Researchers at Georgia Tech Research Institute (GTRI) in Atlanta have developed a portable sensor system to monitor the air quality for people suffering from asthma. The device is a combination of sensors that measure the level of chemicals in the air thought to cause asthma attacks, such as ozone, volatile organic compounds, and formaldehyde. It is lightweight and small enough to fit into a patient's pocket, so exposure levels can be continuously monitored.

The only way that we are going to understand how environmental factors affect asthma is if we can measure a person's exposures on a day-to-day basis, says Charlene Bayer, the leader of the Environmental Exposures and Analysis Group at GTRI and the sensor system's principal investigator. "To do so, we need a device like this that can hold numerous sensors in a small, portable package.".

An estimated 20 million Americans suffer from asthma, according to the National Institutes of Health (NIH), and identifying the triggers of an attack is currently a guessing game. "There are a few devices on the market that measure one or two chemicals, but they are stationary and the size of a desktop computer," says Mark Jones, the chief executive officer of Keehi Technologies and the lead engineer developing the sensor system.

Currently, the only way to control an asthma attack is with medication, or "trigger avoidance." In 2007, the total health-care costs of asthma in the United States were approximately $19.7 billion, according to the NIH.

"Research has shown that if you can reduce the triggering of an asthma attack, you will reduce the impact of the disease," says Mark Millard, the director of the Baylor Martha Foster Lung Care Center at Baylor University Medical Center in Dallas, TX. The new sensor system, he says, is really trying to answer the question, "What are the triggers for people with asthma?"

The device is about the size of a cell phone and contains a total of five sensors that measure different possible asthma triggers: ozone, nitrogen dioxide, formaldehyde, carbon dioxide, and total volatile organic compounds--the brew of chemicals that are emitted as gases from products such as paints, cleaning supplies, and building materials. The device also includes temperature and humidity sensors and a clock, to put a time stamp on the measurements. The researchers used sensors already on the market and kept the device small by outfitting the sensors on a two-sided circuit board.

Establishing a timeline is important for late-phase reactions, says Millard, since reactions to compounds such as formaldehyde may happen four to six hours after a patient is exposed. "Now we can look at the data and know that a patient was exposed to a lot of those compounds and that could be the trigger."