Air Quality Monitoring Data
Bethel Particulate Matter 10 (PM10)
The interactive charts below show historical data from PM10 monitoring at the Bethel air quality monitoring site. Sampling began on June 6th, 2018 and ended in June 2020. The Alaska Air Monitoring Plan contains more information about this monitor.
Note: The vertical axis of these charts extends to 200 µg/m3. The PM10 concentrations are made at standard conditions and are corrected for local temperature and pressure.
The following graphs show the 24-hour averaged PM10 concentrations measured at the Bethel monitoring site from 2019 through 2018.
2019
2018
Glossary
Glossary
- NAAQS
- National Ambient Air Quality Standard - A health-based air quality standard set by EPA based on a review of available scientific information. NAAQS exist for criteria pollutants including Particulate Matter (PM2.5 and PM10), Carbon Monoxide (CO), Sulfur Dioxide (SO2), Nitrogen Dioxide (NO2), Ozone(O3), and Lead(Pb).
- EPA's NAAQS Webpage
- Concentration, µg/m3
- The amount of PM2.5 suspended in the air with units of micrograms(one-millionth of a gram) per cubic meter
- Exceedance
- A day when the 24-hour measured concentration of PM2.5 exceeds the NAAQS.
- 98th Percentile
- The daily value out of a year of PM2.5 monitoring data below which 98 percent of all daily values fall. 40 CFR 50 Appendix N - see section 4.5(a)
- 24-hour Design Value (DV)
- A three-year average of the 98th percentile value. An area is in violation of the NAAQS when the Design Values is greater than the 24-hour NAAQS for PM2.5, which is currently set at 35 µg/m340 CFR 50 Appendix N - see section 4.5(b)
- Clean Data Year
- A year when the 98th percentile value is less than the NAAQS.
- Exceptional Events
- Unusual or naturally occurring events that can affect air quality but are not reasonably controllable.
- EPA's Exceptional Events Webpage
- DEC's Exceptional Events Webpage
- Compliance with PM2.5 NAAQS
- 24-Hour: 98th percentile, averaged over 3 years, must be below the standardAnnual: Annual arithmetic mean, averaged over 3 years, must be below the standard. 40 CFR 50 Appendix N - see sections 4.1 and 4.2
PM2.5 NAAQS Values
| Standard | 1997 - 2006 | 2006 - 2012 | 2012 - 2024 | 2024 - current |
|---|---|---|---|---|
| 24-hour | 65 µg/m3 | 35 µg/m3 | 35 µg/m3 | 35 µg/m3 |
| Annual | 15 µg/m3 | 15 µg/m3 | 12 µg/m3 | 9 µg/m3 |