On Thursday, July 25, 2019, Pima County Department of Environmental Quality’s (PDEQ) air quality monitors at Saguaro Park East and Children’s Memorial Park recorded exceedances of the EPA health standard for ground-level ozone. These were the first ozone exceedances reported during the 2019 ozone season which began in April. For comparison purposes, the Phoenix area has exceeded the ozone standard 20 times so far in 2019.
By this time last year, air quality in Pima County had exceeded the EPA health standard three times at Saguaro Park East and twice at Children’s Memorial Park. When combined with the two previous year’s exceedances, the 2018 ozone levels caused the Pima County region to violate the EPA ozone standard for the first time.
Ground-level ozone is an air pollutant that is formed by a photochemical reaction that occurs when intense sunlight reacts with emissions from various sources such as motor vehicles, power plants, industries and certain types of vegetation. When elevated, ozone can cause difficulty breathing and can aggravate preexisting respiratory diseases.
“Because of how EPA defines a violation of the ozone standard, we may not know if we violated the standard until the ozone season is over in September,” said Beth Gorman, Senior Program Manager with PDEQ. “In the meantime, reducing emissions that create ozone could help avoid another ozone violation and regulatory restrictions on businesses. Combining trips, sharing rides, avoiding engine idling, refueling after 6 p.m. and conserving electricity are ways we can each take action to improve air quality in Pima County,” said Gorman.
Real-time air quality data is available on the PDEQ website at
www.pima.gov/deq.