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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 will continue through October) as of September 18, 2016:

Table 1:  Four highest ozone readings of 2016 at regulatory monitoring sites (as of 09/18/16)
Monitoring Site

Highest Reading

 ppb

2nd Highest

 ppb

3rd Highest

 ppb

4th Highest

 ppb
San Antonio NW C23 05/05/16 

73

05/06/16

71

04/23/16

69

04/08/16

66

Camp Bullis C58 05/06/16

69

04/23/16

67

04/08/16

64

04/05/16

63

Calaveras Lake C59

05/06/16

67

 04/22/16

62

04/08/16

61

06/29/16

  60
Source:  http://www.tceq.state.tx.us/cgi-bin/compliance/monops/8hr_4highest.pl

Table 1 shows that (as of 09/18/16) the fourth highest, eight-hour average reading at the three regulatory monitors in the region, San Antonio Northwest, Camp Bullis, and Calaveras Lake, were 66 ppb, 63 ppb, and 60 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 71 ppb at San Antonio Northwest, 71 ppb at Camp Bullis, and 63 at Calaveras Lake:

Table 2: 2014-2016 3-year average of 4th highest, 8-hour reading at regulatory monitoring sites (as of 09/18/16) 
Monitoring Site

2014

2015

2016

3-Yr Average

San Antonio Northwest C23 69  79 66 71
Camp Bullis C58

72

 80

63

71

Calaveras Lake C59

63

 68

60

63

Source:  http://www.tceq.state.tx.us/cgi-bin/compliance/monops/8hr_attainment.pl

While the 2015 readings are yet to be confirmed by the Texas Commission on Environmental Quality, it is apparent that, although the 2015 Ozone Season will not be over until November, our three-year average has already 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.