A more restrictive ozone standard in place this year means residents in Louisiana and other states should expect to see more ozone action days called this summer during forecasted hot and windless days.
Hot, sunny and relatively windless days last week resulted in ozone action days being called for by state Department of Environmental Quality officials.
An ozone action day was also called for Monday and conditions for ozone formation will likely continue through Wednesday with the forecast from DEQ’s EnviroFlash system calling for light winds and high temperatures.
Ozone forms when nitrogen oxides and hydrocarbons from car exhaust, industrial activities and other sources combine in the air during hot and sunny days.
When there isn’t much wind, this ozone accumulates and can cause breathing and health problems, especially for vulnerable populations such as children.
On Wednesday, it’s possible that slightly stronger winds and afternoon storms could help disperse some ozone pollution, according to the forecast, but the Air Quality Index will still be in mid- to high-moderate range. The AQI lists air quality based on categories of good, moderate, unhealthy for sensitive groups, unhealthy and very unhealthy.
“It’s not as much the heat as it is the sunlight with the stagnant conditions,” said Tim Bergeron, DEQ environmental chemical specialist. “That’s what give us these days. The pollutants haven’t changed from last week.”
The ozone standard is calculated by taking the fourth-highest 8-hour-average ozone reading of the year and averaging three years of those readings.
A previous federal standard for ozone was set at 80 parts per billion with a rounding that allowed up to 85 parts per billion. A new ozone standard announced earlier this year puts that limit at 75 parts per billion. More than 75 parts per billion puts an area over the federal standard.
Wednesday, there were exceedances of the ozone standard all across the state from Lake Charles to Shreveport to Baton Rouge, DEQ officials said.
“It wasn’t a Baton Rouge situation yesterday,” Bergeron said about Wednesday. “We had similar weather across the state.”
Most of the exceedances were above the new standard but below the old one, Bergeron said. Without the lower standard, only one of the areas across the state would have been out, he said.
“The air didn’t get worse. The standard just got lower,” Bergeron said.
The five-parish area of East Baton Rouge, West Baton Rouge, Ascension, Iberville and Livingston, has been classified as “marginal,” which is the least severe of classifications and means the area has three years to come into compliance.
The ozone forecast from DEQ on Friday afternoon stated that light to moderate winds meant that air quality levels were high-moderate in the Baton Rouge, New Orleans and Shreveport areas.
The forecast called for clearing of the air Saturday and Sunday with more wind and the possibility of rain.
For daily updates on air quality by email, people can sign up for EnviroFlash on DEQ’s website at http://www.deq.louisiana.gov.