The ArkLaTex typically has clean air, but air quality can worsen this time of year when high pressure keeps pollutants from dispersing.
Tommy Perryman, an environmental scientist for the Louisiana Department of Environmental Quality, said high pressure ridges that build during the summertime trap pollutants and increase air quality index values in the ArkLaTex.
"This time of year you get more pollutants because of the high pressure,” Perryman said. “The air stagnates under the high pressure. So you don't have the cleaning of the air, the circulation of the winds."
Under ridges of high pressure, air sinks and winds are light. That can trap pollutants, like Volatile Organic Compounds (VOCs). VOCs are gases emitted by subtances like paints, lacquers and pesticides.
The ArkLaTex typically has good air quality compared to nearby cities like Dallas and Little Rock. That’s due to the ArkLaTex’s relatively light traffic, less industry and a less concentrated population.
However, winds can transfer pollutants from nearby cities to the ArkLaTex. Earlier this summer, air quality alerts were issued for east Texas counties where winds had carried pollutants from Dallas.
The Environmental Protection Agency recently changed the Air Quality Index slightly to make requirements stricter. Even on the more stringent scale, the ArkLaTex usually falls in the “good” or “moderate” categories.
Air Quality Alerts are issued when the index values in an area increase into the “orange” category. Healthy adults may not notice a change in the air, but sensitive groups may be affected by the pollutants. People with asthma may cough or wheeze. Children and the elderly may also notice a difference.
Air quality is normally worse in the morning and afternoon than in the evening.
“The direct sun kind of cooks the VOCs in the air, so it’s best to go outside and run errands after 6:00 in the evening,” Perryman said.
The Louisiana Department of Environmental Quality’s air quality monitoring sites are in downtown Shreveport and in Dixie.
Click here for hourly air quality data for your location.