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About That Rotten Egg Odor Plaguing Your Neighborhood, What Causes It & How U.S. Steel Can Help

Editor’s Note: This blog was updated at 6:47 p.m. Nov. 19 to clarify the health impacts related to hydrogen sulfide.

For many in the Mon Valley, the first week of November was punctuated by the persisting odor of rotten eggs – an odor pungent enough to force local residents to shutter their windows and doors despite unseasonably warm and sunny weather.

The culprit, of course, was hydrogen sulfide (H2S for short) – a colorless, flammable, gas that’s long been an issue for communities adjacent to and downwind of industrial sources like U.S. Steel’s Clairton Coke Works and Edgar Thomson facility.

Other than the decidedly unpleasant odor, the higher hydrogen sulfide levels we see on occasion can induce tearing of the eyes and symptoms related to over-stimulation of the sense of smell, including headache, and nausea.

In fact, hydrogen sulfide is so unpleasant and common near certain industries that Pennsylvania has required H2S in the ambient air to be less than 0.005 parts per million (ppm), averaged over 24 hours. This standard is enforced locally by the Allegheny County Health Department (ACHD) Air Quality Program.

Yet, that standard was exceeded for seven straight days in early November. So far this year, the H2S standard has been exceeded 23 times at the Liberty air quality monitoring site according to preliminary ACHD data.

Those signed up to receive messages through Allegheny County’s Alert system may recall that ACHD issued a statement about that prolonged period of poor air quality. In it, health officials placed the lion’s share of the blame for the days-long subpar air quality on stagnant weather conditions and asked residents to do their part to mitigate air pollution. 

Absent from that message, however, was any mention of those elevated hydrogen sulfide concentrations or the exceedances of the state standard they spurred. Also missing was a plea to companies like U.S. Steel to do all it can to reduce its emissions during periods of weather expected to exacerbate air quality, creating a public health hazard. 

GASP made that call last week, imploring U.S. Steel to voluntarily dial back its production on days when Allegheny County grapples with inversions or other weather conditions expected to trap air pollutants closer to the ground.

This week, we’re renewing that call. 

“The polluters are the problem here,” GASP Executive Director Rachel Filippini said. “ACHD is making a good faith effort to combat these exceedances on several fronts. Not only has the air quality program committed to purchasing several new, mobile H2S monitors to be deployed throughout the county, they are also in the process of updating its coke oven regulations and have promised action on its woefully outdated episodic weather regulations.”

But she said it’s important to note that while regulations that would force industrial air polluters to reduce operations within 24 hours’ notice from the health department of a weather event expected to cause a public health hazard are sorely needed, they won’t be in place any time soon.

“We have to be realistic and understand the process: It can take as long as 18 months to bring a regulation from the first draft to enforceable rule,” Filippini said. “That’s why it’s so imperative that major H2S emitters like U.S. Steel step up and protect the surrounding community now.”

GASP senior staff attorney John Baillie agreed.

“Asking residents to curtail certain activities when air dispersion is poor might make an impact on levels of particle pollution, but there’s absolutely nothing we as individuals can do to affect levels of hydrogen sulfide,” he said. “But as the largest emitter of hydrogen sulfide in the county, U.S. Steel certainly could.”

GASP has said it before and will say it again: If U.S. Steel can reduce operations to accommodate market conditions, it can reduce operations to accommodate weather conditions. The company is simply choosing not to do so.

“Here in Pittsburgh, we grew up watching Mr. Rogers, so the notion of being a good neighbor is one that’s ingrained in so many,” Filippini said. “As a ‘Burgh-based company, one would think they’d have a vested interest in the health and welfare of residents in neighboring communities as well as its own employees.”

Despite one open letter and several subsequent calls to action, U.S. Steel has made no public comment addressing if, how, and when it would heed calls for it to be a more responsible corporate citizen and reduce operations during bouts of poor air dispersion.

And it’s well past time that it did. Allegheny County is no stranger to inversions. They happen here often. Local folks may recall that just last year, our holiday season was marred by eight days of unbearable air thanks to a major inversion. 

While often severe, some have even been deadly. While GASP was not around during the infamous 1948 Donora smog incident that killed 20 people and sickened thousands more, we were involved in the policy debates following an air pollution episode during November of 1975, to which an Environmental Protection Agency (EPA) study attributed 14 excess fatalities.

And yes, we pushed for updated episodic weather regulations back then, too. At the time, our members called on regulators to address what was (and is) a glaring omission: A curtailment plan for U.S. Steel.

In a 1976 press release GASP wrote: “U.S. Steel’s recalcitrance and (regulators’) inadequacy must not be permitted to persist to the next emergency in Allegheny County. All sources must submit signed curtailment plans and sources which do not comply must be prosecuted.”

So the question remains: How many more air pollution-related emergencies will Mon Valley residents need to endure?

It appears the answer can only come from one of two places – U.S. Steel or ACHD. For its part, ACHD appears to be trying to take strides to solve the problem while U.S. Steel has done nothing but fight the county at every turn when it comes to mitigating H2S emissions – most recently objecting to coke oven regulation updates the department believes will reduce fugitive and other emissions.

That’s why we are asking today for your help and your voice: We need to send a clear message to U.S. Steel that it must take action to voluntarily reduce operations when severe weather is expected to negatively impact air quality and public health. 

We encourage you to contact U.S. Steel to ask them to do just that. You can contact the company a couple of different ways:

  1. You can call U.S. Steel spokeswoman Meghan Cox at 412-433-6777 or email her at

  2. Email Clairton Coke Works plant manager Michael Rhoades at

  3. You can tag the company in a tweet – its Twitter handle is @U_S_Steel.

  4. More of an Instagram user? The company’s handle on that platform is @ussteelcorp.

We also encourage you to join GASP, Allegheny County Clean Air Now, Breathe Project, Clean Air Council, Clean Water Action, PennFuture, and residents at a virtual rally slated from 12:30 p.m. to 1:30 p.m. this Friday, Nov. 20 to speak out about this most recent bout of horrific air quality and demand accountability. You can get more information and RSVP here.

Editor’s Note: Stay tuned – we’re following this issue closely and will update the website with more information as it becomes available. Join us on Facebook, Instagram, and Twitter for immediate updates.

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