High Desert Ends 2011 With 47% Drop In Ozone Exceedances

By Staff Reports

(Victorville)–High Desert residents will have plenty to celebrate as 2011 winds to a close, not the least of which is a 47% reduction in exceedances of the federal eight-hour ozone standard. According to preliminary data collected by the Mojave Desert Air Quality Management District, only 35 days exceeded the federal 0.075 parts per million federal health standard District wide as of mid-December 2011, as compared to 66 days by the same time last year.

Ground level ozone is the main component of photochemical smog and a strong irritant that can cause constriction of the airways. Children, the elderly and individuals with heart or lung  disease are particularly susceptible to the effects of smog, which can also increase symptoms for

individuals affected by asthma or bronchitis Victorville led the way in reductions , with only one day exceeding the federal eight-hour standard in 2011, compared to 20 days in 2010, for a dramatic 95% decline. The Phelan station – which along with the Hesperia site, historically records the highest number of federal ozone exceedances District wide – logged only 25 exceedances in 2011, compared to 53 in 2010. Hesperia’s federal exceedances days also dropped from 43 in 2010 to 26 in 2011.

Maximum ozone concentrations also dipped in 2011, with 0.10 ppm being the highest reading recorded this year in Victorville, as compared with a high of 0.11 ppm in 2010. Phelan topped out at 0.12 ppm in 2010 vs. 0.14 ppm in 2010. Similarly, the Hesperia station logged a high reading of 0.11 ppm in 2011, as compared to 0.12 ppm in 2010. While wildfires in the Cajon Pass and Oak Hills areas temporarily contributed to elevated particulate matter levels in areas downwind of the fires within the MDAQMD in late August andearly September, ozone levels – which are primarily influenced by stationary and vehicular source emissions – were largely unaffected by the smoke.

Cooler than normal temperatures during much of the High Desert’s 2011 ozone season – which spans between May and October-were largely responsible for the decline in ozone exceedance days this summer. Despite being the recipient of windblown transported pollutants originating in the Los Angeles basin, the MDAQMD has continued on a multi-decade trend toward cleaner air, a result of emission reduction efforts by regulated industry, less-polluting cars and trucks and improved gasoline and diesel formulas required in California.

“It’s always good to end the year breathing cleaner air than the year before,” commented MDAQMD Executive Director Eldon Heaston. “Despite the challenges of a growing population and tighter air quality standards, the High Desert’s air quality continues to progressively improve.”

The MDAQMD is the air pollution control agency for the High Desert portion of San Bernardino County and for the Palo Verde Valley in Riverside County. For real time air quality data or to sign up for email air quality alerts, visit the MDAQMD’s website at www.mdaqmd.ca.gov.

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