2024 PM2.5 Annual Standard
A More Stringent Air Quality Standard
Effective May 2024, EPA tightened the annual health-based National Ambient Air Quality Standard for fine particulate matter (PM2.5) from 12.0 µg/m3 to 9.0 µg/m3.
This change was made after a review of the available scientific evidence, technical information, and advice of an independent scientific panel. EPA says lowering the standard will result in significant public health benefits, advance the economy and improve quality of life.
According to EPA, in 2032, the stronger standard will avoid 4,500 premature deaths, 800,000 cases of asthma symptoms, and 290,000 lost workdays, with $46 billion in public health savings. PM2.5 is a pollutant of great concern to people with asthma or lung disease and to already overburdened and vulnerable populations, including many communities of color and low-income communities.
The N.C. Division of Air Quality wants to make sure North Carolina residents know and understand what the new standard means for them. We are developing and sharing information about PM2.5 and will update this page with the latest resources. The fact sheet linked below provides an overview of what PM2.5 is and what PM2.5 pollution there is in North Carolina.
North Carolina Status
North Carolinians are breathing the cleanest air in decades. North Carolina has seen a 48% decline in PM2.5 emissions between 1990 and 2022, due to efforts of state leaders, regulatory agencies, electric utilities, industry and the public. (Read more in our latest Air Quality Trends report.) All areas of North Carolina are in attainment with the previous PM2.5 annual standard (12.0 µg/m3). North Carolina will continue working with stakeholders to ensure the state’s air quality will meet the new PM2.5 standard.
Compliance with the new standard is determined by calculating a "design value", which is based on the latest three years of certified monitoring data. The latest design values (2023-2025) show that all 20 monitors in North Carolina used for determining attainment with the new PM2.5 standard are meeting the new standard. On March 9, 2026, the EPA classified one monitoring site (Remount monitor in Mecklenburg County) as microscale; therefore, it is not eligible for comparison to the annual PM2.5 NAAQS.
Initial calculations for 2023-2025 design values showed the Davidson County monitoring site was slightly above the new standard, due to influences of Canadian wildfire smoke. Without the influence from Canadian wildfire smoke, none of North Carolina's monitors would have exceeded the new standard in 2023.
DAQ recommended that EPA designate all of North Carolina as in attainment with the revised PM2.5 standard, because the Canadian wildfires were exceptional events outside of the state’s control. This would allow DAQ to focus on pollution reduction strategies that are within its control to ensure ongoing attainment with the revised standard. To support that recommendation, the state prepared an Exceptional Events Demonstration that clearly shows that for the Davidson County monitor, Canadian wildfire smoke negatively impacted air quality data. Because this exceptional event was outside the control of the state, a small number of days in June and July 2023 can be removed from the calculation when determining compliance with the revised PM2.5 standard, upon EPA approval of the Exceptional Events Demonstration. Exceptional Events Demonstrations are authorized under the Clean Air Act and EPA governs how states can use these provisions. The EPA concurred with the DAQ's Exceptional Events Demonstration for the Davidson County monitor on September 3, 2026. After accounting for the approved Exceptional Events Demonstration, all monitors in North Carolina used for determining attainment with the new PM2.5 standard are showing three-year design values at or below the new standard of 9.0 µg/m3. The relevant supporting documents are linked below.
Documents
- North Carolina's Designation Recommendation Letter (Dec. 23, 2024)
- Exceptional Events Demonstration (Feb. 6, 2025)
- EPA Exceptional Events Concurrence Letter (Sept. 2, 2025)
- North Carolina's Request for EPA Review of Deferred Exceptional Events Data (Jul. 17, 2026)
- EPA Concurrence Letter for Deferred Exceptional Events (Sept. 3, 2026)
- EPA "120-Day Letter" for North Carolina (Sept. 29, 2026)
- North Carolina's response to EPA's "120-Day Letter" and Initial Designation (Oct. 30, 2026)
When a new air quality standard is announced, the designation process as defined by federal rule takes two years to complete. If the air quality in a geographic area meets or is cleaner than the national standard, it is called an attainment area (designated “attainment/unclassifiable”). Areas not meeting the standard are designated as “nonattainment.” The process involves state input and public comment opportunities.
Within one year of the revised standard, states must submit to EPA their recommended designations under the new value, based on the latest monitoring data available at the time. EPA has said it will consider impacts from wildfire smoke when making designations if the state submits an exceptional event demonstration for the dates impacted by wildfire smoke for all affected monitors. EPA’s Exceptional Events rule establishes criteria and procedures for use in determining if air quality monitoring data has been influenced by exceptional events such as wildfire smoke.
On December 23, 2024, the DAQ recommended attainment for all areas of North Carolina, followed by an Exceptional Events Demonstration submitted on February 6, 2025, which clearly shows that Canadian wildfire smoke negatively impacted air quality data for certain monitors in 2023. The EPA concurred with the Exceptional Events Demonstration on September 2, 2025 (for monitors with regulatory significance based on 2022-2024 design values), and September 3, 2026 (for monitors with regulatory significance based on 2023-2025 design values).
