MI HB4256

Requires the Department of Natural Resources to make air quality index (AQI) forecasts at least 24 hours in advance and publicize them on its website and through other means, using accurate procedures considering meteorology, topography, and data availability.

Mandates the department declare "action days" for geographic areas when AQI or PM 2.5 subindex is forecast to reach moderate category or worse, and designate action days caused by thermal inversions during November through March as "winter thermal inversion action days."

Requires the department to review its AQI program within 180 days and may revise ozone or PM 2.5 standards, voluntary pollution prevention measures, or further restrict industry emissions of PM 2.5 and ozone-contributing emissions during thermal inversions.

Directs the department director to convene a workgroup including public health experts, air quality experts, environmental organizations, and residents from high-pollution areas to study thermal inversions and recommend air quality and public health actions.

Workgroup must submit findings and recommendations to the department director and relevant legislative committees within one year of the act's effective date; workgroup dissolves 90 days after the report is due.