Monitored Data

Air Quality operates an extensive network of air monitoring equipment throughout the county.

This network collects information on a variety of pollutants, including criteria pollutants and hazardous air pollutants (HAPs).

Hourly Data

View the Key to Air Quality Data(PDF, 107KB).

This hourly data is unverified. It is automatically generated by our network of air monitoring stations and is not considered official until it is reviewed by qualified members of our staff. Sometimes, an electrical disruption or equipment malfunction can result in erroneous data.

Note: On April 15, 2022, the Allegheny County Health Department learned that for the second year in a row, the county has met federal air quality standards for fine particulate matter (PM2.5) at all eight air quality monitors. This table shows the highest air quality concentrations recorded(PDF, 67KB) at any site over the most recent three years (based on maximum three-year averages), given by pollutant and averaging duration.

We carefully monitor our equipment; however, unusual or worrisome data can be reported by calling 412-687-ACHD (2243).

Air Dispersion Reports

Each day, we issue an air dispersion report called the Air Quality Forecast and Dispersion outlook report (see our main Air Quality page). This report is designed to forecast how weather conditions will influence the concentration of contaminants in the air.

To learn more about air dispersion or for help understanding the daily report, read our Air Dispersion Conditions & Outlook Guide(PDF, 171KB).

Air Quality Annual Reports

Each year, all of our verified data is collected and analyzed as part of our Air Quality Annual Report. You can view all of our Annual Reports on our Air Quality Reports and Studies page.

About the Pollutants We Track

Criteria Pollutants

The Environmental Protection Agency (EPA) has identified six common air pollutants that are important to measure and track. These are known as "Criteria Pollutants". They are:

  • Particle pollution
  • Ozone
  • Carbon monoxide
  • Sulfur dioxide
  • Nitrogen oxides
  • Lead

Because these pollutants can harm human health and the environment, the EPA has set science-based guidelines for how much of each pollutant should be in the air. These limits, known as National Ambient Air Quality Standards (NAAQS), are designed to help avoid pollution concentrations that could adversely affect our health.

Hazardous Air Pollutants

Also known as air toxics, hazardous air pollutants (HAPs) are pollutants that are known or suspected to cause cancer or other serious health effects. Examples of toxic air pollutants include:

  • Benzene
  • Perchlorethlyene
  • Methylene chloride
  • Dioxin
  • Asbestos
  • Toluene
  • Cadmium
  • Mercury
  • Chromium
  • Lead compounds

The EPA has designated 187 hazardous air pollutants. To see the full list, visit the EPA website.

Most HAPs originate from human-made sources, including mobile sources (e.g., cars, trucks, buses) and stationary sources (e.g., factories, refineries, power plants), as well as indoor sources (e.g., some building materials and cleaning solvents). Some HAPs are released from natural sources such as volcanic eruptions and forest fires.

National Emission Standards for Hazardous Air Pollutants (NESHAPs) are EPA set emission limits for air toxics. The standards for a particular type of source (such as dry cleaners or gasoline stations) are known as the Maximum Achievable Control Technology (MACT). Standards for air toxics are authorized under the Clean Air Act, section 112.

ACHD Article XXI §2104.08(PDF, 2MB) PA rules on air toxics including any additions or changes made by the EPA.

In addition, ACHD's Air Quality program has protocols in place to help regulate and control these toxic air pollutants, as well as respond to new data concerning air toxic “hotspots” and areas of interest.

Our Air Toxic Guidelines, which are followed by ACHD permit engineers when issuing air permits for new and existing sources of air toxics in Allegheny County, were originally developed in 1988 and have recently been revised by ACHD.