2024 PM2.5 Annual Standard
In February 2024, EPA announced it will tighten 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 is being 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.
EPA decided to not change the following standards at this time:
- The secondary (welfare-based) annual PM2.5 standard (15.0 µg/m3)
- The primary and secondary 24-hour PM2.5 standard (35 µg/m3)
- The primary and secondary 24-hour PM10 standard (150 µg/m3)
North Carolina Status
North Carolinians are breathing the cleanest air in decades. North Carolina has seen a 49% decline in PM2.5 emissions between 1990 and 2020, 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.
Based on certified monitoring data from 2021-2023, 19 out of 21 monitoring sites in North Carolina are meeting the new standard. However, the 2023 data shows two monitoring sites in the state were slightly above the new standard, due to influences of Canadian wildfire smoke. These sites, as seen in the map below, are in Mecklenburg and Davidson counties. Without the influence from Canadian wildfire smoke, none of North Carolina's monitors would have exceeded the new standard in 2023.
Two additional monitors, in Wake and Forsyth counties, were also tentatively above the new standard, based on uncertified 2023 data. However, during the certification of the data at these sites, EPA implemented an adjustment to correct for known biases in the data involving the type of particulate matter monitors used at these two sites. Now that the 2023 data has been certified, both of these monitors are showing compliance with the new standard.
Designation Process
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 will involve state input and public comment opportunities.
By February 7, 2025, the state has to submit to EPA designation recommendations based on certified monitoring data (2021-2023) and other factors, as applicable. EPA will review these recommendations, look at the current monitoring data available at that time (2022-2024), and then make the final designations by February 6, 2026.
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. DEQ is reviewing its monitoring data from 2023 in preparation for submitting an Exceptional Events demonstration to EPA for the two monitoring sites above 9.0 µg/m3.
Per EPA, attainment/nonattainment designations will likely be based on PM2.5 monitoring data collected from 2022-2024. Until all 2024 data is collected and reviewed, it is too early to know which, if any, areas of North Carolina may be in nonattainment with the new standard. Keeping PM2.5 levels low in 2024 will be critical for attaining the new standard.
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.