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A Resident's Guide to Allegheny County's Mon Valley Air Pollution Episode Rule (and the Facilities Subject to it)

Air quality matters are rarely simple. Not the data. Not the regulations. Not the standards. It’s generally complex stuff. So when something new like the Mon Valley Air Pollution Episode Rule goes into effect, your friendly neighborhood watchdogs here at GASP try to remember that maybe a little plain-language FAQ might be helpful to better understand this stuff (and how it impacts you and your health).


Because the mitigation plans submitted by the facilities subject to the Mon Valley Air Pollution Rules have been in the news recently, we thought now might be the *perfect* time for a little primer on the regs.


Here’s what you need to know:

What's the new Mon Valley Air Pollution Episode Rule all about anyway?

The Mon Valley Episode Rule is an addition to the local Air Pollution Control Regulations that was signed into law in September 2021 by Allegheny County Executive Rich Fitzgerald. 


Its purpose? To develop and implement a system to respond to weather-related inversions in the Mon Valley, which can result in episodes of high levels of particulate matter pollution (PM2.5) – something GASP has been pushing for since the 1970s. No, really. For decades.


But back to the rule: Under the new regs, Allegheny County Health Department air quality staff monitors pollution forecasts for conditions that could lead to an “episode.” Translation: When meteorological conditions are likely to contribute to unacceptable air pollution levels in the Mon Valley.


When this happens, sources within the defined Mon Valley area that are subject to the new rule are required to follow approved mitigation plans to reduce their emissions of PM2.5 and PM10 – otherwise known as fine and coarse particulate matter. 


During these conditions, ACHD may issue either a Mon Valley Air Pollution Watch or a Mon Valley Air Pollution Warning.


What’s the difference between a Mon Valley Air Pollution Watch and a Mon Valley Air Pollution Warning?

Great question:


A Mon Valley Air Pollution Watch is issued when weather conditions are forecast to cause a high concentration of particulate pollution in the Mon Valley. During the “Watch” phase, facilities like U.S. Steel’s Clairton Coke Works must conduct basic checks to ensure equipment is in good working order and that they have adequate staff to take actions required under the “Warning” phase. 

A Mon Valley Air Pollution Watch is issued when weather conditions are forecast to cause a high concentration of particulate pollution in the Mon Valley. During the “Watch” phase, facilities like U.S. Steel’s Clairton Coke Works must conduct basic checks to ensure equipment is in good working order and that they have adequate staff to take actions required under the “Warning” phase. 

A Mon Valley Air Pollution Warning is issued when levels of particulate pollution exceeds federal health-based standards AND those conditions are expected to continue for 24 hours. Once a “Warning” is issued, facilities must undertake the actions listed in the mitigation plans they filed with ACHD. The specific actions are catered to each facility and approved on a case-by-case basis.

P.S.: The “defined Mon Valley area” is composed of the following communities: Braddock, Braddock Hills, Chalfant, Clairton, Dravosburg, Duquesne, East McKeesport, East Pittsburgh, Elizabeth Borough, Elizabeth Township, Forest Hills, Forward, Glassport, Jefferson Hills, Liberty, Lincoln, McKeesport, Munhall, North Braddock, North Versailles, Port Vue, Rankin, Swissvale, Turtle Creek, Versailles, Wall, West Elizabeth, West Mifflin, White Oak, Wilkins, Wilmerding, and Whitaker.

Which facilities are subject to the Mon Valley Air Pollution Episode Rule... and why?

The regulation requires air pollution mitigation plans from facilities in a defined Mon Valley area producing more than 6.5 tons of pm2.5 annually and/or more than 10 tons of pm10 annually. So far, there are 17 facilities within those 32 affected communities that are currently subject to the new rules. 


