2001-2012 Evaluation of Colorado PM2.5 Data 

The PM2.5 NAAQS was promulgated in 1997. Because this was a new NAAQS, requiring new 

monitoring technology, the monitoring network was not deployed until January 1999. OAQPS is 

currently preparing a national summary of PM2.5 design values from 2001-2003 through 2010-2012 

based on certified data through 2012; that is planned for public release the week of August 26, 2013. I 

have extracted the Colorado portion of the monitor by monitor data from that material and attached it as 

an “Table 6”, below. I have color coded the data, using green to indicate valid 3-year design value (either 

annual mean or 24-hour mean of 98th percentiles) less than or equal to the NAAQS, blue for design value 

less than or equal to the NAAQS but not valid per 40 CFR Part 50 Appendix N (generally due to 

incomplete data) and yellow for a design value greater than the NAAQS, but again not a valid violation

per Appendix N, again usually due to incomplete data. 

The table from the OAQPS data set I used (Table 6) is the raw data underlying summary tables of 

regulatory data. The table is not intended to represent regulatory design values. Rather, it shows purely 

mathematical 3 year means of data. Other tables restrict reported data to only that which shows design 

values meeting regulatory data completeness requirements. I chose to use this more extensive nonregulatory dataset as a more comprehensive review of all available PM2.5 data from Colorado from 2001 

through 2012. Since it includes some data which is of no regulatory significance, I will discuss in detail 

in the text below any values above the current level of the standard indicated in the table. 

There are 3 monitors with Yellow design values (that is, means above the current level of the standard, 

but for which the calculated means are not valid per CFR). I have attached a pdf file with the data extract 

from AQS to allow me to explain why these incomplete design values over the NAAQs are no real 

concern. First, note that the Yellows occurred prior to 2005; at that time the levels of the standards were 

15 ug/m3 for the annual standard and 65 ug/m3 for the 24 hour standard, so the yellow values were not 

above the levels of the standard in place at the time they occurred. 

So, first, for monitor 08-001-0001, Commerce City, 2001-2003 annual mean shown equals 12.6 ug/m3, 

24 hr DV equals 57 ug/m3. This monitor operated from Jan. 26, 1999 to April 12, 2001 as a 1 day in 3 

sampler. Data from 1

st Quarter 1999 was incomplete (36% of scheduled samples were collected, 75% 

required for completeness) as were 2nd, 3rd and 4th quarter 2001 (no samples collected in those quarters, 

for 0% completeness). Appendix N would not allow a regulatory annual mean calculation with data this 

incomplete, particularly for 2001-2003 when data only were collected in the 1st 4 months of 2001, but 

OAQPS calculated a mathematical (not regulatory) mean for this period. The value is only above 12 

because the data from 2011 is dominated by high winter values without compensating lower spring and 

summer values not collected due to monitor shut-down. Means in 1999 and 2000, with more complete 

year-round data, are well below 12 ug/m3. For 24-hour PM2.5, only 3 exceedances were recorded in 26.5 

months of operation. The 98th percentiles in the nearly complete 1999 and 2000 were 24.9 and 23.3 

ug/m3, respectively, well below the 65 ug/m3 NAAQS at the time and the current 35 ug/m3 NAAQS. In 

2001, however, with the monitor only running until mid-April, and with exceedances on Feb. 16 and 17, 

the 98th percentile is the 1st max, 57.3 ug/m3 on Feb. 17. OAQPS uses this 98th percentile from 2001 as 

the non-regulatory DV for the 2001-2003 period (not a valid approach per Appendix N) to come up with 

an invalid design value for 2001-2003 of 57 ug/m3 that really has no validity for NAAQS comparison. 

Similarly for the National Jewish Hospital monitor, 08-031-0013, the monitor ran winters only, Nov. 20, 

1999 to March 30, 2000 and Nov. 1, 2000 to March 28, 2001 as part of a special study, not intended to be 

NAAQS compared. The Annual Mean 2001-2003 shown by OAQPS of 13.5 ug/m3 is based solely on 

the Jan.-March 2001 data, and is not valid per Appendix N, with no data from 2002 or 2003, and only 1 

quarter of data from 2001. Ditto for the 24-hour DV of 46 ug/m3. That is the second maximum of 4 

exceedances measured that February, but is not a valid design value for a 3 year period (with no date from 
2 of the 3 years). A valid design value is available for Denver from the CAMP monitor, 08-031-0002 for 

2001-2003, at 29 ug/m3. It had higher PM2.5 on each of the 4 days the National Jewish Monitor 

exceeded in Feb. 2001, and has complete data for the 3 year period, so is a much better indicator of the 

actual Denver PM2.5 air quality over the 2001-2003 time period than is the very incomplete data from the 

National Jewish Hospital monitor. 

