1. Department of Environmental Quality
2015 Ozone Standard Update
Air Quality Committee Meeting
July 13, 2016
Donnie Redmond
Department of Environmental Quality

2. 2015 Ozone Standard Update - Data Evaluation and Upcoming Designation Process
New ozone standard
New data handling method to determine compliance
Current status

3. North Carolina’s Primary State Plan Approach

4. Ozone NAAQS Review
On 10/1/15 EPA announced new primary and secondary standards 70 ppb
State recommendations for boundary designations due October 2016 based on data or preliminary data
EPA designations to be finalized in October 2017
Currently all monitors in North Carolina are measuring compliance with the new standard

5. How to determine compliance?
Ozone concentrations are constantly measured, averaged over an hour
Determine the maximum 8-hour concentration each day
An “exceedance” is a daily 8-hour value > 70ppb
Determine the 4th highest daily value each year
Average together three years
A “violation” is a 3-year average > 70ppb
We requested a change in the new rule that impacted this process

6. About that 8-hour maximum (old way)
Look at each 8-hour period of the day
Midnight – 8am
1am – 9am …
11pm – 7am (the next day)
Gives you 24 of these 8-hour values
For each day, determine the maximum 8-hour average
This method allows double-counting
A single event (e.g., 1am-4am on Tuesday) that occurred early morning would count twice
10:00pm – 6am, Monday
1:00am - 9am, Tuesday
This could be a big deal when you’re looking for 4th highest and a single event was doubled-counted

7. Determine the 8-hour maximum
Typically, double-counting is not a problem
Highest ozone values are generally in the afternoon
Exception is overnight ozone transport at high- elevation sites
New method
First 8-hour period is 7am-3pm; last one is 11pm-7am
17 periods in a day
Covers all 24 hours without double-counting

8. How is 2016 looking?
Recent exceedances of the 2008 ozone standard (no violations)
1 in 2013
0 in 2014
5 in 2015
We’ve already had 28 exceedances this year (thru June 12)
Only 5 would have exceeded the old standard (75 ppb)
We’re not in trouble yet, but it’s something to watch
“Exceedance” is a daily 8-hour average >70 ppb
“Violation” is a three-year average >70 ppb
A single bad day will not “violate” the standard

9. How is 2016 looking? (cont.)
Highest design value in NC is the 68 ppb at Garinger (Charlotte)
Would need a 4th highest value of 75 ppb to violate the standard
4th highest is currently 70 ppb
Highest 4th 8-hour average in 2016 is 70 ppb at Mt. Mitchell
Will need a 4th highest value of 88 ppb in 2016 to “violate” the standard for at this site

10. Questions? Donnie Redmond Ambient Monitoring Section Chief
Department of Environmental Quality