These are the facilities subject to the new rule that have submitted mitigation plans to the Allegheny County Health Department:

Final Plan Submitted
Mitigation Plans
Clairton Slag, dba RiverLift Industries
West Elizabeth
CP Industries
Dura-Bond Coating
Eastman Chemical Resins
Jefferson Hills
ELG Metals
Kelly Run Sanitation
Keywell Metals
West Mifflin
Lafarge Corp.
West Mifflin
Magnus Products (formerly operated by Braddock Recovery)
Mid-Continent Coal & Coke Co.
NCP Carbon
Jefferson Hills
TMS International (Clairton Coke Works)
TMS International (U.S. Steel Edgar Thomson Plant)
TMS International West Mifflin
West Mifflin
U. S. Steel Mon Valley Works – Clairton Plant
U. S. Steel Mon Valley Works – Edgar Thompson Plant
U.S. Steel Irvin Plant
West Mifflin

But what's up with those mitigation plans? What are the requirements?

Now that we know what the Mon Valley Air Pollution Episode is and what facilities are subject to them, it’s time to put the spotlight on those mitigation plans and what kinds of emissions reductions are included in them.


If you haven’t visited it yet, check out the Mon Valley Air Pollution Episode web page that ACHD developed. It includes information and resources for both residents and regulated entities. One of the resources posted to the site is a guidance document designed to help impacted facilities develop appropriate mitigation plans. 

The document lays out what information facilities subject to the Mon Valley Air Pollution Episode Rule must include as part of their Watch plans:


  • List all equipment and/or processes that emit PM2.5/PM10.

  • For each of those sources, briefly explain how it will be evaluated to ensure proper operation and maintenance during the watch phase.


The Air Quality Program also provided suggested elements facilities could implement as part of their Watch plans. They included:


Actions related to staffing: 


  • That the facilities review procedures with employees to ensure all equipment is “properly operating in a way to minimize emissions.”

  • That facilities schedule additional on-call employees for upcoming shifts to ensure adequate staffing.

  • That facilities conduct shift meetings to tell employees to “prioritize the environmental impact of their operations to reduce emissions.”


Actions related to equipment:


  • That facilities inspect equipment that have the potential to increase emissions of particulate matter.

  • That facilities implement improved operation and maintenance practices beyond the standard operating procedure.

  • That mobile sources operating on-site follow idling guidelines set forth by the Pennsylvania Department of Environmental Protection.

  • Conduct maintenance on all pollution-control equipment.


ACHD also details what facilities subject to the Mon Valley Air Pollution Episode Rule must include as part of their Warning plans:


  • List all equipment and/or processes that emit PM2.5/PM10 and list for each of those all available methods to reduce particulate pollution.

  • Describe each method and explain which of the available methods of particulate pollution reduction is feasible and what is not feasible.

  • Provide justification for why they deemed any emissions-reductions methods as unfeasible.

  • Include the percentage of potential PM2.5/PM10 reduction for each method found to be feasible.


The document notes that the reduction activities specified in the Warning phase must last the length of the episode, which ACHD indicates “historically has been four days.” It was also clear: Facilities MUST show their calculations and information related to their average daily emissions from 2017-2020.


The Air Quality Program also provided suggested elements facilities could implement as part of their Warning plans. Recommended activities included:


  • Reducing production by a certain percentage or rate from normal operating conditions.

  • Reducing diesel usage.

  • Bringing in additional employees to ensure proper maintenance and operation of equipment that emits particulate matter.

  • Delay production and/or non-essential activities to a future day when a mitigation plan is not needed.

  • Modify work practices to decrease emissions (i.e.: slowing material handing, fully or partially enclosing material movement and work activities that produce dust, etc.)

  • Stop or decrease unnecessary transportation activities and reduce speed.

  • Wet roadways to ensure dust mitigation.

How does ACHD evaluate Mon Valley Air Pollution Mitigation Plans?

The natural follow-up question after reading about all those requirements is, “So, how does the Allegheny County Health Department actually evaluate those bad boys?” Fortunately, the Mon Valley Air Pollution Episode page includes a document that lays out all those details, too.


According to that document, this is how ACHD determines that a mitigation plan is acceptable:

Step 1: ACHD reviews the mitigation plans to ensure facilities have accounted for all sources of PM2.5/PM10.

