Ozone pollution improving in the U.S.
Air pollution season is here, and the good news is that ozone pollution in 2006 was considerably better than in previous years. Along with pollution due to small particles (particulate matter), ground-level ozone is the most serious pollutant in the U.S. Ozone levels in 2006 showed improvement in 23 out of 35 of the major cities in the U.S. (Figure 1) compared to 2005, and was at or below the 10-year average in all but five cities. Atlanta, Georgia, showed the greatest jump in the number of unhealthy days, from 17 in 2005 to 30 days in 2006; however, this number was still below the 10-year average. Many western cities reached levels at or above the 10-year average, including San Diego, Sacramento, Denver, and Las Vegas. This was in part due to much above average summertime temperatures in the western U.S. (Figure 2). Los Angeles had the worst ozone pollution in the U.S., with 46 unhealthy days. Los Angeles also was the most polluted city overall in 2006, according to the American Lung Association. However, Los Angeles' bad ozone days declined by 16% in 2006 compared to 2005.
Figure 1. The number of days in May through September of 2005 and 2006 in which ground-level ozone reached Unhealthy for Sensitive Groups--an Air Quality Index (AQI) above 100. Corresponding 10-year averages are also shown. Image credit: EPA.
Ozone pollution has improved
Is the improvement seen in ozone levels in 2006 merely due to a lack of meteorological conditions that favor air pollution? To check, I've plotted the difference in surface temperature (degrees C) from May-September 2006, compared to the 10-year average from 1995-2005 (Figure 2). The chemical reactions that form ozone are most efficient at high temperatures, so if the summer of 2006 was cooler than usual, we'd expect a drop in ozone levels. However, the summer of 2006 was the second warmest in U.S. history--but ozone levels still dropped. All of the cities where ozone increased significantly in 2006 over 2005 levels were areas where temperatures were above average. Los Angeles had summer temperatures more than 1 degree C above normal, yet still recorded a drop in ozone, suggesting that strategies to control ozone pollution there are paying dividends. In fact, new rules to limit nitrogen oxide emissions from power plants have been enacted nation-wide in the past few years, and the ozone pollution statistics from 2006 are evidence that these emissions rules are working. Ozone pollution since 1980 has dropped 21% (Figure 3), despite the fact that the average summer temperatures have generally been increasing.
Figure 2. The difference in surface temperature (degrees C) from May-September 2006, compared to the 10-year average from 1995-2005. Temperatures were above the 10-year average across most of the country, except for New Mexico, and portions of the Ohio Valley surrounding Kentucky. Image credit: NCAR/NCEP.
Figure 3. Trends in ozone air pollution in the U.S. (white line) and uncertainty (blue areas, marking the standard deviation). The federal standard of 0.08 ppm is indicated by the dashed line. Since 1980, maximum ozone levels have declined 21%. Since 1990, the decline has been 9%. Note that the lowest ozone levels were recorded in 2004, which was an exceptionally cool summer across most of the U.S. Image credit: U.S. EPA.
Next blog (Thursday): Pollution costs and deaths exceed the impact of a new Hurricane Katrina hitting the U.S. each year.
Jeff Masters
Reader Comments
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you have something else to talk about-- like global warming perhaps ??
or maybe politics ??
What gives. This is a weather blog
We will have to wait and see how the season sets up
no offense taken
the reference to porn was a little harsh though LOL
I just looked for a wind shear anomaly map but did not find one. Certain times of year have higher shear than others and this is still high shear time. Several factors come into play to determine shear levels and they are seasonal in nature like the jet stream location, troughs and how far South they dig, the TUTT location etc.
yeah, its just kinda weird to see the Highly Unfavorable shear almost surround the high at all angles
Not unusual at all.I remember this time last year it was just as high or higher.Perfectly normal.
I've heard mention of very large "rogue" waves being produced during hurricanes. Is there such a thing?
Yes...wait a moment for more info.
LATEST GFS MODEL RUN DEVELOPS A WEAK LOW
OR TROUGH NE OF THE BAHAMAS BY THE END OF THE WEEK.
high shear/relatively low SST's = no invest!
But after last year, even a blob is exciting! LOL
2006..... the year of weak multiple vortice storms! (sp?)
multiple Vorti? LOL
Just tell me where the wave is verified here?
...ITCZ...
ITCZ AXIS IS CENTERED ALONG 7N12W 4N20W 3N30W CROSSING THE
EQUATOR AT 40W INTO NE BRAZIL NEAR 2N47W. THE LARGEST
CONCENTRATION OF CONVECTION NEAR THE ITCZ IS ASSOCIATED WITH A
TROUGH THAT IS ALONG 23/24W ON THE 18Z SURFACE MAP. DURING THE
LAST FEW HOURS...THE STRONG CONVECTION ASSOCIATED WITH THIS
TROUGH HAS DIMINISHED A BIT. THIS AREA OF CONVECTION CAME OFF
THE AFRICAN COAST TWO DAYS AGO AND HAS BEEN MOVING WWD SHOWING
SOME TROPICAL WAVE-LIKE CHARACTERISTICS. AS THE DAY WORE ON...A
DRIFTING BUOY LOCATED NEAR 23W SHOWED A WIND SHIFT FROM NE TO SE
WITH THE TROUGH PASSAGE. SCATTERED MODERATE CONVECTION IS FOUND
AHEAD OF THE TROUGH AXIS FROM EQ-5N BETWEEN 25W-32W. ANOTHER
CLUSTER OF STRONG CONVECTION IS INLAND OVER AFRICA APPROACHING
THE PRIME MERIDIAN.
You called me Levi.
LOL
No offense weatherboykris
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