top of page

UPDATED: Residents’ Guide to Allegheny Co. Health Dept's '24 Network Monitoring Plan, How to Comment

Updated: Jan 17

The comment period is now over. Thanks to all who submitted a comment. You can read GASP's formal comments here.

If you follow local air quality issues, then you probably know that the Allegheny County Health Department (ACHD) is our local air quality regulator and operates a network of air quality monitors.

What you might not know is that every year, the ACHD must publish an air quality network monitoring plan that provides a detailed description of how and where air pollution is monitored throughout the county.

These annual reports are required by the U.S. Environmental Protection Agency (EPA) and provide information such as the specific location of each monitoring station, monitoring methods, monitoring objectives, frequency of sampling, pollutants measured, and any planned changes to the network.

Right now, ACHD is seeking public comment on its 2024 Air Quality Network Monitoring Plan through Dec. 1, so GASP wanted to provide a breakdown of what’s new and notable in the report and how - and why - you should consider speaking out.

Where, What, When, and Why Does ACHD Monitor?

ACHD operates nine monitoring sites to meet the core objectives for all monitoring networks across the country:

  1. Provide air pollution data to the general public in a timely manner;

  2. Support compliance with ambient air quality standards and emissions strategy development; and

  3. Support for air pollution research studies.

The complexity of the sites and the pollutants they measure vary by the sites’ objectives, with a site in Glassport monitoring a single pollutant – PM10 – and ACHD’s primary site in the City of Pittsburgh monitoring dozens of pollutants.

The monitoring site locations are established to meet certain objectives. For example, there is a near-road site along the Parkway East set up expressly to monitor pollutants from mobile sources and other sites that have changed over time to detect the highest levels or background levels of certain pollutants.

Many sites now monitor continuously as technology and internet connectivity have advanced, but not all pollutants can be monitored in real-time.


In the 76-page plan, ACHD detailed monitoring additions since the publication of its 2023 Air Quality Network Monitoring Plan. They include:

• Moving the Avalon monitoring station to the Avalon Elementary School

• Reconfiguring the Liberty site roof and replacing the continuous PM2.5 and PM10 monitors at that site

• Adding aerosol chemical speciation monitoring for organics, sulfate, nitrate, ammonium, and chloride to the Lawrenceville site

• Adding continuous PM10 metals monitor to the Lawrenceville site

The Plan also lays out updates ACHD anticipates it will complete in the next 18 months, which include:

• Addition of continuous PM2.5 monitoring at the South Fayette and Harrison sites

• Addition of meteorology (wind speed & direction) sensors at the Avalon site

• Addition of meteorology sensing as well as hydrogen sulfide (H2S) and sulfur dioxide (SO2) monitoring at the Clairton site

• Addition of True NO2 monitoring at the Liberty site

• Addition of a ceilometer to the Mon Valley to measure the mixing layer height of the atmosphere

• Movement of Lawrenceville monitoring station – the department’s primary and most comprehesive monitoring site – to the Chateau Neighborhood in Pittsburgh’s North Side.

As GASP reported previously, closing the Lawrenceville site did not strike us as a well-reasoned decision, but the relocation is moving ahead. One bright spot is that ACHD is proposing to operate a new monitoring station within two miles of the existing Lawrenceville station “to capture a similar airshed to what is being monitored now at the NCore site for long-term comparison to the new Chateau NCore site.”

Cheers and Jeers for This Year’s Plan

Technically speaking, and regarding the pollutants that ACHD will be monitoring, GASP has nothing but cheers for the plan. The network is expanding, new monitors are being deployed, and more pollutants are being measured.

In addition, ACHD is currently field-testing low-cost sensors for potential use as supplemental monitoring in environmental justice communities throughout the county. After field testing of Purple Air PA-II-FLEX sensors, ACHD will provide the monitored area with correction factors to properly calibrate citizen-owned sensors to the closest continuous regulatory PM2.5 monitor. This is a great idea.

But a jeer is necessary when it comes to ACHD meeting objective #1 for monitoring networks: Providing air pollution data to the general public. To be clear, ACHD publishes air quality data hourly, and the Air Quality Program website displays PM2.5 data based on rolling averages, but the department’s refusal to promote and share the EPA’s NowCast AQI – particularly during the wildfire smoke episodes this past summer – deeply concerns us.

The core issue with ACHD’s approach is that a rolling average is not the same thing as a current condition. In other words, “we’ve averaged 0.14 inches of rain over the past 24 hours” is not a reasonable or sane answer to the simple question, “Is it raining outside now?”

It is reasonable and sane for the public to want actual, current air quality conditions, and the EPA’s AirNow platform delivers. It displays hourly data from thousands of monitors across the country and – more importantly – AirNow calculates its NowCast AQI values to be responsive to rapidly changing air quality conditions and to caution people in time for them to reduce their exposure to pollutants.

With that in mind, consider those days last summer when air quality locally was in the very unhealthy range. ACHD outreach encouraged the public to, “[s]tay up to date on current air quality conditions by visiting the department’s online dashboard,” which – as we noted above – does not report current conditions.

“There appears to be a troubling disconnect between the quality of the data ACHD captures and the department’s curious approach to sharing and interpreting that data for the public’s benefit,” GASP staff attorney Ned Mulcahy said. “EPA regulations define the AQI as ‘a tool that simplifies reporting air quality to the general public.’ ACHD is both complicating the air quality reporting and failing to promote a tool meant to protect public health.”

How and Why to Submit a Public Comment

GASP will be submitting formal comments on the plan this Friday. If you’d like to echo our sentiments above or raise other concerns about how air quality is monitored in Allegheny County, submitting a formal public comment is simple.

You can email them to ACHD’s David D. Good at or mail them to: 301 39th Street, Building 7, Pittsburgh, PA 15201.

For more information, there is also an online meeting, Wednesday, Nov. 29, of the Air Quality Program Advisory Committee’s Air Monitoring Subcommittee where a discussion of the monitoring plan is on the agenda.

bottom of page