Allegheny County is drafting a rule that would require U.S. Steel to take action during high-pollution days
In mid-December, the state of Pennsylvania issued a warning to residents in the Mon Valley: The forecast wasn’t about the snow but about the poor quality of its air during a temperature inversion. This follows a streak of poor air quality last winter, and more recently. One day in November, air pollution in the Mon Valley reached 129 micrograms of fine particulate matter. The 24-hour standard set by the Pennsylvania Department of Environmental Protection [DEP] is 35 micrograms per cubic centimeter (µg/m3). This level is considered especially unhealthy for sensitive groups like children, the elderly and people with asthma.
The air also exceeded the state standard for hydrogen sulfide for seven days straight during a temperature inversion in early November.