For 08-031-0023, with yellow annual means over 12 ug/m3 in 2002-2004 and 2003-2005, a special study 

monitor operated at Swansea Elementary School as part of an air toxics study, the monitor only ran the

last 3 days of 2004 and then during all of 2005. So that 2002-2004 annual mean of 14.6 ug/m3 is in fact 

the average of Dec. 29, 30 and 31, 2004; this would not be a valid annual mean or design value in any 

context, and certainly not by Appendix N criteria. Likewise, the 2004-2006 mean lacks any 2006 data, 

and is also invalid for NAAQS comparison under CFR. The 2005 mean is only 10.14 ug/m3, so that is 

much more indicative of what a complete year of data in Denver actually looked like mid-2000s. 

Finally, Grand Junction, 08-077-0017 had a legitimate, valid 24-hour design value 2008-2010 of 35 

ug/m3. High winter PM2.5 in January 2009 and December 2009-January 2010 lead to 98th percentiles for 

2008-2010 of 25.2, 41 and 37.3 ug/m3 respectively; the design value of 34.5 ug/m3 rounds up to 35 

ug/m3 per 40 CFR Part 50, Appendix N. Since 2010, Grand Junction has not had a PM2.5 exceedance 

until January 2013, so the winters of 2009 and 2010 were somewhat unusual over the long term, and 

Grand Junction has maintained a design value equal to or below the NAAQS continuously from 2001 

through 2012. 

Elsewhere in the state, no monitor with complete data has come close to a NAAQS violation. Any other 

near misses have been statistical anomalies do to monitor malfunctions or shut-downs, rather than actual 

poor air quality. 
Colorado Data Extract, Edited by Richard Payton, EPA Region 8, 8/22/2013 

AQS Data Query: 07/10/2013; Last updated: 08/20/2013

Attains the 24-hour or Annual PM2.5 NAAQS with a valid 3-year Design value per 40 CFR Part 50 Appendix N

Design Value equal to or below the level of the NAAQS, but the design value is not valid (generally incomplete) per 40 C

Design Value above the level of the NAAQS, but the design value is not valid (generally incomplete) per 40 CFR Part 50 

