Pennsylvania's Department of Environmental Protection is forecasting Thursday to be a Code Orange Air Quality Action Day for the Liberty-Clairton area. A higher than normal level of fine particulate matter is expected.
"Young children, the elderly, those with respiratory problems will be especially vulnerable," said DEP spokesperson Beth Rementer.
Thursday's predicted poor air quality is due to an expected temperature inversion, which traps fine particulate matter close to the ground and causes smoggy conditions. Fine particulate matter comes largely from industrial processes and fossil fuel combustion.
The Allegheny County Health Department plans to propose new regulations that would require industrial polluters, such as U.S. Steel, to limit emissions during weather-related pollution days. Department interim director Ronald Sugar has said those will be in place by the end of 2020.