For the third year in a row, Louisville isn’t going to meet federal standards for ground-level ozone pollution, according to the Air Pollution Control District.
Mostly, the air quality in Louisville is improving, but the city is still struggling to meet federal standards for ground-level ozone (that’s ground-level as opposed to the stuff in the stratosphere that helps protect the planet from harmful ultraviolet rays).
The city is currently at about 75 parts per billion, which is about five billion parts over the standard set by the Environmental Protection Agency, said Michelle King with the Air Pollution Control District.
High levels of ozone can trigger respiratory problems, especially in children and older adults. Ozone constricts airways, causing coughing, throat and chest pain. It can increase the risks of asthma, bronchitis and infant mortality, according to the American Lung Association.
Ground-level ozone forms when volatile organic compounds (VOCs) and oxides of nitrogen (NOx) combine in the presence of sunlight. Both are common by-products of combustion engines and industrial facilities.
“When you’re at the pump and you smell the gas? That’s a really good example of [VOCs],” King said.
The city usually issues air quality alerts when ozone levels are high. This year, Louisville experienced 11 of those high-ozone days, while last year it had only six, according to the Air Pollution Control District.
“This is not so much a steady line because the weather plays a big role in this so you have a hot summer, you have a lot of ozone,” King said. “You might have the very same emissions profile the next summer, but it will be a much cooler, wetter summer and have very little ozone problems.”
All of this year’s high-ozone days were between June and September, which makes sense because ozone usually reaches unhealthy levels on hot, sunny days.
As the climate warms over the coming decades, Louisville will see the number of warm days increase, thus raising the ozone risk.