Component analysis of respirator user training.

Respirators must be properly used to be effective. In an experimental protocol, 145 subjects were trained and then observed donning and doffing respirators. Filtering facepiece and dual cartridge half face mask types were studied. Subjects were then tested for knowledge and for proper performance using video recording analysis. Knowledge tests showed adequate learning, but performance was often poor. Inspection, strap tension (half mask), seal checking, and avoiding mask contact during doffing were particularly problematic. Mask positioning was generally well done. Correlation between knowledge and performance for specific items was generally poor, although there was a weak correlation between overall knowledge and overall performance (rho = 0.32) for the half mask users. Actual unprompted performance as well as knowledge and fit-testing should be assessed for user certification. Respirator design approval should consider users' ability to learn proper technique.

Heads or tails: do stranded fish (mosquitofish, Gambusia affinis) know where they are on a slope and how to return to the water?

Aquatic vertebrates that emerge onto land to spawn, feed, or evade aquatic predators must return to the water to avoid dehydration or asphyxiation. How do such aquatic organisms determine their location on land? Do particular behaviors facilitate a safe return to the aquatic realm? In this study, we asked: will fully-aquatic mosquitofish (Gambusia affinis) stranded on a slope modulate locomotor behavior according to body position to facilitate movement back into the water? To address this question, mosquitofish (n = 53) were placed in four positions relative to an artificial slope (30° inclination) and their responses to stranding were recorded, categorized, and quantified. We found that mosquitofish may remain immobile for up to three minutes after being stranded and then initiate either a "roll" or a "leap". During a roll, mass is destabilized to trigger a downslope tumble; during a leap, the fish jumps up, above the substrate. When mosquitofish are oriented with the long axis of the body at 90° to the slope, they almost always (97%) initiate a roll. A roll is an energetically inexpensive way to move back into the water from a cross-slope body orientation because potential energy is converted back into kinetic energy. When placed with their heads toward the apex of the slope, most mosquitofish (>50%) produce a tail-flip jump to leap into ballistic flight. Because a tail-flip generates a caudually-oriented flight trajectory, this locomotor movement will effectively propel a fish downhill when the head is oriented up-slope. However, because the mass of the body is elevated against gravity, leaps require more mechanical work than rolls. We suggest that mosquitofish use the otolith-vestibular system to sense body position and generate a behavior that is "matched" to their orientation on a slope, thereby increasing the probability of a safe return to the water, relative to the energy expended.

Comparison of three respirator user training methods.

OBJECTIVE: This study addresses methods for training respirator users, particularly when occupational health professionals are not immediately available. METHODS: A randomized trial compared three training methods-printed brochure, video, and computer-based training-for two respirator types (filtering facepiece and a dual-cartridge half facemask). Quantitative fit testing (PortaCount) measured the effectiveness of training. The study included 226 subjects. RESULTS: For both respirator types, video was significantly superior to either print or computer-based training methods. Conclusions were consistent, whether determined by average fit factor (analysis of variance), log-transformed fit factors, or the number of users in the lowest quartile of achieved fit. CONCLUSIONS: Video training for proper respirator use can be effective when direct training from an occupational health professional is unavailable. These methods are particularly relevant to "rapid rollout" situations, such as natural disasters, epidemics, or bioterrorism concerns.