LANSING — State Representative Stephanie Chang (D-Detroit) introduced legislation today to address air pollution that is made worse during a weather condition known as thermal inversion. This kind of air pollution is a particular problem in Southwest Detroit, which is part of House District 6 that Chang serves.

Thermal inversion is a weather condition during which a layer of warm air overlies a layer of cooler air near the ground and acts like a lid, limiting vertical mixing and thereby trapping pollutants near the ground.

“I became aware of thermal inversion because air quality is a major concern in Southwest Detroit, which is home to many major sources of pollution, including the Marathon refinery. This has led to major health concerns like asthma, COPD, and various forms of cancer,” said Chang. “Even when companies are operating normally, during thermal inversion conditions, air pollution becomes an even bigger problem for residents because pollutants do not disperse the way they normally would. That is why we need to address this problem.”  

The first bill in Chang’s package would require the Michigan Department of Environmental Quality (MDEQ) to declare an air quality action day for a geographic area in Michigan when it has forecasted that the air quality index or particulate matter (PM 2.5) sub-index are in the “moderate” category or worse — meaning that the air pollution would be “unhealthy for sensitive groups” of residents, such as children, senior citizens and people already suffering from illnesses. An air quality action day means that MDEQ gives the public advance notice of the air quality anticipated for a certain day.

The bill also creates a new “winter thermal inversion action day” if there is a thermal inversion forecasted during the winter months. MDEQ would also be required to convene a workgroup to study thermal inversions and develop further actions to be taken to address air quality as related to thermal inversions. The workgroup would include public health experts, air quality experts, representatives of environmental protection organizations, and residents of areas in Michigan with high levels of air pollution.

Chang’s second bill requires each company applying for a new or renewal air quality permit to include a plan for the appropriate reduction of emissions during winter thermal inversion action days.

Other states such as Utah and Colorado already have policies to address thermal inversion.

“Acknowledging the very real and adverse air pollution effects of thermal inversions is an important step to improving air quality in the Detroit area and around the state,” said Stephanie Karisny, from the Great Lakes Environmental Law Center.

“My bills are important especially now, when Marathon Refinery’s application for a new permit could lead to greater air pollution,” said Chang. “The MDEQ is holding hearings on that permit request now. I remain opposed to Marathon’s request. I hope that my legislation will win my colleagues’ support so that we will have measures in place to mitigate both the current heavy air pollution, and any increased pollution, for the residents of Southwest Detroit, and any other Michigan community dealing with air pollution.”