for quantitating airborne-allergen concentrations in personal breathing zones.

Assessment of exposure is a rapidly advancing, complex, and multistep process that entails numerous variables and estimations. Most monitoring, for example, is often based on sampling for indicators rather than the actual allergen. There is a need for developing improved methods for estimating environmental concentrations of aeroallergens and the resultant individual exposures.

Research Agenda Item: Develop appropriate exposure metrics for specific indoor allergens that are analogous to time-weighted averages and permissible-exposure limits for industrial chemicals.

ENGINEERING CONTROL STRATEGIES

Dry vacuum cleaning is traditionally used to remove dirt and debris from the fibrous pile of carpets. Little information is available, however, on the effectiveness of this cleaning method in removing the various types of particles, including specific allergens that may adhere to pile fibers, carpet backing, and other furnishings. In addition, the physical cleaning process itself may be sufficient to disperse fine allergenic particles.

Research Agenda Item: Develop standardized tests for rating the effectiveness of vacuum cleaners in removing allergen-containing particles of known size from carpets, upholstery, drapes, and other materials. The tests should take into account the possible dispersion of particles from carpet caused by the cleaning process itself.

The effectiveness of air cleaning devices and practices depends on variables such as the volume of air that passes through the filter, the particle size of the air contaminant to be removed, and the source emission rate. If the air flow rate through an air cleaning device is low, for example, and the emission rate of the allergen is high, then the beneficial effect of the air cleaner is likely to be nonsignificant.

Research Agenda Item: Develop standardized test procedures for rating the effectiveness of air cleaning devices and other methodologies for removal of known size classes of particles containing allergens. The tests should address the capability of the device or methodology in removing airborne particulates from entire rooms or zones of buildings.

Restricted airflow and dissemination of particulates into occupied spaces are valid reasons for cleaning air supply ducts. Protocols for cleaning air



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