Ozone chasers have a very busy summer

Ozone chasers have a very busy summer

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by joseph a. scolaro

photo by Charles S. Vallone

cutline: Maike Cxysz, a lane inspector at the emission testing station on Melvin Ave., checks the exhaust fumes of vehicle, Cars must meet certain emission standards to be liscensed.

Ozone carried by summertime winds clusters over Lake Michigan, a mass of unstable molecules on the brink of spilling into shoreline communities.

The amount of ozone hovering over cities like Racine, situated along the lake's shores, depends on the everchanging air currents. With a strong enough breeze off the lake, ozone levels can shoot up to dangerous levels.

Far above, in the upper reaches of the atmosphere called the stratosphere, ozone plays an important role for life, filtering out hot, ultraviolet rays from the sun.

But in the lower atmosphere, in the air we breathe, ozone can be dangerous - even deadly for people with respiratory problems..

This hot and muggy summer, the ozone winds have focused on southern Kenosha, northern Indiana and western Michigan, although all communities along the lake have seen high ozone levels at times.

State measurements show Racine had an average daily peak ozone concentration of 64 parts per billion of air, or ppb, through the summer months of June, July and August.

The federal Environmental Protection Agency considers 120 ppb of ozone an unhealthy level and worthy of an ozone advisory. Racine reached 113 ppb on July 30 and 31.

At Chiwaukee Prairie, in the southeastern corner of Kenosha County, and in in Carol Beach, ozone measurements reached some of the highest concentrations in the entire Lake Michigan region.

Chiwaukee Prairie's average peak ozone concentration for the summer was 76 ppb. Measurements reached 129 ppb July 30 and 127 ppb June 17.

In fact, the June 17 measurement violated an EPA rule and dashed any hopes of the state ridding itself next year of EPA pollution regulations, such as the mandated use of reformulated gasoline.

But don't blame the folks living near Chiwaukee Prairie.

Ozone is carried by wind currents from all around the country, and

states track the movements of ozone like zoologists monitoring migrating birds.

In Wisconsin, ozone chasers at the Department of Natural Resources gather recordings from air quality monitoring sites up and down Lake Michigan's shoreline.

"With ozone, it's like a bubble of air moving with the wind," DNR air specialist Craig Rendahl said. "Ozone is coming from all over. That's why the weather forecast is so important. We want to know where the winds are coming from."

Racine's monitoring site is located at 1519 Washington Ave. The recording device, as seen from the side of the building, looks like an upside down vacuum cleaner with a funnel at the end.

One may think living next to big Lake Michigan would help keep ozone levels down, but, in fact, the lake acts as a holding area for ozone.

As ozone is carried over the lake, it gets trapped in cooler air, which is situated over the lake like an invisible dome. The cool air gets sealed off from warmer air over land, Rendahl said.

Aircraft flying over the lake have recorded ozone concentrations greater than 200 ppb.

Warmer breezes blow over the lake's cool air, so the ozone just sits and builds up over the lake. When a strong wind blows off the water, a shoreline community can suddenly see a large increase in ozone.

This summer saw mostly winds blowing to the northeast, and communities along Michigan's western shoreline saw higher peak ozone averages. Pollution from the Chicago and Milwaukee areas also contributed to Michigan's higher ozone levels, Rendahl said.

On July 13, Holland, Mich., recorded a peak 178 ppb, and Muskegon, Mich., recorded a peak 171 ppb.

This year, Michigan City, Ind., had the highest average peak ozone concentration at 83 ppb. The city recorded a peak 154 ppb July 15. Chiwaukee had the second highest average.

Rendahl said pressure systems moving northwest brought ozone to Michigan City and then to Chiwaukee Prairie, carrying ozone and pollutants from the Ohio River Valley.

By monitoring winds, states can issue ozone advisories and Ozone Action Days.

For example, if higher ozone levels are recorded in southern Illinois, near St. Louis, and winds are blowing north, the DNR in Wisconsin might issue an Ozone Action Day, anticipating the ozone moving north the next day.

New this year for the Lake Michigan region were Ozone Action Days. When declared, people were supposed to cut down on activities that emit ozone-making pollutants, such as fueling a car.

States declared the days when they knew ozone would be breezing into their boundaries.

However, ozone can be tricky.

"July 12, that was the weirdest day of my career," Rendahl said. "The ozone didn't come from the lake. I don't know where it came from yet."

On that day, at the inland city of Appleton, a peak ozone level was recorded at 126 ppb, the first time in 12 years the city went over the EPA's ozone standard.

The month of August has been unpredictable.

Some have questioned why Ozone Action Days haven't been called often in August, despite the hot, humid weather.

"We've had unstable weather patterns," Rendahl said. "It's been hit and miss with the weather. We were paying attention and having a lot of tense moments as to whether we should call Ozone Action Days."

High temperatures and humidity doesn't always mean a higher ozone level, although that's usually a good indicator.

Rendahl said it will be difficult to gauge how Ozone Action Days affect the ozone level, but every bit helps.

In Racine, the bus service is free on Ozone Action Days until noon, but little change in ridership was noticed on those days, city Transit Planner Mike Glasheen said.

Area companies make an effort on Ozone Action Days.

For example, Racine's S.C. Johnson & Son Inc. fuels its fleet vehicles the nigh before an Ozone Action Day and tells its lawn services to not work that day, said Greg Anderegg, manager of community relations worldwide.

In addition, the company encourages its employees to reduce emissions by car pooling to work, he said. So the company runs a shuttle bus between its Sturtevant plant and its Racine headquarters on Ozone Action Days.

In the Lake Michigan region, Ozone Action Days were declared 10 times in June, six times in July and three times in August. Wisconsin was more often than not included in those declarations.

The DNR has been monitoring ozone since 1973. No major trends have yet been concluded. Measurements are taken April 15 to Oct. 15.


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