Understanding the New PM2.5 Standard

What's up, Forsyth?? In this blog post, we will explain an important regulatory change from the US Environmental Protection Agency (EPA) that affects the air quality monitoring and forecasting activities of our agency.

The Forsyth County Office of Environmental Assistance and Protection
provides daily air quality forecasts for fine particulate matter 365 days per year.

A New Standard!  

On February 7, 2024, EPA revised the primary annual health-based national ambient air quality standard (NAAQS) for fine particulate matter (PM2.5), changing the level from 12 micrograms per cubic meter of air (μg/m3) to 9 μg/m3. EPA periodically reviews and updates NAAQS based on the latest available scientific data and technical information. While the primary annual NAAQS for PM2.5 has become more protective, EPA has not revised any of the other PM NAAQS, including the primary 24-hour PM2.5 standard of 35 μg/m3, for 2024. 


Watch US EPA Administrator Michael Regan as he signs and comments on the new rule and what this will mean for current and future generations of Americans. This video can be found on YouTube at https://www.youtube.com/watch?v=YQH-6AMLRiU


Wait…what are standards?  

The Clean Air Act requires NAAQS for six ‘criteria’ air pollutants: carbon monoxide, lead, sulfur dioxide, nitrogen oxides, particulate matter, and ground-level ozone. All except carbon monoxide have both primary and secondary standards. According to EPA, primary standards “provide public health protection, including protecting the health of ‘sensitive’ populations such as asthmatics, children, and the elderly, whereas secondary standards provide public welfare protection, including protection against decreased visibility and damage to animals, crops, vegetation, and buildings.  

Why did they make this change? 

Large portions of the U.S. population, including children and older adults, people with heart or lung disease, communities of color, and those of lower socioeconomic status, are at a greater risk of experiencing adverse health effects related to exposure to fine particulate matter. EPA estimates that by 2032, we could save up to $46 billion in public health care costs as a result of the strengthened PM2.5 standard. Other anticipated benefits (by 2032) include up to 4,500 avoided premature deaths, 800,000 avoided cases of asthma symptoms, and 290,000 avoided lost workdays. EPA also explains that improved air quality will result in healthier workers and families, which will help grow our economy.  

What does this mean for Forsyth County air quality monitoring and Triad air quality forecasts? 

While the 24-hr PM2.5 standard will remain the same, the change in the annual PM2.5 standard does affect the breakpoints between some of the Air Quality Index (AQI) color codes for daily forecasts. Effective May 6, Code Yellow (moderate) will begin at 9.1 μg/m3 instead of 12.1 μg/m3. Changes to the breakpoints between Code Red and Code Purple, and between Code Purple and Code Maroon, were also made, though these should rarely, if ever, affect Triad Air Quality forecasts. The North Carolina Department of Environmental Quality’s Division of Air Quality has provided a table showing these changes (Figure 1), as well as a general overview of North Carolina’s status in regards to the new PM NAAQS 


Screenshot (taken April 4, 2024) from NCDEQ’s website showing the new changes in AQI breakpoints for PM2.5. 


As a result of these changes, we can expect to see many more Code Yellow air quality days for PM2.5 than we have experienced in recent years. This does not mean that our air quality is getting worse, but rather it reflects the most current scientific knowledge we have regarding the health effects of PM2.5 exposure. While it can feel unsettling or frustrating that our scientific understanding of a subject may evolve overtime, this NPR article explains why this is actually a good thing.  

Remember to stay informed! 

If you have not already signed up for air quality alerts and/or daily air quality forecasts, please sign up through enviroflash.info, or visit our Triad Air Quality Forecast page, which is updated at around 3:30pm each day. To stay up to date on current air quality events or topics in the Triad, follow us on Facebook, Instagram, or X 

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