The objective of this study was to quantify the respirable dust and respirable silica exposures of roofing workers using an electric powered circular saw with an aftermarket local exhaust ventilation attachment to cut concrete roofing tiles. The study was conducted to determine whether the local exhaust ventilation attachment was able to control respirable dust and respirable silica exposure below occupational exposure limits (OEL). Time-integrated filter samples and direct reading respirable dust concentrations were evaluated. The local exhaust ventilation consisted of a shroud attached to the cutting plane of the saw; the shroud was then connected to a small electric axial fan, which is intended to collect dust at the point of generation. All sampling was conducted with the control in use.

BACKGROUND: Investigations of carbon monoxide (CO) related poisonings and deaths on houseboats were conducted by the Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health. These investigations measured hazardous CO concentrations on and around houseboats that utilize gasoline powered generators. Engineering control devices were developed and tested to mitigate this deadly hazard. METHODS: CO emissions were measured using various sampling techniques which included exhaust emission analyzers, detector tubes, evacuated containers (grab air samples analyzed by a gas chromatograph), and direct reading CO monitors. RESULTS: CO results on houseboats equipped with gasoline powered generators without emission controls indicated hazardous CO concentrations exceeding immediately dangerous to life and health (IDLH) levels in potentially occupied areas of the houseboat. Air sample results on houseboats that were equipped with engineering controls to remove the hazard were highly effective and reduced CO levels by over 98% in potentially occupied areas. CONCLUSION: The engineering control devices used to reduce the hazardous CO emissions from gasoline powered generators on houseboats were extremely effective at reducing CO concentrations to safe levels in potentially occupied areas on the houseboats and are now beginning to be widely used.

Occupational exposure to silica in the construction industry has been well documented,(1–7) and respirable crystalline silica (quartz and cristobalite) has been associated with silicosis,(8,9) lung cancer,(10,11) pulmonary tuberculosis,(12,13) and airway diseases.(14,15) | These concerns prompted a local construction union to request assistance from the National Institute for Occupational Safety and Health (NIOSH) for health hazard evaluations concerning exposures to dust and silica among roofers in Phoenix, Arizona. In response to these requests, NIOSH performed field studies to evaluate roofers’ exposures to silica.