Global positioning system (GPS) devices are everywhere these days—in cars, cell phones, dog collars—and now, even in asthma inhalers. Researchers from the University of Wisconsin–Madison recently launched a study using GPS devices to monitor where and when patients use their inhalers, a technology they hope will uncover unrecognized triggers of asthma symptoms.

Scientists have long known that environmental factors such as pollen, cigarette smoke, and air pollutants aggravate symptoms of asthma, such as wheezing, coughing, and shortness of breath. But the leader of the study David Van Sickle, an epidemiologist at the UW School of Medicine and Public Health says it's likely there are unknown environmental culprits. Figuring out exactly when and where asthma attacks occur can help pinpoint these aggravators, he adds.

There are some 82,000 chemicals used commercially in the U.S., but only a fraction have been tested to make sure they're safe and just five are regulated by the U.S. Environmental Protection Agency (EPA), according to congressional investigators. But a government scientist says there's no guarantee testing actually rules out health risks anyway.

The basic premise of safety testing for chemicals is that anything can kill you in high enough doses (even too much water too fast can be lethal). The goal is to find safe levels that cause no harm. But new research suggests that some chemicals may be more dangerous than previously believed at low levels when acting in concert with other chemicals.

"Some chemicals may act in an additive fashion," Linda Birnbaum said this week at a conference held at the Columbia Center for Children's Environmental Health at Columbia University. "When we look one compound at a time, we may miss the boat."

Is sunshine more than just a home remedy for a cold? New research suggests it may be: In a study that will be published tomorrow, people with low levels of vitamin D — also known as the "sunshine vitamin" — were more likely to catch cold and flu than folks with adequate amounts. The effect of the vitamin was strongest in people with asthma and other lung diseases who are predisposed to respiratory infections.

People with the worst vitamin D deficiency were 36 percent more likely to suffer respiratory infections than those with sufficient levels, according to the research in this week's Archives of Internal Medicine. Among asthmatics, those who were vitamin D deficient were five times more likely to get sick than their counterparts with healthy levels. And the risk of respiratory infection was twice as high among vitamin D-deficient patients with chronic obstructive pulmonary disease (COPD) than in lung patients with normal levels of the vitamin.

Just how many months of life is clean air worth? Five to be precise, according to a new study published today in the New England Journal of Medicine.

"Who would have thought you could get almost half a year in increased life expectancy on average just from cleaning up our air somewhat?" says study co-author Arden Pope, an environmental economist at Brigham Young University in Provo, Utah. "That seems to me like a pretty good investment" in clean-air programs.

Pope and Harvard University colleagues compared improvements in air quality with increased life expectancy between 1980 and 2000. Their findings, based on air-monitoring and health data from 51 U.S. metro areas: five months of the nearly three additional years of life tacked on during that period stemmed from cleaner air.

Good news and bad news for asthma patients who use inhalers: You won't be expelling Earth-warming chlorofluorocarbons (CFC's) into the atmosphere  with every puff, but you will pay six times as much for your green medical device.

Until now, inhalers have been powered by CFCs, which destroy the ozone layer. On Dec. 31, all albuterol inhalers will be propelled by hydrofluoroalkane (HFA), which is better for the environment, the Associated Press reports. But it will cost you: $30 to $60, compared  with $5 to $10 now.

Albuterol is used on an emergency basis to open the airways of asthma patients suffering from severe wheezing. They take other, daily meds to control their asthma.

Asthma, a respiratory disease whose prevalence skyrocketed in the latter part of the 20th century, is  believed to have a genetic component, and environmental triggers—including pollution and pests— are also blamed.  Now a common infant virus—respiratory syncytial virus (RSV)—is being fingered as a possible cause.

Babies born in autumn, about four months before RSV's peak season, are 30 percent more likely to develop asthma by the time they're five than kids who are older and have stronger immune systems when RSV is in high circulation, according to research in this week's American Journal of Respiratory and Critical Care Medicine.

The number of children with food and digestive allergies has increased by 18 percent over the past decade, a new report shows, underscoring a trend reported by concerned parents and teachers.

The number of kids under 18 with those allergies climbed from 2.3 million in 1997 to 3 million last year, according to a report released today by the Centers for Disease Control (CDC). Some 90 percent are caused by just eight foods: milk, eggs, peanuts, tree nuts, fish, shellfish, soy and wheat.

The findings are based on a national health survey of the parents of 9,500 children who were asked whether their kids had experienced a digestive or food allergy in the previous year. Because the results aren’t based on allergy diagnoses, that makes it unclear whether the rise is real or reflects a greater awareness of the condition, says CDC statistician Amy Brandum, who co-authored the report.

The long-term effects of the 9/11 attacks aren’t merely existential. Whether the collapse of the Twin Towers and exposure to the stew of dust and chemicals caused disease, and the emotional toll it took on witnesses, are scientific questions, too.

New estimates suggest that of the more than 400,000 people who were directly exposed to the strikes, 35,000- to- 70,000 developed post-traumatic stress disorder (PTSD), and 9,700-to-2,000 people experienced serious psychological distress. Some 3,800 to 12,600 people may have developed asthma, New York City epidemiologists report in this month's Journal of Urban Health.