Wednesday’s bright summer skies were hiding an annual Spokane health threat: ozone pollution.
The Spokane Regional Clean Air Agency issued a forecast for deteriorating air quality as a result of temperatures near 90 degrees through this afternoon.
The agency said air quality would drop from the good range at midday on Wednesday to the moderate range by today.
“It is a health concern,” said Lisa Woodard, spokeswoman for the agency.
Cooler weather is expected on Friday through Sunday, with highs in the 70s.
Ozone forms when volatile compounds such as gasoline fumes, vehicle exhaust and oxides of nitrogen react with the sun and heat.
While high-elevation ozone filters dangerous ultraviolet light, it is an irritant to the lungs. People with breathing problems are especially susceptible to respiratory distress when ozone is high, Woodard said.
Prolonged exposure can reduce lung function and cause permanent damage.
In the past 11 years, Spokane’s ozone pollution has approached but stayed below the threshold for a violation of federal air quality standards.
However, the U.S. Environmental Protection Agency is about to tighten the air quality standards for ozone, which potentially could put Spokane into violation during summer hot spells, Woodard said.
Currently, the maximum amount of ozone under the standard is 0.075 parts per million. The new standard is likely to be below 0.070 ppm.
Spokane has seen a steady reduction in its average ozone pollution since 2004. Last year’s average was 0.060 ppm, down from 0.073 in 2003 and 2004.
The downward trend resulted from increased bus ridership; installation of vapor recovery units on gasoline pumps at major retailers; industrial pollution controls; and less severe summer heat, air quality officials said.
Members of the public can help reduce ozone in the following ways:
• Reduce vehicle trips.
• Use alternate transportation.
• Refuel during the cool part of the day.
• Switch to electric lawn and garden equipment.
• Avoid using lighter fluid on charcoal.
• Shut down vehicles rather than keep them idling.
• Keep tires inflated properly to use less fuel.