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Division of Air Quality Monitoring and Quality Assurance

Air Quality Monitoring Data

Realtime Air Quality Data

Butte Particulate Matter 2.5 (PM2.5)

The interactive charts below show historical data from this monitor. The Alaska Air Monitoring Plan contains more information about this monitor.

Note: The vertical axis of these charts extends from -10 µg/m3 to 100 µg/m3. Negative PM2.5 concentrations are included based on EPA reporting guidelines and are within the noise levels of the instrument when the ambient PM2.5 concentration is near zero. The PM2.5 concentrations represent the concentration at local conditions and have not been corrected for local temperature and pressure.

The following graphs show the 24-hour averaged PM2.5 concentrations measured at the Butte Air Quality Monitor from 2023 through 2000.

2020

The 2020 PM2.5 24-hour concentrations were below the 24-hour NAAQS of 35 µg/m3. No data were flagged as exceptional events this year. The 98th percentile concentration was 24 µg/m3.

2019

The 2019 PM2.5 24-hour concentrations were below the 24-hour NAAQS of 35 µg/m3. No data were flagged as exceptional events this year. The 98th percentile concentration was 27.7 µg/m3.

2018

The 2018 PM2.5 24-hour concentrations were below the 24-hour NAAQS of 35 µg/m3 with the exception of one day. No data were flagged as exceptional events this year. The 98th percentile concentration was19.2 µg/m3.

2017

The 2017 PM2.5 24-hour concentrations were below the 24-hour NAAQS of 35 µg/m3 with the exception of four days. No data were flagged as exceptional events this year. The 98th percentile concentration was 26.2 µg/m3.

2016

The 2016 PM2.5 24-hour concentrations were below the 24-hour NAAQS of 35 µg/m3 with the exception of two days. No data were flagged as exceptional events this year. The 98th percentile concentration was 29.2 µg/m3.

2015

The 2015 PM2.5 24-hour concentrations were below the 24-hour NAAQS of 35 µg/m3 with the exception of eleven days. No data were flagged as exceptional events this year. The 98th percentile concentration was 37.9 µg/m3

2014

The 2014 PM2.5 24-hour concentrations were below the 24-hour NAAQS of 35 µg/m3 with the exception of nine days. The exceedance measured in May was caused by wildfire smoke. No data were flagged as Exceptional Events this year. The 98th percentile concentration was 39.5 µg/m3.

*Photo: See Photo taken December 18, 2014 (PDF) (PDF 750K)

2013

The 2013 PM2.5 24-hour concentrations were below the 24-hour NAAQS of 35 µg/m3 with the exception of two days in January and two days in November. No data were flagged as Exceptional Events this year.  The 98th percentile concentration was 27.9 µg/m3.

2012

The 2012 PM2.5 24-hour concentrations were below the 24-hour NAAQS of 35 µg/m3 with the exception of four days in December. No data were flagged as Exceptional Events this year. The 98th percentile concentration was 33.4 µg/m3.

2011

NOTE: In August 2011, the primary PM­2.5­ sampler changed from a filter based sampler operating on a 1-in-6 day schedule to a continuous monitor, leading to an increase in the quantity of data.

The 2011 PM2.5 24-hour concentrations were below the 24-hour NAAQS of 35 µg/m3. No data were flagged as Exceptional Events this year. The 98th percentile concentration was 30.2 µg/m3.

2010

The 2010 PM2.5 24-hour concentrations were below the 24-hour NAAQS of 35 µg/m3 with the exception of two days in January and one day in March. No data were flagged as Exceptional Events this year. The 98th percentile concentration was 37.5 µg/m3.

2009

The 2009 PM2.5 24-hour concentrations were below the 24-hour NAAQS of 35 µg/m3 with one exception in July. No data were flagged as Exceptional Events this year. The 98th percentile concentration was 28.8 µg/m3.

2008

The 2008 PM2.5 24-hour concentrations were below the 24-hour NAAQS of 35 µg/m3. No data were flagged as Exceptional Events this year. The 98th percentile concentration was 30.8 µg/m3.

2007

The 2007 PM2.5 24-hour concentrations were below the 2006 24-hour NAAQS of 35 µg/m3. No data were flagged as Exceptional Events this year. The 98th percentile concentration was 20.1 µg/m3.

2006

NOTE: In 2006 EPA strengthened the National Ambient Air Quality Standard by lowering the concentration to 35 µg/m3.

The 2006 PM2.5 24-hour concentrations measured were below the new 24-hour NAAQS of 35 µg/m3 with the exception of two days in January, one day in June, and one day in November. No data were flagged as Exceptional Events this year. The 98th percentile concentration was 40 µg/m3.

2005

The 2005 PM2.5 24-hour concentrations were below the 1997 24-hour NAAQS of 65 µg/m3. No data were flagged as Exceptional Events this year. The 98th percentile concentration was 25.2 µg/m3.

2004

The 2004 PM2.5 24-hour concentrations were below the 1997 24-hour NAAQS of 65 µg/m3. No data were flagged as Exceptional Events this year. The 98th percentile concentration was 27.5 µg/m3.

2003

The 2003 PM2.5 24-hour concentrations were below the 1997 24-hour NAAQS of 65 µg/m3. No data were flagged as Exceptional Events this year. The 98th percentile concentration was 30.3 µg/m3.

2002

The 2002 PM2.5 24-hour concentrations were below the 1997 24-hour NAAQS of 65 µg/m3. No data were flagged as Exceptional Events this year. The 98th percentile concentration was 34.6 µg/m3.

2001

The 2001 PM2.5 24-hour concentrations were below the 1997 24-hour NAAQS of 65 µg/m3. No data were flagged as Exceptional Events this year. The 98th percentile concentration was 29.3 µg/m3.

2000

The 2000 PM2.5 24-hour concentrations were below the 1997 24-hour NAAQS of 65 µg/m3. No data were flagged as Exceptional Events this year. The 98th percentile concentration was 27.8 µg/m3.

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

Last Updated: 4/17/2024
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Department of Environmental Conservation

Mailing Address:  P.O. Box 111800
Juneau, Alaska 99811
Location:  410 Willoughby Avenue, Juneau