Several factors, including wind patterns over Lake Michigan that push ozone back “downstream” toward Michigan City and LaPorte County, help to explain why it has Indiana’s worst smog, experts say.
“It’s a combination of dense population, industries, the power plants that are there, the meteorology of the region and the lake,” said Janet McCabe, director of the Environmental Resilience Institute at Indiana University, and a former Indiana and EPA top air quality regulator.
In fact, three shoreline communities - Gary, Ogden Dunes and Michigan City - all have Indiana’s worst ground-level ozone, with readings getting worse going east, state records show.
“I don’t buy that Chicago-only theory,” said Gabriel Filippelli, an Earth Sciences professor and director of IUPUI’s Center for Urban Health. “Sure, you can get ozone that’s brought upstream (from Illinois and Wisconsin). I would tend not to look further than Northwest Indiana.”
It has all the local sources contributing -- factories, power plants, trains, trucks, cities, he said.
Ozone is produced when pollutants from cars, trucks, buses, industrial smoke stacks, gas stations, paints, lawn mowers and cleaning solvents bake in the summer sun and react.
Generally, high ozone levels occur on days with high temperatures and low wind more often than on days with moderate temperatures.
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