Chicago has faced a bit of criticism for its groundbreaking and controversial plan to tear down its collection of dated and dangerous high-rise public housing properties and replace them with lower-density, mixed-income housing built by private developers.

But now its efforts are being challenged for health reasons–specifically, the impact of its demolition activities on nearby air quality. In July, the University of Illinois at Chicago released a study saying that air quality samples obtained at three high-rises–Robert Taylor Homes, Stateway Gardens, and ABLA Homes–showed a 59 percent increase in outdoor particulate matter around the demolition sites. Larger increases occurred closer to these locations. All three sites were within 100 meters of occupied public housing structures and within 250 meters of a school or other community buildings.

The demolition of Chicago's public housing left very high level of coarse particles in the air.
Chicago Housing Authority The demolition of Chicago's public housing left very high level of coarse particles in the air.

"The air quality is worse during demolition," says Samuel Dorevitch, research assistant professor at the university's School of Public Health. "On days you can see dust, it's considerably higher still. If you look at demolition versus pre-demolition, there's about a 25 percent increase in the coarse particles during demolition."

Instead of using implosion to destroy the buildings, CHA's contractors demolish them with heavy equipment over a period of weeks. The two methods create substantial differences in air quality–and demolition is actually the cleaner route. "With demolition by heavy equipment, it takes weeks for air quality to get back to normal," Dorevitch says. "The air quality never gets quite as bad [as implosion], but it has a sustained low-level increase [in particulant matter] that goes on for weeks."

Either way, bad air quality isn't good for people who live in the surrounding areas, especially minority, low-income communities, which the university says have higher rates of asthma. "In general, particulant matter has a negative affect on health," Dorevitch says. "It worsens asthma. It can lead to more frequent emergency room visits and problems with lung function."

CHA maintains that the high-rises were a public health hazard before coming down and that it is taking appropriate precautions. The agency hires environmental consultants to monitor air around the building during demolition activity. It also has air-monitoring stations located upwind, downwind, and at sensitive receptors and says its air-sampling results continue to be below the Environmental Protection Agency's regulated standards. CHA contends that its samples have met these standards.

Dorevitch says that people should still be concerned. He argues that while the particulate matter concentrations at the projects averaged over 24 hours did not exceed EPA standards, short-term increases can prove to be very harmful. Though CHA's contractors used heavy equipment to destroy the buildings (versus implosion), the short-term peaks in particulant matter was still higher than the 24-hour averages

"When we looked at very short-time intervals, we found extremely high levels downwind of the demolition sites," Dorevitch says. "The health effects of short-term exposure have not been well described. We know what an average 24-hour air pollution concentration can do to health, but we don't know what it means if somebody is exposed to a level 10 times the EPA standards over a very short time period."

CHA says it is taking proper steps to protect people's health. "To ensure the health and safety of our residents, the CHA strictly enforces watering the building being demolished and spraying water on [the] debris stockpile," says Karen Pride, spokeswoman for the agency. "Multiple hoses are used for this activity, which is monitored by field staff and consultants." –Les Shaver