The increased vehicle emissions standards that are being enforced in California may be helping to lessen the pollution in the state, especially around cities such as Los Angeles, according to a press release from the University of Colorado, Boulder.
The decrease in pollution is surprising because the population of the city has increased by three times since the 1960s.
There is less organic nitrate in the air, which can sting eyes. There is also less ozone pollution.
"This is good news: LA's air has lost a lot of its 'sting,' " said lead author of the study Ilana Pollack, a CIRES scientist who works at the NOAA Earth System Research Lab. Boulder. "Our study shows exactly how that happened, and confirms that California's policies to control emissions have worked as intended."
Scientists have been measuring the pollutants in the ozone of the Los Angeles area since the 1960s. Their tests measure pollutants that are "formed in the atmosphere," and chemicals that come directly from sources such as cars, factories, and even vegetation.
When the studies originally found the pollution levels to be high, policies were put in place to lower emissions. The latest tests have revealed that the policies have been working even though there are almost three times more cars on the road than there were when the testing began.
"The emission reductions have 'flipped' some of the chemistry that takes place in the atmosphere," Pollack said. "The relevant precursors in the atmosphere now favor chemical pathways that are more likely to produce nitric acid, and less likely to make ozone and peroxyacetyl nitrate (PAN)."
PAN is the pollutant that is associated with stinging eyes.
"Compiling long-term trends in precursors and secondary products, then seeing all the data together on paper, really made changes in the chemistry stand out," Pollack said. "Our work aims to interpret the past and present observations, with an eye toward informing future decisions," Pollack said.
