Recirculating Industrial Air: The Impact on Air Compliance and Workers' Safety Case Study: Hill Air Force Base C-130 Painting Operations

摘要

Recent Clean Air Act regulations require industries, including aircraft painting facilities, to capture volatile organic compound (VOC) emissions. Because aircraft painting contaminates large airflows with traces of VOCs, conventional air control systems would be prohibitively expensive to apply. Recirculating a portion of the air back into the facility is an option to reduce the amount of air to be treated. A computer model is presented that will calculate air control costs and chemical concentrations at selected recirculation levels. Air concentrations are compared to occupational exposure limits (OELs) to analyze worker safety. The model has a chemical database containing over 1300 chemicals. A case study has been performed on a C-130 aircraft painting facility at Hill Air Force Base, Utah. The model predicts strontium chromate concentrations during application of primer paints will reach 1000 times the OEL, and that the concentration will increase by only 1 or 2% at 90% recirculation. Exposures to strontium chromate and other particulate contaminants are affected only slightly by recirculation because airborne solids are removed efficiently when the air is filtered prior to recirculation. The respiratory protection required for the strontium chromate adequately protects workers from increased concentrations of volatile chemicals, which are caused by recirculation. The model demonstrates that recirculating 75% of the air at the Hill AFB facility has a negligible impact on safety and could save $2.7 million on the initial expenses of a VOC control system.