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Writer's pictureGroup Against Smog & Pollution

Join GASP in Telling ACHD: Enough with the Rotten Egg Odor—It’s Time to Meet the H2S Standard!

Updated: Dec 23, 2022


Girl covers nose with hand showing that something stinks isolated on gray background


Sad but true: Waking up in the middle of the night to the odor of rotten eggs isn’t that uncommon in Allegheny County—especially downwind of the Mon Valley.


For those who aren’t aware: That tell-tale rotten egg smell is characteristic of malodorous hydrogen sulfide (more commonly referred to as H2S) and is perceptible by most people event at very low concentrations.


The H2S odor is so unpleasant and common that Allegheny County has required an ambient limit of .005 parts per million (ppm) averaged over 24 hours. Unfortunately, the standard has been repeatedly violated at the air pollution monitor in Liberty (located in the Mon Valley).

Here’s a breakdown of the number of violations of the .005 ppm standard by year:

  1. 2018: 35

  2. 2017: 59

  3. 2016: 41

  4. 2015: 87

  5. 2014: 49

  6. 2013: 28

  7. 2012: 65

Please add your voice to the hundreds of Allegheny County residents who’ve said “enough is enough” and sign our petition today.GASP thinks we deserve better, and that the folks charged with ensuring compliance—the Allegheny County Health Department—can and should do better. That’s why we’re collecting signatures for our petition calling on ACHD to do what it takes to achieve the H2S standard.


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