UPDATED: Unhealthy Air Quality Returns to Mon Valley with More of the Same Expected Thursday


UPDATE #2 (4:31 p.m. Wednesday, Nov. 22): The state Department of Environmental Protection on Wednesday afternoon declared Thursday, Nov. 23 a Code Orange Air Quality Action Day for particulate matter.


UPDATE #1 (2:40 p.m. Wednesday, Nov. 22): The Allegheny County Health Department issued the following message through its Allegheny Alerts system:


The Mon Valley Air Pollution Warning will continue through at least the end of tomorrow, November 24. A strong weather inversion with light winds will permit fine particle matter pollution (PM2.5) to build overnight into Thursday morning. The highest PM2.5 concentrations will come between 3 a.m. and 11 a.m., leading to overall average concentrations in the CODE ORANGE range in the Mon Valley. Because of these conditions, the Pennsylvania Department of Environmental Protection has declared tomorrow an Air Quality Action Day. The Air Quality Program will continue to monitor the situation and reassess conditions and provide more information to residents, as it becomes available. Young children, seniors, and those with respiratory problems, such as asthma, emphysema, and bronchitis, are especially vulnerable to the effects of air pollution and should limit outdoor activities during this time.


Foul air quality has returned to the Mon Valley this week with residents waking up Wednesday to surging concentrations of particulate matter and hydrogen sulfide, as well as a NowCast AQI of 164 indicating air quality reached a level the EPA classifies as unhealthy and which was, for a time, the very worst in the nation.


But the trouble started yesterday when concentrations of fine particulate matter (PM2.5) exceeded federal health-based standards at ACHD’s air quality monitor in Liberty Borough. Monitor data also showed levels of hydrogen sulfide (H2S) exceeded Pennsylvania’s 24-hour average standard.


As a reminder: H2S is a colorless gas recognizable by its rotten egg odor and the concentrations we see in the Mon Valley can cause irritation to the eyes, nose, or throat as well as headaches, poor memory, tiredness, and balance problems. It may also cause difficulty in breathing for some asthmatics, according to the Agency for Toxic Substances and Disease Registry.


Unfortunately, these abysmal air quality conditions are expected to persist today and tomorrow.


Yesterday the Allegheny County Health Department (ACHD) issued a Mon Valley Air Pollution Watch while the state Department of Environmental Protection (DEP) declared today a Code Orange Air Quality Action Day for particulate matter. By early Wednesday, ACHD upgraded the Watch to a Warning.


Here’s the message ACHD sent through its Allegheny Alerts system:


An Air Pollution Warning has been issued for the Mon Valley for today, November 23. The 24-hour PM2.5 standard for the Mon Valley has been exceeded at an official monitoring station in the Mon Valley.


Young children, seniors, and those with respiratory problems, such as asthma, emphysema, and bronchitis, are especially vulnerable to the effects of air pollution and should limit outdoor activities during this time.


Companies most significantly contributing to particulate pollution in the Mon Valley region are required to temporarily reduce particulate emissions.


As a reminder, Watches and Warnings are issued as part of the county’s Mon Valley Air Pollution Episode Rule, which was designed to reduce PM2.5 levels during prolonged periods of poor air quality.


Under the new rule, ACHD monitors weather forecasts and atmospheric conditions that could lead to an “episode” (i.e., when meteorological conditions are likely to contribute to unacceptable air pollution levels in the Mon Valley). A Watch is issued when these conditions are likely, and a Warning is issued when these conditions occur.


When ACHD issues a Warning - as it did this morning and for a span of four days last month – sources of PM2.5 emissions within a defined Mon Valley area subject to the new rule are required to follow approved mitigation plans to reduce their emissions of particulate matter. We have a great explainer with info on the rule and all the facilities subject to it. You can check that out here.


"We've heard from residents complaining of itchy eyes and throats and telling us that by early morning they had already needed tor each for their rescue inhalers," GASP Executive Director Patrick Campbell told the Tribune-Review Wednesday. "It's truly a shame how often residents in the Liberty-Clairton area are confronted with unhealthy air quality. People are really suffering today."


The GASP team is keeping an eye on the data and will keep you posted.





118 views0 comments