Only two counties in Indiana require emissions tests for some passenger cars — Lake and Porter. State lawmakers have long blamed smog from Chicago and interstate travel for this. But how smog forms around Lake Michigan is much more complicated.
What is smog and why do some residents have to get their cars tested?
Smog — or ozone pollution — forms from the combination of sunlight and pollution from things like cars and industrial plants. Smog can make it more difficult to breathe and aggravate lung and heart conditions.
Lake and Porter counties don't meet the national air quality standard for ozone. One way to reduce ozone pollution is requiring people get their cars tested for emissions in order to be licensed.
The testing is free for drivers (aside from a convenience fee charged at some testing stations), but cars that fail the test could need expensive upgrades to comply.
How does Lake Michigan affect ozone pollution?
Zac Adelman is the executive director of the Lake Michigan Air Directors Consortium (LADCO) — a nonprofit that helps states in the Great Lakes region understand and address air pollution.
Adelman said weather and other meteorological conditions along Lake Michigan make its shoreline a hotbed for smog.
He said we tend to see the most ozone when the wind blows up from cities and industries in the south to rural areas up north that don’t pollute much at all — like Door County, Wisconsin.
“These emissions react and form ozone over the lake, and then this plume of ozone really hits these areas along the lakeshore in northern Wisconsin and coastal Michigan," Adelman said.
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Why no one area is to blame for smog
Adelman said ozone is a regional problem that needs regional solutions. He said ozone can form from sources of pollution across a wide area and it doesn’t stay put.
He said that's one reason why the Environmental Protection Agency often requires things like emissions testing in areas that significantly contribute to smog — like heavy industry in northwest Indiana. Adelman said northwest Indiana is one of the reasons why the Chicago area doesn't meet the ozone standard.
“So if we're going to comply with the ozone standard in this region, it has to be a regional effort," Adelman said.
Lawmakers passed a bill this year that aims to find ways to no longer require car emissions testing in Lake and Porter counties — either by reducing pollution or seeking "regulatory relief” from the federal government.
If the state of Indiana does stop emissions testing in Lake and Porter counties without reducing emissions, the EPA could choose to hold back federal funding for highways in the state.
Rebecca is our energy and environment reporter. Contact her at rthiele@iu.edu or on Signal at IPBenvironment.01. Follow her on Twitter at @beckythiele.