Ozone Update

Ben WellsU.S. Environmental Protection Agency

Office of Air Quality Planning and StandardsAir Quality Analysis Group

February 11, 2014

2

Overview

• Past: Ozone data through 2012– 2012 ozone trends and design values– Influence of meteorology

• Present: Preliminary 2013 data– Preview of 2013 ozone data– Public data access tools

• Future: 2013 design values and trends updates

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Ozone Trend, 2000 - 2012

• The national average of the annual 4th highest concentrations:– Decreased by 9% from 2000 to 2012– Decreased by 21% from 2002 to 2009– Increased by 8% from 2009 to 2012

90th Percentile

50th Percentile

10th Percentile

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Change in 8-hour Ozone Design Values

2009-2011 to 2010-2012Average increase of 2.0 ppb

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Influence of Meteorology on Ozone• Ozone tends to be highest on hot, dry days with calm or light winds• Meteorological conditions are more favorable toward ozone formation in some

years than in others• EPA uses a statistical model to “adjust” seasonal average ozone trends to remove

effects due to meteorological variability

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Influence of Meteorology on Ozone

(< 60 ppb) (60 – 75 ppb)

(76 – 95 ppb) (96 – 115 ppb) (> 115 ppb)

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Meteorology: 2012 vs. 2013Source: National Climatic Data Center (http://www.ncdc.noaa.gov/)

Tem

pera

ture

Prec

ipita

tion

April – September 2012 April – September 2013

← Cooler Average Warmer →

← Drier Average Wetter →

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Average decrease of 5.2 ppb

Change in May - September Mean8-hour Ozone Values, 2012 to 2013

(2013 values based on preliminary data)

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Change in Annual 4th Highest 8-hour Ozone Values, 2012 to 2013

(2013 values based on preliminary data)

Average decrease of 7.2 ppb

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• AirData: http://www.epa.gov/airdata/ – Download daily air quality concentration data or annual

summary statistics for any monitor or geographic area– Several visualization tools for generating downloadable

graphics based on air quality concentration data– Provides the latest data available in EPA’s AQS database

• AirTrends: http://www.epa.gov/airtrends/ – View or download trends in EPA’s six criteria pollutants,

nationally, regionally, and locally– Download official design values for EPA’s six criteria

pollutants– Updated annually by AQAG (August)

Public Data Access Tools

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2013 Design Values and Trends Updates

• May 1, 2014 – Deadline for 2013 air quality data certification in AQS

• May – AQAG retrieves data from AQS and generates draft 2013 design value tables

• June – EPA regional office review of draft design values

• Late June/early July – AQAG retrieves data from AQS for final design values and trends

• July/August – AQAG generates final 2013 design value tables and updates trends information

• August 2014 – AQAG updates the AirTrends webpage

? ? ? Questions ? ? ?