Yesterday marked the summer solstice and the third time this year air quality in Pima County exceeded the U.S. Environmental Protection Agency’s (EPA) National Ambient Air Quality Standard (NAAQS) for ground-level ozone pollution. One more exceedance and Pima County will officially violate the EPA health standard. There is a strong possibility ozone levels may be high again today.
The EPA standard allows several exceedances before a community is considered in violation of the ozone standard. Pima County Department of Environmental Quality’s air quality monitors have recorded enough exceedances of the ozone standard to put the area in jeopardy of being determined non-attainment by the federal government. If EPA designates Pima County as non-attainment of the standard, there will likely be additional regulations that affect businesses and transportation planning.
“Ozone is a complicated pollutant because it is formed as a result of a photochemical reaction between other pollutants, under specific meteorological conditions that are beyond our control,” said Ursula Nelson, Pima County Department of Environmental Quality’s Director. “What we can control are the pollutants we put into the air during the day and that can help reduce the formation of ozone,” said Nelson. Ground-level ozone is damaging to human health and should not be confused with the naturally occurring ozone layer that protects the planet from solar radiation.
Motor vehicle use (both tailpipe emissions and fumes from refueling), emissions from commercial operations, and volatile organic compounds from some types of vegetation release the precursors to ground-level ozone. Reducing the amount of driving and engine idling that occurs during the day will decrease the emissions that form ozone. More information about ozone is available on PDEQ’s
website.