Ozone pollution improving in the U.S.

By: Dr. Jeff Masters , 7:03 PM GMT on May 01, 2007

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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

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188. weatherboykris
3:22 AM GMT on May 02, 2007
Learn to read a surface map,canewhisperer.The vertical line is the waveLink
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187. weatherboykris
3:22 AM GMT on May 02, 2007
Ivan had waves of 91ft.
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186. TheCaneWhisperer
3:19 AM GMT on May 02, 2007
This was interesting though, from the NHC!

LATEST GFS MODEL RUN DEVELOPS A WEAK LOW
OR TROUGH NE OF THE BAHAMAS BY THE END OF THE WEEK.
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185. weatherboykris
3:20 AM GMT on May 02, 2007
Posted By: Rodek at 3:20 AM GMT on May 02, 2007.

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.
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184. weatherboykris
3:18 AM GMT on May 02, 2007
Posted By: StoryOfTheCane at 2:50 AM GMT on May 02, 2007.

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.
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183. Rodek
3:14 AM GMT on May 02, 2007
I've heard mention of very large "rogue" waves being produced during hurricanes. Is there such a thing?
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182. kmanislander
3:11 AM GMT on May 02, 2007
good night all
Member Since: August 19, 2006 Posts: 0 Comments: 15842
181. kmanislander
3:02 AM GMT on May 02, 2007
Catch you tomorrow Bama

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.
Member Since: August 19, 2006 Posts: 0 Comments: 15842
180. Bamatracker
3:01 AM GMT on May 02, 2007
alright...i need to call it a night too. Good night all! keep it pornfree!!
Member Since: May 17, 2006 Posts: 6 Comments: 1367
179. TheCaneWhisperer
2:59 AM GMT on May 02, 2007
West Caribbean that is!
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178. TheCaneWhisperer
2:52 AM GMT on May 02, 2007
That is why storms don't form in the East and Central Atlantic until late July, high shear! The Bermuda high will not settle into place until early July! The Gulf of Mexico and Caribbean is where you need to be looking now. If these early waves hold together across the Atlantic, they may spark some interest in the west. It could be what the GFS was looking at yesterday!
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177. kmanislander
2:58 AM GMT on May 02, 2007
logic

no offense taken
the reference to porn was a little harsh though LOL
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175. kmanislander
2:54 AM GMT on May 02, 2007
High shear is the norm for this time of year. In fact water temps in the S Caribbean would support tropical systems all year were it not for the increase in shear come Nov through May/June. Some years have high shear most of the season and others the opposite.

We will have to wait and see how the season sets up
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174. Bamatracker
2:55 AM GMT on May 02, 2007
anybody have a windshear map that shows departure from avg.?
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173. kmanislander
2:53 AM GMT on May 02, 2007
good night to those who are leaving. Only 10 pm here LOL
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172. pottery
10:47 PM AST on May 01, 2007
I'm out too. It's 11;00 here man. Goodnight all.
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171. StoryOfTheCane
2:49 AM GMT on May 02, 2007
yeah, its just kinda weird to see the Highly Unfavorable shear almost surround the high at all angles
170. Bamatracker
2:47 AM GMT on May 02, 2007
i think this shear is normal around this time of year....maybe:/
Member Since: May 17, 2006 Posts: 6 Comments: 1367
169. weathermanwannabe
10:45 PM EDT on May 01, 2007
I know what you mean; my Wife is calling me right now ("get off the Blog and get to bed")...See everyone tommorow......
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168. StoryOfTheCane
2:45 AM GMT on May 02, 2007
is the High being so strong the reason for the excessive shear at the moment? this image kind of makes me think that.

167. kmanislander
2:41 AM GMT on May 02, 2007
logic

you have something else to talk about-- like global warming perhaps ??

or maybe politics ??

