Doctors have suspected for years that forest fires aggravate heart and lung diseases. A 2001 study of Montana hospital admission records by the Centers for Disease Control and Prevention shows that wood fire smoke poses a "serious public health threat," according to published news reports.

The CDC measured and compared more than 2,000 medical records for patients with heart and lung problems among those who sustained varying degrees of exposure to smoke from forest fires. The results: Increases in hospital admission for respiratory and circulatory problems among residents in counties exposed to high levels of fire smoke.

Specifically, the CDC saw increases in coronary artery disease, congestive heart failure, stroke and chronic obstructive pulmonary disease. These increases occurred most during the peak fire period, when pollutant levels were highest.

Medical experts say the fires themselves won't cause breathing problems, but they might reveal asthma in those previously undiagnosed, as particles and toxic gases irritate mucous membranes and cause inflammation.

Those with allergies should pay particular attention, as some allergies heighten the risk of developing asthma. "In people with allergies [the fires] could tip that over into asthma," cautions Dr. Michael Schatz, an allergist with Kaiser Permanente.

This week, the International Association of Fire Fighters worked with Senator Barbara Boxer to pass in the U.S. Senate an amendment that will require NIOSH to conduct long-term health monitoring for firefighters responding to events — such as the wildfires — that have been declared natural disasters by the Federal government.