all Joel Schwartz stories

Dust from Asia invades North America

70652986 — Mon, 26 Mar 2007 06:28:24 -0400

On the dustiest days in the western United States, 40 percent of the grime blows in from Asia. And fine particles can travel all the way around the world from Africa's Sahara Desert. These unwanted visitors show up in a new model of dust imports developed by researchers from Harvard and the National Aeronautics and Space Administration (NASA). The findings have important implications for air pollution and climate change.

The Asian dust invasion is heaviest in the western states in spring. It moves on into the eastern U.S., but in much lower quantities. The traveling grime is mobilized by strong winds blowing over deserts or dry lakes and streambeds. "Most of the dust is from natural sources and falls out close to its source," notes Daniel Jacob, a professor of atmospheric chemistry and environmental engineering at Harvard. "But fine dust can be transported over long distances: from Asia to North America, and from North Africa to Florida, and all the way around the world to Canada and the U.S."

The grit is a health problem. A study done by other investigators, at the Harvard School of Public Health, concludes that an increase of particulate air pollution increases the risk of early death for people with diabetes, chronic obstructive lung disease, congestive heart failure, and inflammatory ailments like rheumatoid arthritis and lupus. Fine mineral dust is so damaging because it can penetrate much deeper into the lungs than larger particles.

Jacob worked with graduate student T. Duncan Fairlie and research associate Rokjin Park to build a computer model for estimating the impact of dust from Asia. They tested the model's accuracy with measurements from a NASA aircraft mission over the Pacific led by Jacob in 2001. The results were compared with dust records from Japan, various Pacific Islands, and air quality observing stations in the United States.

The model simulates the highs and lows of dust flow. Following the largest flow in spring, things quiet down in summer. Then a second, less active peak blows dust around in the fall. Winter is quiet.

North African dust imports peak during summer months in Florida and along the Gulf Coast. It adds haze in the Great Smoky Mountains, the Appalachians, and other East Coast locations.

Powerful mutagen found in Massachusetts water

70652986 — Mon, 26 Mar 2007 05:19:16 -0400

Mutagen X, a by-product of chemicals used to disinfect public water supplies, is not monitored or regulated in the U.S. water supply. A new report from researchers at Harvard's School of Public Health provides the first broad evidence that Mutagen X, first discovered in Finland's drinking water more than ten years ago, also lurks in chlorinated U.S. drinking water. Researchers discovered small amounts of Mutagen X, which is a powerful genetic mutation-causing agent, in 36 Massachusetts towns served by 23 different public water systems. The findings may increase support for pending national regulations to tighten drinking water standards and refuel local efforts to identify safer ways to disinfect tap water.

Air pollution deadlier than previously thought

70652986 — Mon, 26 Mar 2007 05:04:54 -0400

The idea that air pollution is harmful is hardly new. However, critics of the previous research of Joel Schwartz, associate professor of environmental health at the Harvard School of Public Health, and other air pollution researchers have claimed that those who die from air pollution are the very ill who would have died within a few days in any case. This notion is sometimes referred to as "harvesting." Using a statistical analysis that can factor out expected deaths, Schwartz debunked this argument in a study, "Harvesting and Long Term Exposure Effects in the Relations Between Air Pollution and Mortality" in the March 1, 2000, issue of the American Journal of Epidemiology. If it were true that people who died from air pollution would have died soon anyway, reasoned Schwartz, then there should be a correspondence between an increase in death rates during or immediately following a period of air pollution and a decrease in death rates a few days later. But it doesn't work that way. "Unfortunately, it doesn't work like that," said Schwartz.