Table 6. PM2.5 Site Design Value History, 2001-2003 through 2010-2012

Colorado Adams Denver-Aurora-Lakewood, CO Denver-Aurora, CO 8 08 001 080010001 12.6 NVColorado Adams Denver-Aurora-Lakewood, CO Denver-Aurora, CO 8 08 001 080010006 10.4 10.2 10.1 9.9 10.2 10.0 9.4 Colorado Arapahoe Denver-Aurora-Lakewood, CO Denver-Aurora, CO 8 08 005 080050005 8.9 8.3 8.1 7.8 8.0 7.6 7.2 Colorado Archuleta 8 08 007 080070001 6.0 NV 6.0 5.5 NV 5.1 NV 4.8 NV 4.6 NVColorado Archuleta 8 08 007 080070002 6.8 NVColorado Boulder Boulder, CO Denver-Aurora, CO 8 08 013 080130003 9.4 8.9 8.5 8.2 8.3 8.2 8.0 Colorado Boulder Boulder, CO Denver-Aurora, CO 8 08 013 080130012 8.0 7.5 7.1 6.8 7.0 6.9 6.8 Colorado Delta 8 08 029 080290004 8.0 8.2 7.6 7.3 7.0 NV 7.1 NVColorado Denver Denver-Aurora-Lakewood, CO Denver-Aurora, CO 8 08 031 080310002 10.8 10.0 9.7 9.1 9.3 8.8 8.5 Colorado Denver Denver-Aurora-Lakewood, CO Denver-Aurora, CO 8 08 031 080310013 13.5 NVColorado Denver Denver-Aurora-Lakewood, CO Denver-Aurora, CO 8 08 031 080310023 14.6 NV 12.4 NV 11.2 NV 9.8 9.1 8.7 Colorado Denver Denver-Aurora-Lakewood, CO Denver-Aurora, CO 8 08 031 080310025 9.9 NV 9.0 NV 8.4 NColorado Denver Denver-Aurora-Lakewood, CO Denver-Aurora, CO 8 08 031 080310026 Colorado Douglas Denver-Aurora-Lakewood, CO Denver-Aurora, CO 8 08 035 080350003 6.4 NVColorado Douglas Denver-Aurora-Lakewood, CO Denver-Aurora, CO 8 08 035 080350004 5.6 NV 5.9 NV 6.2 NV 6.3 6.1 Colorado Elbert Denver-Aurora-Lakewood, CO Denver-Aurora, CO 8 08 039 080390001 4.4 4.3 4.4 4.3 4.5 4.4 4.4 Colorado El Paso Colorado Springs, CO 8 08 041 080410008 6.9 6.7 6.7 6.7 6.7 NV 6.7 NVColorado El Paso Colorado Springs, CO 8 08 041 080410011 7.8 8.1 8.0 8.1 7.7 7.7 NV 7.5 NColorado El Paso Colorado Springs, CO 8 08 041 080410017 6.1 NV 5.8 NColorado Gunnison 8 08 051 080510005 6.9 6.7 6.4 NV 5.8 NV 6.1 NVColorado Gunnison 8 08 051 080510007 5.6 NV 6.0 NV 6.0 NV 6.4 NVColorado La Plata Durango, CO 8 08 067 080670008 5.7 6.1 NV 6.3 NVColorado La Plata Durango, CO 8 08 067 080677001 4.3 NColorado La Plata Durango, CO 8 08 067 080677003 3.8 NColorado Larimer Fort Collins, CO 8 08 069 080690009 7.9 7.6 7.3 7.3 7.4 7.3 7.1 Colorado Mesa Grand Junction, CO 8 08 077 080770003 7.8 7.8 NV 7.5 NVColorado Mesa Grand Junction, CO 8 08 077 080770017 10.4 NV 10.4 NV 9.2 9.5 9.2 9.4 9.4 Colorado Montezuma 8 08 083 080830006 6.0 NV 6.4 N

Colorado Pueblo Pueblo, CO 8 08 101 081010012 8.0 7.4 7.2 7.5 7.7 7.7 7.3 N

Colorado Pueblo Pueblo, CO 8 08 101 081010015 5.0 NColorado Rio Blanco 8 08 103 081030006 Colorado Routt 8 08 107 081070003 7.5 7.3 6.8 NV 6.7 NV 6.0 NVColorado San Miguel 8 08 113 081130004 5.6 5.1 4.8 4.5 4.5 NV 4.1 NVColorado Weld Greeley, CO Denver-Aurora, CO 8 08 123 081230006 9.0 8.5 8.1 8.1 8.4 8.4 8.2 Colorado Weld Greeley, CO Denver-Aurora, CO 8 08 123 081230008 9.6 8.8 8.5 8.6 9.3 9.3 8.7 

State County CBSA CSA EPA Region ST COU Site Annual Standard Design Values 1, 2 2001-2003 2002-2004 2003-2005 2004-2006 2005-2007 2006-2008 2007-2
Colorado Adams Denver-Aurora-Broomfield, CO Denver-Aurora-Boulder, CO 8 08 001 080010001 57 NV

