The efficiency of protective hoods used by sandblasters to reduce silica dust exposure

Several types of respiratory protective hoods used by sandblasters were investigated in two steel fabrication yards. MSA Gravimetric Dust Samplers were used to collect respirable dust samples outside and inside hoods during sandblasting. Colorimetric and x-ray diffraction techniques were applied to the samples for free-silica determination. The majority of the sandblasters, who wore various types of air-supplied hoods, were exposed to an average level of silica dust several times higher than the TLV. Sandblasters wearing non-air-supplied hoods were at the greatest risk. Modern well maintained and properly worn air-supplied hoods offered fair protection during sandblasting periods, but the concentration of suspended respirable dust in ambient air during non-blasting intervals exceeded the TLV by several times.