Public Release: 

National Jewish, EPA put HEPA filters, air purifiers to the test

National Jewish Health

DENVER-HEPA-filter equipped vacuums and air filtration systems are used in many homes on the assumption that the devices lower allergic symptoms by removing allergens and irritants from the floor and air, respectively.

A National Jewish Medical and Research Center study will look at how effective these devices really are in removing various allergens and irritants such as cat dander, endotoxins, dust and tobacco smoke from the homes of children with asthma. Second, third and fourth-graders from the Kunsberg School, National Jewish¡|s on-site school for children with chronic illnesses, are participating in the study.

Funded by the Environmental Protection Agency, this study seeks to learn how or if the use of an electrostatic air filtration system and the daily use of a HEPA-filter equipped vacuum reduce asthma symptoms and attacks, and/or medication use of children with asthma. The high efficiency particulate air filter, known commonly as a HEPA filter, is frequently found attached to vacuums, but there have been few scientific studies to verify the benefits of either system being tested for people with asthma.

"We want to find out if these interventions make a difference in lowering the amount of allergens and irritants in the home, and if the kids get better once we¡|ve done something to the environment," said Nathan Rabinovitch, M.D., a pediatric asthma specialist at National Jewish and principal investigator of the federally-funded study. "If we do see a difference, these types of devices might be one way to help lower asthma severity in some children."

In today's more energy-efficient, less-drafty homes, the exchange between indoor and outdoor air is decreasing, so finding an effective way to clean indoor air and remove dust could help people with asthma and other lung diseases.

"The tighter the homes, the less ventilation," Dr. Rabinovitch said. "The more venting you have the less allergens are a problem."

The two-month study begins with a team from National Jewish and the EPA monitoring classrooms and the children¡|s homes for dust, cigarette smoke and endotoxins, which are dead bacteria known to stimulate inflammation in the lungs. The team also will measure each home¡|s fresh air exchange, and cooling and heating ventilation systems. Following the environmental evaluation of the home, half the homes will receive an air filtration system and a HEPA filter vacuum; the other half will be in the control group. (Parents will be responsible for vacuuming every day of the week.) After the initial assessment, the team will check the classrooms and homes once more. National Jewish researchers will compile and analyze the collected information.

Throughout the study, sophisticated air monitoring stations will be used to record the size, and the types of allergens and irritants found at each home.

All the children in the study will continue to take their regular asthma medications. Medication inhalers will be equipped with a mini-computer that will register when the children use their medications. The children will fill out diaries and for four days will carry personal air samplers, as well.


This project is being conducted in collaboration with Shelly Miller, Ph.D., an assistant professor in the Mechanical Engineering Department at the University of Colorado.

For more information about asthma, indoor and outdoor air pollutants, call LUNG LINE, 800-222-5864 or e-mail,

The Number 1 Respiratory Hospital in the U.S. for Two Consecutive Years, U.S. News & World Report, 1998-2000.

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