Pittsburgh Air quality today

How does Pittsburgh compare with other US cities?

The Lung Association's 2026 report covers the Pittsburgh-Weirton-Steubenville metro area, using 2022 to 2024 data ^[1]. It got an F for ozone smog, an F for short-term particle pollution and a failing grade for year-round particle pollution ^[1].

The area ranked 11th worst in the country for short-term particle spikes, 16th worst for year-round particle pollution and 63rd worst for ozone ^[1]. Allegheny County averaged 9.3 days a year with unhealthy particle spikes, down from 10.8 in the previous report ^[1]. The area's year-round level was its best ever, but Allegheny County still failed, with levels above the federal standard ^[1].

What is PM2.5, and why does it matter?

PM2.5 means fine particles 2.5 micrometers across or smaller ^[10]. An average human hair is about 70 micrometers wide ^[10]. Among particles, PM2.5 poses the greatest risk to health ^[10]. Many fine particles form in the air from gases such as sulfur dioxide, given off by power plants, industry and vehicles ^[10].

Allegheny County's health department says particle pollution can cause coughing, wheezing and asthma attacks ^[8]. It is also linked to heart attacks, strokes and early death in people with heart or lung disease ^[8].

Why do the river valleys trap pollution?

An inversion happens when a warm layer of air sits above colder air near the ground ^[2]. Pollution that would normally blow away gets trapped close to the ground ^[2].

The Mon Valley is a string of towns along the Monongahela River, about 20 miles south of Pittsburgh ^[2]. Like all valleys, it is prone to stagnant air, because the hills around it hem it in ^[2]. In an episode reported in January 2020, starting on December 21, the region's daily particle levels broke federal safety standards for six days in a row ^[2]. At one point, a monitor near the Clairton Coke Works recorded the worst air quality in the US ^[2].

What role does the Clairton Coke Works play?

U.S. Steel's Clairton Coke Works is one of the region's main sources of air pollution ^[2]. It turns coal into coke for steelmaking by cooking it at very high temperatures ^[2]. The county health department says a 2022 study found the plant is a significant source of hydrogen sulfide gas ^[3].

By March 2019, after a December fire damaged pollution controls at Clairton, monitors near the Mon Valley plants had recorded several sulfur dioxide spikes above federal standards ^[5]. Sulfur dioxide can make breathing problems worse ^[5]. In January 2026, a control room breakdown at the plant led to raised hydrogen sulfide, sulfur dioxide and PM2.5 readings at the nearby Liberty monitor, during a weak inversion ^[6].

How did Pittsburgh's smoke history shape clean air laws?

Pittsburgh's smoke and dust were once so thick that streetlights had to be lit at midday ^[9]. Allegheny County adopted its first air pollution control law in 1949 ^[9].

In 1948, an inversion settled over Donora, a mill town in a river valley south of Pittsburgh, and trapped pollution for five days ^[9]. Twenty people died and 6,000 of the town's 14,000 people were sickened ^[9]. The disaster set off efforts to control air pollution and helped spur the federal Clean Air Act ^{[9] [2]}. Richard Nixon signed the Clean Air Act of 1970 ^[9].

What is being done about Pittsburgh's air?

In September 2021, the Allegheny County Health Department added the Mon Valley Air Pollution Episode Rule to its air regulations ^[3]. It requires certain plants, including the Clairton Coke Works, to have a plan to cut particle emissions when an air quality warning is declared for the Mon Valley ^[3]. When high PM2.5 is forecast, the county issues a watch, and the main polluters must have equipment and staff ready to act ^[7]. If the 24-hour PM2.5 standard is broken and likely to stay broken, a warning orders them to cut polluting activity ^[8].

The county also fines the Clairton plant. In March 2022 it announced a penalty of 4,570,500 dollars for 831 violations between January 2020 and March 2022, when hot coke was unloaded without filtering its emissions ^[4]. A December 2023 order for hydrogen sulfide violations carried a penalty of 2,202,825 dollars ^[3]. U.S. Steel said it disagreed with many points in the 2022 order ^[4].

How to protect yourself in Pittsburgh

Check the Air Quality Index, or AQI, a color scale that runs from green for good to maroon for hazardous ^[11]. At orange, people in sensitive groups may feel health effects, and at red some members of the general public may too ^[11]. Allegheny County lets residents sign up for Allegheny Alerts to get local air quality updates ^[8].

On days with a Code Red alert for fine particles, the county advises people with breathing conditions, older adults, children, teens and people active outdoors to avoid long or intense outdoor activity ^[7]. Others should cut back and take more breaks ^[7]. On Code Orange days, people with asthma should follow their asthma action plan and keep quick-relief medicine on hand ^[7].

When wildfire smoke arrives, keep windows and doors closed, as US EPA advises ^[12]. Portable air cleaners and high-efficiency furnace or air conditioning filters, such as those rated MERV 13, can remove particles indoors ^[12]. Avoid making more particles inside, such as from cooking, smoking or burning candles ^[12].