Air quality in the Baton Rouge and Hammond metro areas has received failing grades for smog and fine particle pollution in a new three-year study, while New Orleans dropped in the national rankings despite faring better than those neighboring cities.
The American Lung Association's for 2026 revealed a mixed picture for Louisiana air quality based on those two major pollutants between 2022 and 2024.
In northern Louisiana, the Monroe-Ruston and Shreveport-Bossier City metro areas were rated among the cleanest in the nation for ground-level ozone -- more commonly known as smog -- and short-term particulate pollution, respectively. Though most other parts of the state remained in compliance, many saw pollution rankings slip as they fell behind other states with improving air.
For Baton Rouge and Hammond, the Lung Association's failing grade for ozone — due to Baton Rouge-area parishes — suggest non-compliance with federal air quality standards, the nonprofit says.
"Unfortunately, too many people in the Baton Rouge and New Orleans metro area are living with unhealthy levels of ozone and particle pollution," said Eric Weinzettle, the Lung Association's director of advocacy. "This air pollution is causing kids to have asthma attacks, contributing to chronic health conditions, and making people who work outdoors sick."
The Lung Association relied on the U.S. Environmental Protection Agency's Air Quality Index ratings for ozone, 24-hour fine particulate pollution and annual fine particulate pollution. Those ratings rely on data from the state air monitoring network.
EPA has scrutinized ozone and particulates for decades due to their broad presence across the nation and serious health impacts.
Especially harmful to children, older adults and people with asthma, ozone can cause breathing problems, may be a cause of asthma and can lead to premature death, the EPA says.
Chemical plants along the Mississippi River.
David Grunfeld / The Advocate
Fine particulates are microscopic solid or liquid particles that can embed in the lungs and enter the bloodstream. They can cause breathing problems but also raise the risk of high blood pressure, stroke and heart disease.
For 2022-2024, East Baton Rouge, Iberville and West Baton Rouge parishes all received an "F" for ozone from the Lung Association.
West Baton Rouge also received a failing grade for annual particulate levels, with a level nearly 1.1% higher than the federal standard. Under the association's scoring, the lowest parish scores brought down the entire metro areas.
The combined metropolitan statistical areas of Baton Rouge and Hammond, which the nonprofit lumped in with Baton Rouge, worsened by six spots nationally over last year, falling from 32nd to 26th worst for ozone.
To exclude or not
The New Orleans metro area ranked 100th worst for ozone nationally, a nearly 7.5% drop from last year, but it still a received a "C." The area saw greater slips in national rankings for short-term and annual particulate pollution but still received strong grades, the association says.
The combined ozone grade for New Orleans and Hammond was based on St. John the Baptist Parish, which has the lowest grade in the two regions. State ozone data weren't available in Orleans or Tangipahoa parishes.
Adding to the mixed picture, Shreveport-Bossier City ranked among the best in the nation for short-term particulate pollution, receiving an "A," but was among the worst for annual particulate levels. Particulates in Caddo Parish were 7.7% higher than the annual federal standard for the three-year period, giving the area a failing grade.
The state Department of Environmental Quality, which operates state air monitors, has previously questioned how the Lung Association analyzes air data and declined to comment on its report.
Traffic stacks up on northbound Airline Highway at Goodwood Boulevard, Wednesday, September 17, 2025, in Baton Rouge, La.
STAFF PHOTO BY HILARY SCHEINUK
The EPA allows states to exclude days with bad air from natural events for calculations that can bring regulatory consequences. In recent years, DEQ has convinced EPA to exclude high particulate levels in West Baton Rouge for days in 2022 and 2023 due to Saharan dust storms and Canadian wildfires.
The EPA method also shaves off the three worst days of pollution in a year for a more evened-out picture. The Lung Association report also relies on an annual particulate standard that the Trump administration is reconsidering to boost oil production and manufacturing.
Arguing that people breathe bad air whether regulators count them or not, the Lung Association applies every bad air day under AQI's standards, weights them based on severity and averages them over three years.
Air toxics not included
The report, however, doesn't look at many other pollutants, including air toxics from industries and other sources that contribute to risk for cancer and other ailments.
Ozone forms when compounds released from fossil fuel burning in cars, power plants, industrial facilities and other sources react with sunlight.
Going back to the early '90s, the Baton Rouge metro area has struggled periodically with being in "non-attainment" for ozone, forcing increased business costs and regulatory efforts.
In March 2017, EPA declared the area in attainment, but the Lung Association says its "F" grade for the Baton Rouge region correlates with non-attainment.
Iberville had Louisiana's worst rating for ozone. The parish had the most bad air days at 29 over three years and had the highest weighted, three-year average at 10.2 days per year.
Preliminary data from the Baton Rouge Clean Air Coalition show seven of nine DEQ air monitors in the Baton Rouge area were at or below the federal ozone standard between 2022 and 2024.
But state monitors in West Baton Rouge and Iberville had average ozone concentrations 1.5% to nearly 6% above the federal limit for 2022 to 2024.
DEQ officials said they believed local and international wildfires in 2022 and 2023 contributed to those measurements and tried to have EPA exclude those high days.
Jason Meyers, administrator for DEQ's Air Planning and Assessment Division, said EPA declined to review DEQ's proposal because it did not meet the requirements.
Desiree Lemoine, campaign manager for Industry Makes, which advocates for Louisiana manufacturing, pointed out that ozone and particulates can come from heavy traffic and agricultural burning.
She noted that Baton Rouge and Lake Charles, which also has a large industrial base, are near busy interstate highways.
"Cars sitting in traffic on sunny days cause ozone," Lemoine said.
She suggested the association's findings could be read positively because most metro areas had passing grades.
"I think this is something Louisiana should celebrate, considering the reputation we have outside of our state's lines," Lemoine said.