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UPDATED: Mon Valley Experiences 2 More Air Quality Exceedances Wednesday – First of 2021 For PM2.5

Updated: Mar 25

The values in red are indicative of exceedances of the state H2S standard of 0.005 ppm.

Editor’s Note: This story was updated at 1:46 p.m. Thursday, March 11 to include information from a press release issued by residents of the Mon Valley and Clean Water Action.

It probably won’t come as a surprise to our friends in the Mon Valley who suffered through what was at one point the worst air quality in the nation yesterday: Allegheny County experienced more air quality exceedances Wednesday – this time because of high levels of hydrogen sulfide and fine particulate matter (PM2.5).

For the third straight day Wednesday, preliminary data show concentrations of hydrogen sulfide (H2S) at Allegheny County Health Department’s Liberty air quality monitor exceeded the state’s 24-hour standard with an average concentration of 0.008 ppm. The Pennsylvania limit is 0.005 ppm.

That makes seven H2S exceedances so far in Allegheny County – four at the Liberty monitor and three more at North Braddock.

But that’s not all: For the first time this year concentrations of PM2.5 exceeded the federal health-based standard for ambient air. Preliminary data show the 24-hour average PM2.5 concentration at the Liberty monitor Wednesday was 44.6 ug/m3. The standard is 35 ug/m3.

Despite the exceedance of this health-based standard – and a health department air dispersion report Tuesday that predicted a moderate to strong surface inversion Wednesday – the public received no heads up from Allegheny County, which regularly communicates to residents various hazards through its Alerts system.

“This exceedance underscores the need for strong episodic weather regulations and better communications by the ACHD to let residents know when air is unhealthy,” GASP Executive Director Rachel Filippini said. 

For those who might not be following the issue: ACHD has for the last year been crafting regulations that would help curtail industry emissions when short-term weather events are expected to exacerbate poor air quality. It’s something GASP has advocated for not only in the past year, but over the past several decades.

“We’ll say it as many times as we need to in order to get these regs passed: ACHD badly needs an emission-reduction plan in place that could be implemented within 24 hours of notice that a public health hazard exists,” she said. 

Then last month, the Air Advisory Committee voted to table the regulations, sending the draft back to the regulation subcommittee for more specifics. 

Filippini, who serves on the committee, stressed that while there was merit in having one more discussion to hash out details, what isn’t acceptable is letting the regulations languish in meeting after meeting.

For inquiring minds who want to know: The next regulation subcommittee is scheduled to meet on March 23 – we’ll share the agenda and details on how to join the meeting as soon as that information is available.

“In the meantime, there’s nothing preventing ACHD from warning folks when air quality will be in the orange and red through their social media channels and the Alert system,” Filippini said.  

Meanwhile, residents in the Mon Valley in a press release Thursday afternoon expressed their frustration with ongoing poor air quality and demanded action from U.S. Steel (the largest pollution source in the Mon Valley) and Allegheny County officials.

“When we have bad air days, we’re limited like prisoners in our homes,” Cindy Meckel, a Glassport resident with Valley Clean Air Now, said. “This has to stop.”

Clairton resident Jacqueline Mills sent an email yesterday to County Executive Rich Fitzgerald which read in part:

“As a resident and grandmother in Clairton I am always concerned about the air and its effects on my 6 grandchildren. There have been so many days over the previous summers that they couldn’t play outside because of air quality! As adults we know the importance of outdoor play for growing children. Please help our city improve the air quality for future generations.”

PA Director of Clean Water Action Myron Arnowitt said Mon Valley residents are looking for leadership in Allegheny – whether in industry or government – to ensure the public’s health is protected.

“We need to stop pretending this problem has been solved, and take action that will have an impact on the kind of dangerous levels of pollution we’re seeing this week,” he said.

GASP joins Clean Water Action in reminding residents that when air quality is at unhealthy levels that they should avoid time outdoors. EPA has identified especially vulnerable groups as children, seniors, and people with a respiratory or heart condition. In the Mon Valley this is roughly half the population.

To sign up for Allegheny Alerts visit:

 We graphed the data for those who’d like to take a deeper dive:

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