Colorado Adams Denver-Aurora-Lakewood, CO Denver-Aurora, CO 8 08 001 080010006 27 24 23 24 29 30 29 Colorado Arapahoe Denver-Aurora-Lakewood, CO Denver-Aurora, CO 8 08 005 080050005 24 23 22 21 21 19 18 Colorado Archuleta 8 08 007 080070001 15 NV 16 12 NV 10 NV 8 NV 7 NVColorado Archuleta 8 08 007 080070002 14 NVColorado Boulder Boulder, CO Denver-Aurora, CO 8 08 013 080130003 26 24 22 19 22 24 23 Colorado Boulder Boulder, CO Denver-Aurora, CO 8 08 013 080130012 21 21 19 18 20 19 19 Colorado Delta 8 08 029 080290004 20 23 22 19 15 NV 16 NVColorado Denver Denver-Aurora-Lakewood, CO Denver-Aurora, CO 8 08 031 080310002 29 25 26 26 28 25 23 Colorado Denver Denver-Aurora-Broomfield, CO Denver-Aurora-Boulder, CO 8 08 031 080310013 46 NVColorado Denver Denver-Aurora-Lakewood, CO Denver-Aurora, CO 8 08 031 080310023 23 NV 25 NV 24 NV 26 25 24 Colorado Denver Denver-Aurora-Lakewood, CO Denver-Aurora, CO 8 08 031 080310025 20 NV 20 NV 20 NColorado Denver Denver-Aurora-Lakewood, CO Denver-Aurora, CO 8 08 031 080310026 Colorado Douglas Denver-Aurora-Broomfield, CO Denver-Aurora-Boulder, CO 8 08 035 080350003 15 NVColorado Douglas Denver-Aurora-Lakewood, CO Denver-Aurora, CO 8 08 035 080350004 17 NV 17 NV 18 NV 16 17 Colorado Elbert Denver-Aurora-Lakewood, CO Denver-Aurora, CO 8 08 039 080390001 12 11 11 14 15 14 11 Colorado El Paso Colorado Springs, CO 8 08 041 080410008 18 16 17 16 16 NV 14 NVColorado El Paso Colorado Springs, CO 8 08 041 080410011 18 18 17 16 16 20 NV 23 NColorado El Paso Colorado Springs, CO 8 08 041 080410017 14 NV 13 NColorado Gunnison 8 08 051 080510005 20 20 18 NV 14 NV 14 NVColorado Gunnison 8 08 051 080510007 15 NV 15 NV 15 NV 15 NVColorado La Plata Durango, CO 8 08 067 080670008 15 17 NV 14 NVColorado La Plata Durango, CO 8 08 067 080677001 9 NColorado La Plata Durango, CO 8 08 067 080677003 12 NColorado Larimer Fort Collins, CO 8 08 069 080690009 20 18 17 19 19 19 18 Colorado Mesa Grand Junction, CO 8 08 077 080770003 18 17 NV 16 NVColorado Mesa Grand Junction, CO 8 08 077 080770017 18 NV 23 NV 23 25 23 25 31 Colorado Montezuma 8 08 083 080830006 25 NV 20 N

Colorado Pueblo Pueblo, CO 8 08 101 081010012 18 17 15 16 15 16 16 N

Colorado Pueblo Pueblo, CO Pueblo-Cañon City, CO 8 08 101 081010015 10 NColorado Rio Blanco 8 08 103 081030006 Colorado Routt 8 08 107 081070003 17 17 15 NV 15 NV 13 NVColorado San Miguel 8 08 113 081130004 11 9 9 11 12 NV 16 NVColorado Weld Greeley, CO Denver-Aurora, CO 8 08 123 081230006 25 22 22 23 24 24 25 Colorado Weld Greeley, CO Denver-Aurora, CO 8 08 123 081230008 27 21 18 19 24 26 26 

24-hour Design Values 1 3 

2001-2003 2002-2004 2003-2005 State County CBSA CSA EPA Region ST COU Site 2004-2006 2005-2007 2006-2008 2007-2

Notes:1. In this table, all design values are calculated based on the rules specified in Appendix N for the 2012 PM2.5 NAAQS. The term "NV" denotes design values that are not valid in accordance with the 2012 NAAQS2. Monitoring sites with an annual deesign value status of 'X' hev been determined by EPA to represent unique microscale or middle scale locations are not used for comparison to the annual PM2.5 NAAQS. The 2012 revisions to 40 CFR 58 require a formal exclusion justification to be described in the annual State monitoring plan. 
3. For sites with approved seasonal sampling, the promulgated methodology may change the annual 98th 

percentile and 24-hour design value from the values posted on this website in previous years which were calculated under the 2006 NAAQS methodology. Data from 2011 and previous years processed using the 2006 rules can be found in the 2011 “PM2.5 Detailed Information” file posted here: http://www.epa.gov/airtrends/values.html. These changes in design values and corresponding changes in the trend are due to the new official calculation methodology and may not indicate a change in air quality observed for that area or location.3. For sites with approved seasonal sampling, the promulgated methodology may change the annual 98th percentile and 24-hour design value from the values posted on this website in previous years which were calculated under the 2006 NAAQS methodology. Data from 2011 and previous years processed using the 2006 rules can be found in the 2011 “PM2.5 Detailed Information” file posted here: http://www.epa.gov/airtrends/values.html. These changes in design values and corresponding changes in the trend are due to the new official calculation methodology and may not indicate a change in air quality