Step 3:  If the plan is deemed acceptable, ACHD will accept it conditionally. It is considered to be in effect upon being submitted. At this point, Air Quality Staff will perform an air quality modeling analysis to assess the impact of the plans on PM2.5 for the region. “Depending on the results, ACHD may notify the source that modifications to their plan are needed,” the document notes.

Step 2: ACHD will then review the feasibility of the proposed methods of reducing particulate pollution based on total decreases and the facility’s total permitted limits.

Step 4: If the plan is deemed insufficient, ACHD will provide a written explanation of why it was rejected and ask for the source to submit revisions.

What's the big deal about
particulate pollution?

Particulate matter is one of the most prevalent types of air pollution. It is one of six types of air pollution known as Criteria Pollutants and because they are known to cause harm to the environment and human health, the EPA has set science-based guidelines for how much of each one is permitted in the air. 


These limits are known as National Ambient Air Quality Standards (NAAQS), and they were designed to prohibit pollution concentrations that could adversely affect people’s health.  Just as a reminder, while these are national standards, these pollutants are monitored by the Allegheny County Health Department Air Quality Program.  


In addition to being one of the most prevalent forms of pollution, particulate matter is also one of the most dangerous. Have you seen recent headlines about the Mon Valley making the list of places with the worst air quality in the country? The area made those lists because of spiked levels of particulate matter.


Particulate matter pollution is referred to as PM. It is a complex mix of airborne particles and droplets of liquid made up of:


  • Acids like nitrates and sulfates

  • Ammonium

  • Water

  • Black carbon

  • Organic chemicals

  • Metals

  • And soil matter 


The EPA breaks down particle pollution into two main groups: Coarse particulates and fine particulates.

Coarse particulate pollution is more commonly referred to with an acronym – PM10. Why? Because it refers to all particle pollution that is less than 10 microns in size. How big is a micron? To give some perspective, a single strand of human hair is a thickness of about 50 microns. This type of particulate matter pollution, because of its larger size, can get stuck in nose hairs, cilia, and secretions in the throat. PM10 is irritating to the nose, throat, lungs, and eyes. 


Common types of coarse particle pollution include dust, pollen, smoke, and dirt.


Fine particulate matter is more commonly referred to as PM2.5. You can probably guess why: It refers to all particulate matter pollution that is less than 2.5 microns. Fine particulate matter pollution is more harmful to human health because it’s smaller and more able to infiltrate the body through the nose, mouth, and skin. This means they can travel deep into the lungs and even into the bloodstream.


PM2.5 is referred to as primary if it is directly emitted into the air and as secondary if it’s created as a result of chemical reactions from gases mixing in the atmosphere.


There are myriad sources of PM2.5, but the most common include:


  • Exhaust from cars and trucks

  • Exhaust from diesel engines (including construction and other machinery)

  • Open burning (i.e. wildfires, fireplaces, woodstoves)

  • Cooking

  • Dust from roads and construction on them

  • Agricultural operations

  • Combustion of coal and oil

  • Emissions from industrial processes such as oil refining, steel making, as well as the production of paper and the refinery of oil

Why do you need to be concerned about PM2.5 exposure?

So. Many. Studies. have provided damning evidence that exposure to particulate matter pollution has significant health consequences and the size of the particle matters – larger particles are linked to inflammation of the respiratory system, bronchitis, asthma, allergies, coughing, reduced lung capacity.  

But those tinier particles? Those are far more hazardous to human health: PM2.5 is linked to heart attacks, strokes, arrhythmias, and lung cancers. Exposure to PM2.5 is also linked to everything from baldness to dementia to mental illness


If you take away nothing else, remember this: There is no safe level of PM2.5 pollution.


According to the EPA, exposure to particulate matter hits children, the elderly, and those with pre-existing conditions harder than most. For these folks, PM2.5 has been shown to cause:


  • Increased hospital admissions

  • Increased emergency room visits

  • Absences from work and/or school

  • A restriction in participation in outdoor activities


It’s important to remember that these very real health impacts are the reason why the new episode rules were formulated – to protect our friends and neighbors in the Mon Valley who are continually confronted with these short-term periods of abysmal air quality.

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