What gives. This is a weather blog
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166. Bamatracker
2:43 AM GMT on May 02, 2007
im addicted to weather.....gets me in trouble all the time lol!
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165. pottery
10:43 PM AST on May 01, 2007
Hi Tazmanian.
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164. Bamatracker
2:41 AM GMT on May 02, 2007
sshhh sotc....dont mention gw...dont want to get anyone riled up.
Member Since: May 17, 2006 Posts: 6 Comments: 1367
162. weathermanwannabe
10:39 PM EDT on May 01, 2007
Most of us are weather addicted; much more healthy than other forms of addiction.....
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161. pottery
10:36 PM AST on May 01, 2007
Logic, what brings you here, then ?
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160. Tazmanian
7:36 PM PDT on May 01, 2007
hello
Member Since: May 21, 2006 Posts: 5091 Comments: 115244
159. StoryOfTheCane
2:39 AM GMT on May 02, 2007
hey, a wave is better than the long global warming arguments, I say hype the wave all day lol
158. StoryOfTheCane
2:39 AM GMT on May 02, 2007
hey, a wave is better than the long global warming arguments, I say hype the wave all day lol
157. Patrap
9:39 PM CDT on May 01, 2007
7
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156. Bamatracker
2:37 AM GMT on May 02, 2007
well I wouldn't say porn.....but it is cool to watch all the different aspects that make up a conducive environment for development of hurricanes come together slowly over the month of May
Member Since: May 17, 2006 Posts: 6 Comments: 1367
155. weathermanwannabe
10:32 PM EDT on May 01, 2007
Awesome shot....What I notice is that there appears to be lot more moisture off the coast this year than last year...I guess the Saharan dust, which killed a few storms last year, will not play as big a factor this season?
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153. Bamatracker
2:35 AM GMT on May 02, 2007
Ana looked cool
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152. Levi32
6:35 PM AKDT on May 01, 2007
txag91met - Just give them a break. We're all anxious for the season to start lol.
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151. StoryOfTheCane
2:35 AM GMT on May 02, 2007
we could be about 20 days away if the shear forecast is right, txag91met, its not WAY too early at all, i would phrase it A LITTLE BIT early
150. StoryOfTheCane
2:34 AM GMT on May 02, 2007
i wonder what the shear was like when Anna formed, any way to find that out?
149. txag91met
2:31 AM GMT on May 02, 2007
Guys it is way too early! Wait until June.
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148. kmanislander
2:33 AM GMT on May 02, 2007
Anna did form on April 20 but not out in the deep Atlantic

Link
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147. Bamatracker
2:31 AM GMT on May 02, 2007
ooooooohhh....pretty big picture cane!
Member Since: May 17, 2006 Posts: 6 Comments: 1367
146. StoryOfTheCane
2:31 AM GMT on May 02, 2007
the season is rapidly approaching
145. TheCaneWhisperer
2:30 AM GMT on May 02, 2007
The Big Picture!
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144. pottery
10:26 PM AST on May 01, 2007
Yep, Kman, still bone-dry here as well. I was looking at those African showers too, they are a long way south, and maybe will encourage some showers here if they can make the crossing in one peice !
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143. Bamatracker
2:28 AM GMT on May 02, 2007
aaahhh...well as long as they die off. Hopefully we can keep the wind shear shield going around the u.s.
Member Since: May 17, 2006 Posts: 6 Comments: 1367
142. kmanislander
2:28 AM GMT on May 02, 2007
weatherman

good evening to you too
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141. kmanislander
2:25 AM GMT on May 02, 2007
Bama

It will die down because water temps are still too cool this early and they are coming off too far South to get the coriolis effect that spins them up into systems. It will be mid to late July before the Cape Verde season begins. However, the strength of waves coming off are an important signal for what the season may have in store
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140. StoryOfTheCane
2:23 AM GMT on May 02, 2007
wow, that shear forecast could be troublesome
139. Bamawatcher
9:24 PM CDT on May 01, 2007
Kman april 2003 Tropical Storm Ana.... like the 17-23 or something like that....not sure if it is the earliest, but it is earlier than this one

That is unless you are talking about the African coast only...Cause not sure where Ana was....LOL
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138. kmanislander
2:23 AM GMT on May 02, 2007
hi pottery

yeah we did have some cover but pics can be deceiving. You would think we had a shower or two but all day hot sun with a little overcast.
At least its a start
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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