The Environmental Protection Agency (EPA) serves as consultants on environmental studies, particularly with regard to human health effects associated with atmospheric exposures. The EPA's Health Effects Research Laboratory (HERL) is equipped with two large human exposure chambers. Experience gained in research using these chambers is invaluable in consulting on environmental and toxic hazards which may have been present in the Persian Gulf region. HERL also has been conducting a study designed to characterize subjects possibly suffering from chemical sensitivities in terms of physiological, immunological, and psychological measures. Results from this study also may contribute to a better understanding of toxic effects from airborne chemical exposures.