2016 Air Quality Status

On April 8, 2016, the eight-hour average ozone reading at San Antonio's Camp Bullis monitor was 61 parts per billion (ppb).  As of April 8, this reading was the fourth highest of the year.  When that reading is combined with fourth-highest readings from the 2014 and 2015 at the Camp Bullis monitor, the average was 61 ppb.  That average was high enough to render the area noncompliant with  the Environmental Protection Agency's (EPA's) 2015 National Ambient Air Quality Standards (NAAQS), which is set at a 70 ppb average of fourth-highest readings over a 3 year period. 

Ground-level ozone forms when nitrogen oxides (such as those found in vehicle exhaust) combine with volatile organic compounds (such as those found in gasoline fumes) during periods of intense sunlight. Ozone is the most prevalent form of air pollution in the Alamo region.  Attainment of the federal standard for ground-level ozone is based on a three-year average of the annual fourth highest, eight-hour reading at any one of the area’s three regulatory monitors. In order to remain in compliance with the standard, the three year average must be no higher than 70 ppb.

Table 1 below lists the four highest daily maximum eight-hour ozone concentrations measured at the area's three regulatory monitoring sites during the 2016 Ozone Season (which began April 1 and ended October 31, 2016):

Table 1:  Four highest ozone readings of 2016 at regulatory monitoring sites
Monitoring Site  Highest Reading  ppb  2nd Highest  ppb  3rd Highest  ppb  4th Highest  ppb
San Antonio NW C23 10/02/16   76 05/05/16  73 10/11/16  72  05/06/16  71
Camp Bullis C58 10/11/16  81  10/02/16  74 10/03/16   70 05/06/16  69
Calaveras Lake C59       09/28/16  71   05/06/16  67      09/29/16   62      04/22/16  62
Source:  http://www.tceq.state.tx.us/cgi-bin/compliance/monops/8hr_4highest.pl

Table 1 shows that the fourth highest, eight-hour average reading at the three regulatory monitors in the region, San Antonio Northwest, Camp Bullis, and Calaveras Lake, were 71 ppb, 69 ppb, and 62 ppb, respectively.  When those fourth highest readings are averaged with the fourth highest readings from 2014 and 2015, and demonstrated in Table 2, below, the three year averages are 73 ppb at San Antonio Northwest, 73 ppb at Camp Bullis, and 64 at Calaveras Lake:

Table 2: 2014-2016 3-year average of 4th highest, 8-hour reading at regulatory monitoring sites                
Monitoring Site     2014     2015     2016  3-Yr Average
San Antonio Northwest C23 69  79 71 73
Camp Bullis C58       72        80        69           73
Calaveras Lake C59       63        68        62           64


While the 2016 readings are yet to be confirmed by the Texas Commission on Environmental Quality, it is nevertheless apparent that our three-year average has exceeded the standard for ground level ozone at two of the region's regulatory monitors; San Antonio Northwest and Camp Bullis.  At 71 ppb, this three year average is above the current standard threshold of 70 ppb.

This year marks the fourth year in a row--since 2012--that the San Antonio area has been out of compliance with the federal ozone standards, even though, until last year, the standard threshold had been set at a more lenient 75 ppb compared with the current 70 ppb threshold. 

Next year, the EPA expects to designate areas of nonattainment and place them into six possible categories, according to the level of the areas' standard violation, from marginal to severe.  Each of these categories will have progressively stricter regulations designed to reduce pollution and bring them back into compliance with the federal standards. 

The San Antonio area is clearly in noncompliance for the current evaluative years of 2014 through 2016 and it is likely that it will be required to meet some regulations.  If the area is designated nonattainment at the marginal level, for example, new or expanding manufacturers may be required to secure pollution reductions to offset their proposed growth, and transportation planners may be required to demonstrate that adding capacity to the roadway system would not increase pollution from cars and trucks in order to qualify for federal highway funds for roadway improvements.

Through its efforts to keep pollution at a minimum throughout the rest of the ozone season, however, the San Antonio area may be able to avoid the more stringent restrictions associated with a designation of nonattainment at the moderate level, which would bring additional, more stringent requirements, such as mandatory vehicle emissions testing.