Many procedures generate hazardous air contaminants that can get into the air that people breath.
Normally, the body can take in limited amounts of hazardous air contaminants, metabolize them and eliminate them from the body without producing harmful effects. When the average air concentrations repeatedly exceed certain thresholds, called exposure limits, adverse health effects are more likely to occur. A very small percentage of individuals experience some discomfort or adverse health effects at or below the exposure limit because of a wide variation in individual sensitivities or pre-existing conditions. Exposure limits for hazardous air contaminants are listed on the material safety data sheets for each product in use. Many organizations research occupational exposures and establish recommended exposure limits.