Table of contents  •  Who we are ... people and programs  •  Where we've been ... and where we're going  •  
Facts and figures  •  Acknowledgments


What we do ... and whom we serve  •  Particulate air pollution

Sacred objects,
safely returned

Beyond the laboratory walls

Breathing safely in the dusty trades

Particulate air pollution

Probing genetic variations

We've all heard the warnings on bad-air days- young children, the elderly, and those with respiratory problems are asked to stay indoors. Does that really protect them? Research projects from Assistant Professor Sally Liu's laboratory are challenging that conventional wisdom by investigating how the air quality inside the homes of susceptible people correlates with outdoor air quality and health effects.

Liu is working under two grants frsom the US Environmental Protection Agency (EPA), which has the goal of protecting the public-especially sensitive populations-from exposure to harmful air pollution.

Policy making

When the EPA set its standard for fine particulate matter (PM2.5) in 1997, critics said it was over-protective, not based on sound science, and ques-tioned whether sensitive populations were really exposed to the dirty air, because their health problems forced them to stay inside. The EPA didn't know much about exposures of such people or the exact health effects of fine particulates, Liu said.

	Lab manager Tim Gould sets up a sampler to measure ozone and sulfur dioxide

Her study recruited elderly subjects (average age 75) with heart and lung problems, children with asthma, and healthy elderly controls-107 in all-and studied them over one to three 10-day periods. Her study is the largest of its kind funded by the EPA.

The research subjects wore monitors to measure their personal exposure to fine particulate matter, nitrogen dioxide, sulfur dioxide, organic chemicals, and other components of air pollution. They each kept an activity diary, recording what they were doing every 15 minutes, and a pollution event diary, recording when they cooked, if they burned the toast, whether the windows were open, and whether they vacuumed, burned candles, or built a wood fire. They also recorded how well they felt each day and which medications they took.

The study took place from fall 1999 through spring 2001. The project team included environmental scientists, engineers, pulmonologists, chemists, toxicologists, and biostatisticians from the University of Washington, Washington State University, Lawrence Berkeley National Laboratories, and agencies such as the state Department of Ecology, Puget Sound Clean Air Agency, and EPA. Much of the fieldwork was done by departmental graduate students and about two dozen undergraduates.

Research subjects wear monitors to measure their personal exposure

Researchers took health and employment histories, daily urine and breath samples, pulmonary function tests, pulse readings, blood pressure, blood oxygen-saturation levels, and electrocardiograms. They also measured air quality inside and outside the house, and measured the air exchange rate in the home using a tracer chemical.

The hypothesis was that higher exposures to particulate matter and organic compounds from combustion would be associated with measurable differences in cardiovascular tests and symptoms.

Early findings

Early findings showed a correlation between poor air quality and symptoms. "We saw lower heart rate variability on bad PM (particulate matter) days," Liu said, "but we can't really say exactly what caused the health effects." Professor Dan Luchtel is conducting toxicological tests with a special mouse model that is similar to elderly humans with cardiovascular problems to better understand the trigger mechanisms. Departmental researchers, headed by Professor Dave Kalman, are also doing biomarker studies with the urine samples to better understand how much of the outdoor pollution gets inside homes and into human bodies.

Research Technician Christine Sleeman checks the flow rate of air sampling systems

Air quality measurements showed that indoor air could be as bad as that outdoors. Small particles that were generated outside in the atmosphere found their way indoors. The smallest particles, those that cause the greatest health concern because they are breathed deeper into the lungs, behave almost like gases and closing the windows and doors doesn't keep them out. Nearly half (44%) of the personal exposures came from outdoors. "We see infiltration on bad air days. People are told to stay inside, but that may not be enough to prevent exposure," Liu said.

Health recommendations

About half the elderly subjects lived in single-family homes and half in senior housing. Pollutant expo-sures were generally lower for those who lived in senior housing where meals were served in a central dining room. Continuous readout air quality moni-toring showed dramatic spikes when people cooked or ran vacuum cleaners. This information suggests that senior citizens with severe heart or respiratory illnesses might consider moving to housing that provides meals and housekeeping services, so they could leave the apartment during vacuuming.

While the second-year data are still being analyzed, the first year's findings can be useful to EPA. "Our goal is to give EPA a good indication of what sources to control in a regulation, and what components in the PM the regulatory agency should focus on," Liu said. Already, researchers have identified the most important outdoor particulate and indoor pollution sources and how much they contribute to poor air quality.

Kalman identified another ground-breaking aspect of the study. "For the first time, we are expecting to describe how particularly vulnerable individuals experience their environment, in quantitative and statistical terms. This will enable policy makers to consider not only regulations to protect the general public, but also to understand how additional protection for those at highest risk might be achieved." He suggested that additional efforts may have to be made to control in-home sources of air pollution.

For further reading

Box M. Exposure to particulate matter among older adults with chronic obstructive pulmonary disease: Relation between personal, indoor, and outdoor concentrations. Master's thesis, University of Washington, 2000.
http://depts.washington. edu/envhlth/news/abstract/abstracts_box.html

Goswami E. Spatial characteristics of fine matter and nitrogen dioxide in Seattle: identifying representative monitoring sites. Master's thesis, University of Washington, 2001. http://depts.washington.edu/envhlth/news/abstract01/abstracts_goswami.html

Mar TF, Norris GA, Koenig JQ, Larson TV. Associations between air pollution and mortality in Phoenix, 1995-1997. Environ Health Perspect 2000;108:347-353.

Norris G, YoungPong SN, Koenig JQ, Larson TV, Sheppard L, Stout JW. An association between fine particles and asthma emergency department visits for children in Seattle. Environ Health Perspect 1999;107:489-493.

Norris G, Larson T, Koenig J, Claiborn C, Sheppard L, Finn D. Asthma aggravation, combustion, and stagnant air. Thorax. 2000 Jun;55(6):466-70.

Sheppard L, Kaufman J. Sorting out the role of air pollution on asthma incidence. Epidemiology 2000;11:100-101.

Yu O, Sheppard L, Lumley T, Koenig JQ, Shapiro GG. Effects of ambient air pollution on symptoms of asthma in Seattle-area children enrolled in the CAMP study. Environ Health Perspect 2000;108:1209-1215.