Due to pending litigation and the EPA’s pending (at the time) motion for vacatur of the 2024 PM2.5 NAAQS revision, the EPA did not issue final designations by the due date of February 7, 2026. On June 26, 2026, the U.S. Court of Appeals for the District of Columbia Circuit denied the petitions for review and EPA’s motion for vacatur, and on July 17, 2026, the U.S. District Court, Northern District of California ruled that EPA must promulgate the final PM2.5 designations for all areas of the country no later than February 6, 2027.
On September 29, 2026, the EPA issued initial designations for states, indicating a statewide designation of “attainment/unclassifiable” for all of North Carolina. EPA’s final designations are due by February 6, 2027. The DAQ is preparing its infrastructure state implementation plan (iSIP) pursuant to Section 110(a) of the Clean Air Act (CAA), which is also due by February 6, 2027. When available, further information about the 2024 annual PM2.5 NAAQS iSIP will be available on our Certifications for CAA Section 128 and 110(a) Infrastructure webpage.
Keeping PM2.5 levels low in 2024 will be critical for attaining the new standard.
Over the past few years, DAQ has conducted PM2.5 outreach with community groups after the EPA revised the annual PM2.5 standard. This included outreach in Mecklenburg and Davidson counties, which an initial data review identified as the two areas closest to the revised standard of 9.0 µg/m³. As noted above, the Mecklenburg County monitor (Remount) has since been reclassified as a microscale site and is not comparable to the annual PM2.5 NAAQS.
As part of those outreach efforts, DAQ hosted an informational webinar covering what PM2.5 is, where it comes from, and our plan for submitting an attainment designation recommendation to the EPA supported by an exceptional events demonstration (which DAQ has since completed). The webinar also explains how we keep the public informed and safe during periods of elevated air pollution, such as particulate matter or ozone, including days affected by wildfire smoke. You can download the slides or watch the webinar recording below. Please note that because these materials were published in late 2024, they contain some outdated references alongside relevant background information.
You can view the full webinar translated into Spanish on YouTube.
Air Quality Index
The revised PM2.5 annual standard also adjusts Air Quality Index (AQI) levels. As of May 6, 2024, there are more stringent targets for Code Green “good" days. You may observe more Code Yellow “moderate" days annually than in previous years due to this change in the AQI. The below table has information on the new breakpoints for Code Green, Code Yellow and other AQI color codes.
Air quality forecasts are available every day for all 100 North Carolina counties online from the Air Quality Portal.
| AQI Category and Index Value | Previous AQI Category Breakpoints | Updated AQI Category Breakpoints | What changed? |
|---|---|---|---|
| Good (0 – 50) | 0.0 to 12.0 | 0.0 to 9.0 | EPA updated the breakpoint between Good and Moderate to reflect the updated annual standard of 9 micrograms per cubic meter |
| Moderate (51 – 100) | 12.1 to 35.4 | 9.1 to 35.4 | |
| Unhealthy for Sensitive Groups (101 – 150) | 35.5 to 55.4 | 35.5 to 55.4 | No change, because EPA retained the 24-hour fine PM standard of 35 micrograms per cubic meter. |
| Unhealthy (151 – 200) | 55.5 to 150.4 | 55.5 to 125.4 | EPA updated the breakpoints at the upper end of the unhealthy, very unhealthy, and hazardous categories based on scientific evidence about particle pollution and health. The Agency also collapsed two sets of breakpoints for the Hazardous category into one. |
| Very Unhealthy (201 – 300) | 150.5 to 250.4 | 125.5 to 225.4 | |
| Hazardous (301+) | 250.5 to 350.4 and 350.5 to 500 | 225.5+ |
Take Action to reduce harmful PM2.5
There are many ways North Carolinians can help reduce PM2.5:
- Never burn trash or other man-made materials.
- Burn dry, seasoned wood to reduce smoke from fire pits or woodstoves.
- Reduce driving: Telework, carpool, ride your bike, or ride public transit, and bring your lunch to work rather than driving to lunch.
- Keep vehicles in good working condition.
- Use electric or hand-powered lawn equipment or reduce use of gasoline-powered lawn equipment.
- Attend community-wide firework displays instead of having your own fireworks.
- When making an outdoor grill purchase, opt for propane, gas, or electric rather than charcoal or wood.
Ongoing efforts
DEQ continues to work with stakeholders and our partners to achieve reductions in PM2.5 emissions. Efforts include:
- Supporting the adoption of clean and all-electric cars and trucks through our Mobile Sources Emissions Reductions grant and Volkswagen Settlement grant programs.
- Ensuring compliance of regulated sources of air pollution.
- Responding to reports of dust, smoke and vehicle emissions that violate air quality rules.
- Educating the public on the impacts and sources of air pollution.
- Provide education opportunities and online information to learn about the designation process and the exceptional events rule and how DAQ takes steps to help protect peoples health and share air quality information throughout the year.