This week's steamy temperatures have many service agencies urging caution for public health and safety including the Indiana Department of Environmental Management.
The hot, humid conditions and still winds prompted IDEM to issue three Air Quality Action Days Monday through Wednesday this week, urging residents and businesses to take action to reduce their impacts on ozone creation.
IDEM spokesman Dan Goldblatt said the call to action does not contradict the state's overall reduction in air pollution.
"There is a difference between what IDEM does from a regulatory perspective (permit limits, engine and fuel standards, etc.) that help year round, but the things we can do to help on action days is important to address the rare days values are to be higher," Goldblatt said.
Wednesday marks the fifth Air Quality Action Day of the season, which runs from May through October.
Ozone is formed when air pollution caused by auto emissions and burning fossil fuels such as coal mix with nitrogen oxide and volatile organic compounds. The mixture is "cooked" by sunlight and creates ozone.
Ozone is a health issue for children, the elderly and those with pre-existing respiratory problems such as asthma. At times, ozone levels can be high enough to cause breathing problems for even the healthiest individuals.
"There's a lot that every person can do to reduce ozone," Goldblatt said.
With Northwest Indiana's power plants being coal-fired, reducing electricity use is a way to help reduce ozone on action days, Goldblatt said.
"At home, turn your air conditioner to 75 or higher and if you're not using something electronic, turn it off and unplug it," he said.
Reducing automobile use is another key to keeping ozone down. Goldblatt recommends walking, biking or using public transportation whenever possible.
"If you have to drive, combine trips and try not to idle for more than 30 seconds," he said. "If you run out to grab fast food, don't use the drive-through lane."
Waiting to do gasoline-powered lawn work until after 7 p.m. when the sun's ray are not as strong helps as well.
"Lawn mowers don't have the same emission controls as automobiles," Goldblatt said.
In 2012, Northwest Indiana logged 27 Air Quality Action Days, fueled by a string of record-high temperatures in the summer.
Last summer's weather conditions pushed LaPorte County's ozone levels past the federal threshold, meaning it no longer meets the federal Clean Air Act for ozone pollution.
Counties that are deemed out of compliance for the ozone standard have tight restrictions on new construction for facilities that emit regulated air pollutants. They also participate in the state's Clean Air Car Check program, which periodically tests auto emissions.