Wildfire smoke from Canada and Minnesota pouring over Pennsylvania spurred a code red air quality alert Thursday, July 16, according to the state Department of Environmental Protection.

The department said the smoke is creating air quality code red concentrations of PM2.5, which means fine inhalable particles of particulate matter with diameters of 2.5 micrometers and smaller unhealthy to all groups may be in the air.

The particulate matter forms from a mixture of solid particles from the wildfires and liquid droplets in the air, according to the U.S. Environmental Protection Agency. It explained relative to 2.5 micrometers, the average human hair is about 70 micrometers in diameter, which means the hair is about 30 times larger than the finest particles in the air.

The agency said fine particles less than 2.5 micrometers in diameter pose the greatest risk to health as the particles are inhaled deep into the lungs, sometimes entering the bloodstream.

The state DEP recommends limiting outdoor activities and to consider moving outdoor activities inside. Residents can also help reduce pollution by avoiding burning and gas-powered equipment.

The department recommends checking airnow.gov to view the current air quality.

The air quality is expected to increase slightly Friday into code orange but will still include the PM2.5 rating, according to airnow.gov. The conditions could prove harmful to certain groups such as people with heart or lung disease, older adults, children and teens.