The Stage 1 alert for southwest Idaho has been cancelled, and the red air quality alert for the Treasure Valley has been lowered to yellow Saturday.

But bad air with the poor quality seen in area throughout the week is connected to health problems in Treasure Valley, according to a recent Boise State study.

Smoke impacts from wildfires are expected to improve this weekend, but the BSU study suggests there is still reason for concern.

The study shows a strong link between a marked decline in air quality in the Treasure Valley and increased visits to doctors' offices, emergency departments and hospitals.

"As air quality worsens even when we are in acceptable levels we still are seeing health effects from it," said Dr. Lee Hannah, a Boise State Epidemiologist.

The study involved 27 months of data covering more than a million health care visits for nine different health issues ranging from asthma to heart attacks, said Hannah.

The pollutant examined was particulate matter including wood burning and auto exhaust.

Researchers collected data from Blue Cross of Idaho, Regence Blue Shield and Medicaid for patients under the age of 65 who visited a doctor between Oct. 1, 2002, and Dec. 31, 2004. That data was cross-referenced with air quality monitor data from the Department of Environmental Quality.

Results show a definite increase in upper and lower respiratory disease risk when air quality declines, as well as an increased risk in heart disease within three days after a rise in particulate matter.

"We are going to continue to have bad air in the Treasure Valley during the winter. With the inversion in summer with the ozone levels and so, even when the smoke clears and things calm down this still needs to be something that is important to us," said Dr. Hannah.

The study was unique in that it involved data from outpatient visits as well as hospital visits. It also excluded Medicare patients, meaning the study represents fairly healthy adults instead of a vulnerable sector of society.