Agricultural Burning Smoke Exposure and Health Effect Study in Pullman

• See links to PowerPoint Slides at bottom of page

Wheat growers in eastern Washington and northern Idaho burn wheat stubble that remains in the fields after the wheat harvest. Burning reduces the amount of pesticides that must be applied to control insects, nematodes, and weeds. However, smoke from agricultural burning could contain various air pollutants, including particulate matter (PM), nitrogen dioxide (NO2), CO, and a series of semi-volatile and volatile organic compounds. Inhalation of these air pollutants could result in respiratory symptoms, especially in people with pre-existing respiratory diseases such as asthma or emphysema.

In Oct 1999, Save Our Summers filed a lawsuit claiming that WA Department of Ecology was violating the federal Americans with Disabilities Act by issuing wheat-burning permits to farmers. A settlement agreement was reached in November 2001, pending review of the current agricultural burning rules and results from a health effect study. Currently, the State of Idaho is being sued for their agricultural burning practice.

Researchers of the Northwest Center for Particulate Air Pollution and Health at both the University of Washington (UW) and Washington State Univesity (WSU) initiated an eight-week study in fall 2002 to determine exposure of agricultural burning smoke and related health effects in adults with mild to severe asthma.

Dr. Candis Claiborn, WSU Department of Civil and Environmental Engineering, and Drs. Sally Liu and Joel Kaufman, UW Department of Environmental and Occupational Health Sciences, are co-investigators of this study. According to Dr. Claiborn, "We want to know more about people’s exposure to agricultural field burning smoke. We also want to know if exposure to this smoke affects asthmatic adults. We hope the study results will help us better understand smoke exposure risks and reduce future health risks."

The research team screened volunteers with asthma between 18 and 65 years of age and currently not smoking to participate in the study. The study involved two 30-day periods; one where participants were actively involved by coming to Dr. Claiborn’s lab for lung function tests three times a week, and one where participants were on-call and came to the lab only during burn episodes that effected the Pullman air shed.

Because burn episodes could occur outside predicted periods, on-call participants wore pagers so they could be contacted during a burn episode to come to the lab for lung function meansurements. Participants also measured their lung function four times daily using a device called a spirometer they were given for the term of the study period.

A novel approach in this study is the collection of urine samples for testing of agricultural burning smoke biomarkers. Participants gave two urine samples per day during a burn episode. By examining the quantity of biomarkers present in the urine, researchers can estimate how much agricultural burning smoke participants inhaled during the day. The amount of inhaled smoke will be linked to their lung function measures.

The researchers, however, must separate the effects of smoked food from those of field burning smoke in the biomarkers. They also need to know how a home is ventilated, heated or air conditioned, because all these factors effect the amount of outdoor air pollutants that get indoors. To do so, several outdoor monitors were placed around Pullman, indoor air monitors were placed inside each participant’s home, and the participants were asked to keep detailed ventilation and dietary diaries.

Two volunteers a week wore light-weight personal monitors for particulate matter (PM) measurements for five days. The monitors were worn 24 hours a day. One of the PM monitors is a small light-scattering device that captures the amount of particles in the air breathed anytime during the day. The other PM monitor collects particles on a filter during each 24-hour period. Study technicians placed a light-scattering device in residences on the first day of the study, and visited once a week to check the device, calibrate personal PM monitors, and download data.

Participants in this study learned more about how air pollution affects their homes and how their lungs function. If you would like more information please email at marquist@u.washington.edu, and put "Ag Burn Study" in the subject field.

PowerPoint slides can be viewed:

• Presentation of preliminary results and study design public meeting in Pullman on September 3, 2003
• Presentation of data analysis results public meetings in Pullman and Spokane, WA on June 7, 2004
• Media stories of June 7 meeting