Blazing hot weather, with temperatures in the high 90s, continued to roast the Chicago area Saturday, but the high ozone levels that had blanketed the city with smog for a week declined for a second day to safe levels.
Saturday`s high was 97 degrees, just one degree short of the record. However, ozone levels throughout the city and suburbs fell to less than 100 parts per billion, below the 120 p.p.b. warning level.
Slightly cooler weather was predicted for Sunday, along with scattered evening thundershowers.
Forecasters said temperatures in the 70s and 80s were expected early this week, providing relief from the hot, humid, smoggy weather that plagued Chicago most of last week, adding to a summer already filled with
environmental threats.
Saturday`s heat also kept the crowd down to an estimated 240,000 at the Taste of Chicago during the day, though thousands turned out at night for a concert by singer Stevie Wonder at the Petrillo Music Shell.
During the concert, several people were slightly injured in a human stampede set off by firecrackers that were mistaken for gunshots, police said. The concert was not disrupted.
While thousands fled from the band shell area onto Jackson Drive, police moved in on horseback to slow the surge and right toppled fences, witnesses said.
Northwestern Memorial Hospital treated more than 10 people who received minor injuries, and several more were being treated on the scene, said Gretchen Flock, a hospital spokeswoman.
”Some nitwit threw a firecracker, and people thought it was gunshots,”
said Chicago Police Lt. Charles Mandel. ”It was wall to wall people, and thousands of them just ran when they heard it.”
Earlier in the day, vendors reported slow sales due to the smaller crowds.
”The heat is really hurting us,” said Carl Parker, manager of the Haagen-Dazs ice cream booth. ”I guess everyone`s just waiting for the sun to go down.”
”It`s been kind of slow today,” said Jean Lee, owner of the Guey Lon restaurant. ”When it gets this hot people don`t tend to eat. They tend to drink and eat little finger foods.”
”I certainly haven`t eaten as much as usual because it`s just too hot,” said Juda Haley of Waukegan. She said she had spent most of her Taste tickets on fruit drinks.
Taste organizers had to change the festival`s food tickets from yellow to green because imitation tickets were being reproduced from the originals. Those who still had yellow tickets could exchange them at the ticket booths for the new tickets, said Margaret Jones, director for the Mayor`s Office of Special Events.
Saturday`s hot weather snapped the power lines just south of a suburban rail station in Homewood, trapping more than 100 people on two Illinois Central Gulf trains without air conditioning and causing delays throughout the day.
”This heat is causing the wires to sag, and with the heavy winds the trains just clipped them,” said Joyce McDonald, Metra`s department head for external affairs, who said repairs were completed by the afternoon.
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While forecasts of scattered thunderstorms Sunday brought hope of the first rainfall in the Chicago area since June 29, they held little promise of providing the sustained rainfall needed to check the drought.
”They will be the kind of storms where you might be getting soaked while the guy standing next to you stays dry,” said Geoff O`Toole, a meteorologist with the Central Weather Service.
The 9.64 inches of rain that had fallen by June 30 in Chicago was far short of the normal 16.39 inches. Forecasters predict that July, which had brought no rain up to Sunday, will be hotter than average and will fall shy of its normal contribution of 3.63 inches of rain.
As water levels drop in Lake Michigan and the banks of the Mississippi River grow wider, the farmers in between are watching the drought boost evaporation rates in their fields and endanger the livestock and poultry in their barns, according to the National Weather Service.
Meanwhile, ozone may increase to dangerous levels again as hot conditions return at the end of the week.
The highest ozone levels seen in Chicago in a decade enveloped the city in a blanket of haze last week, obscuring the skyline and leaving joggers, the elderly and those suffering from lung ailments gasping for breath.
Ozone has a bit of a Jekyll and Hyde personality. In the upper atmosphere, a blanket of it blocks the sun`s harmful ultraviolet rays, which can cause skin cancer and cataracts. But when even tiny amounts are created in the lower atmosphere from chemicals in auto exhaust and other pollutants, the compound causes symptoms ranging from eye irritation to serious breathing problems.
Ozone is formed when hydrocarbons and nitrogen oxide react in the presence of sunlight. Usually the component chemicals, rising from morning rush hour exhaust and from factories, ”bake” gradually over the day, producing more and more ozone, according to Christian Rice, a spokesman for the U.S. Environmental Protection Agency. Levels usually peak in the late afternoon or early evening, if they are not swept away by wind or rain.
In contrast, emissions produced during the evening rush hour create much less ozone, because the sunlight is fading later in the day, Rice said.
Sunlight, in fact, is the main factor necessary for the production of ozone. Heat and humidity also can speed the process, and still weather conditions help keep ozone, once it is created, in the area, experts say.
Though the chemicals that produce ozone come from a wide variety of sources, including dry cleaners, auto paint shops, underarm deodorants, household cleaners, oil-based paints and gas stations, where gasoline fumes leak during refueling, automobiles and industry continue to be the major source of the pollutants.
Automotive emissions, in particular, are on the increase, skewing the EPA`s estimates, made a decade ago, of how serious the ozone problem would be now in cities.
”Between 1976 and 1985, vehicle miles traveled increased 30 percent,”
Rice said. ”That`s an incredible increase. If we targeted our programs to deal with the 1976 problem, we were 30 percent off just on autos alone.”
Efforts to decrease the amount of ozone-forming chemicals emitted by autos mean not only facing resistance from the auto industry, which already has reduced emissions in most cars, but also ”coming up against the American driver,” who has resisted calls to drive less or submit to emission inspection programs, he said.
Earlier warnings of the health dangers from ozone also are proving inadequate, Rice said, as new research shows that low levels of ozone, once considered safe, may be causing long-term lung damage.
Ozone, when it enters the lungs, lands on the mucuous membranes, forcing them to produce more protective mucus. Inflammation eventually results and can lead to scarring of the alveoli, tiny sacs where oxygen enters the bloodstream. As they scar, they harden and can no longer expand and contract as well, according to Dr. David Cugell, a lung disease specialist at Northwestern Memorial Hospital.
The hardening of alveoli had been considered temporary and associated only with short exposure to high levels of ozone. But the new research suggests that longer-term exposure to ozone, even at levels below the federal health standard of 120 parts per billion, may lead to impaired air exchange and premature aging of the lungs, according to a report in the June 24 edition of Science magazine.
As a result, some scientists and federal officials are seeking to have the accepted safety level for ozone lowered to 80 parts per billion.
”The stakes have been significantly raised in the last several years on ozone,” said Rice of the EPA. ”We have a heck of a problem.”