All air bag systems use a pyrotechnic combustion process for the generation of gases. In some systems, it is also used for the heating of stored gases to quickly inflate the air bag. As a by-product of the process, gases and particles are produced that enter the passenger compartment resulting in inhalation of these substances. We have previously shown that systems using sodium azide as the gas generant can initiate asthmatic attacks in susceptible individuals. To evaluate whether the effluents from new-generation, non-azide air bag systems also have the potential to produce adverse responses, we performed controlled exposures of mild to moderate asthmatics to the effluents from six of these air bag systems. Each volunteer asthmatic subject was pulmonary function tested (baseline), and then seated in the back seat of the test vehicle. The air bag system was deployed and the subjects remained in the vehicle for twenty minutes. Pulmonary function testing was again performed immediately after the exposure, and two hours after the exposure. Average particulate levels in the passenger compartment ranged from 12.2-133.3 mg/m3. Ranges for the measured gases were: CO = 63-416 ppm, NO = 8.7-68.7 ppm, and NO2 = 0.3-6.5 ppm. Four of the six new systems tested produced effluents that initiated clinically significant asthmatic reactions in several of the asthmatic subjects. In contrast to the sodium azide systems, the particulate levels attained in the passenger compartment were not a predictor of whether asthmatic reactions would occur.