also decreased. That said, the American Lung Association believes Los Angeles still has higher ozone levels than any other city in the United States.
LA Air Pollution Study
Headed by Pollack, the LA air pollution study involved atmospheric data comparisons, using information dating back to 1960 and going up to 2010. Combined, these data sets provided a regional atmospheric model covering many decades and showing a key drop in nitrogen oxides and VOCs (volatile organic compounds): the substances responsible for air pollution build-up.
Famously, California's strict environmental laws limit the emissions legally allowed to be released by cars sold or driven there. Despite the healthy air pollution drop, motor vehicles remain Los Angeles' major air pollution source, the researchers say.
Los Angeles Pollution Drops
"To most people the big deal is that things have got a lot better," added Pollack. "But, as scientists, we want to know how they have got better."
The researchers hope their findings will give policymakers new impetus when it comes to delivering further Los Angeles pollution drops. "Our work aims to interpret the past and present observations, with the aim of informing future decisions", Pollack explained.
Their work will now appear in an upcoming printed edition of the American Geophysical Union's Journal of Geophysics Research: Atmospheres, after having appeared in the online edition at the end of May.
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