2018 Air Quality Status

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 Environmental Protection Agency's (EPA's) 2015 National Ambient Air Quality Standard (NAAQS)
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, which are located at Calaveras Lake, Camp Bullis, and Marshall High School (referred to as San Antonio NW). In order to be in compliance with the standard, the three year average must be no higher than 70 parts per billion (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 2018 Ozone Season (which began March 1 and will end on November 30, 2018):

Table 1:  Four highest ozone readings of 2018 at regulatory monitoring sites (as of 5/21/18)
Monitoring Site  Highest  ppb  2nd Highest  ppb  3rd Highest  ppb  4th Highest  ppb
San Antonio NW C23  05/07/18   75 04/23/18  73 04/28/18  69  04/24/18  67
Camp Bullis C58 05/07/18  83      04/23/18  77 04/24/18   73 04/28/18  72
Calaveras Lake C59      05/07/18  71      05/06/18  71      04/28/18   68      04/24/18  66
Source: https://www.tceq.texas.gov/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 67 ppb, 72 ppb, and 66 ppb, respectively as of May 21, 2018.  When those fourth highest readings are averaged with the fourth highest readings from 2016 and 2017, and demonstrated in Table 2, below, the three year averages are 70 ppb at San Antonio Northwest, 71 ppb at Camp Bullis, and 64 at Calaveras Lake:

Table 2: 2016-2018 3-year average of 4th highest, 8-hour reading at regulatory monitoring sites (as of 5/21/18)            
Monitoring Site     2016     2017     2018  3-Yr Average
San Antonio Northwest C23 71  73 67  70
Camp Bullis C58       69        72        72           71
Calaveras Lake C59       62        65        66           64






Source: https://www.tceq.texas.gov/cgi-bin/compliance/monops/8hr_attainment.pl

Although the 2018 readings have yet to be confirmed by the Texas Commission on Environmental Quality, it appears that our three-year average is exceeding the standard for ground level ozone at one of the region's regulatory monitors. The three-year average of the fourth highest, eight-hour reading at Camp Bullis is 71 ppb for the years 2016 through 2018. 
 
Monitor readings since 2012 have indicated that San Antonio area has been out of compliance with the federal ozone standards, even though, before 2015, the standard threshold had been set at a more lenient 75 ppb compared with the current 70 ppb threshold. 

For all areas except Bexar County, the EPA has completed the process of designating areas of nonattainment and placing them into six possible categories, according to the level of the areas' standard violation, from marginal to severe.  Each of these categories have progressively stricter regulations designed to reduce pollution and bring them back into compliance with the federal standards.  It expects to designate Bexar County's air quality status by July, 2018.

Because the San Antonio area has been in noncompliance for the evaluative years of 2014 through 2016 and was also in noncompliance for the years 2015 through 2017, it is likely that Bexar County 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, 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.