The National Weather Service has issued an Air Quality Alert through midnight Saturday for Lorain, Cuyahoga, Lake, Geauga, Ashtabula, Summit and Portage counties.
It means air quality levels will be unhealthy for sensitive groups, which include children, the elderly and people with breathing difficulties.
The advisory is due to ground-level ozone.
Ground-level ozone is a colorless gas that forms just above the earth’s surface that is produced when pollutants react in sunlight and stagnant air.
The NWS advises you to limit your time outside, wait to mow the lawn and refill your tank after sunset.