CrVI Study Shows Limits, Promise of Local Exhaust Ventilation
The three authors of the paper published in the Journal of Occupational and Environmental Health conducted the research because there have been few studies on welders' exposures, especially in construction.
Setting out to provide data where little research has been done up to now, a trio of authors have shed some light on the level of hexavalent chromium (CrVI) to which welders are exposed during construction work. Their results, published in the November issue of the Journal of Occupational and Environmental Health (an AIHA/ACGIH publication from the Taylor & Francis Group), indicate local exhaust ventilation (LEV) will be helpful if correctly and consistently used.
More research about LEV effectiveness at reducing CrVI exposures is needed, assert authors John D. Meeker of the Department of Environmental Health Sciences, University of Michigan School of Public Health; Pam Susi of the Center for Construction Research and Training (CPWR); and Michael R. Flynn of University of North Carolina Chapel Hill's Environmental Sciences and Engineering.
Their data sources were OSHA's publicly available compliance data; a publicly available exposure database from The Welding Institute; exposure data from two field studies of construction welders done by CPWR; and controlled welding trials conducted by CPWR specifically to assess a portable LEV unit's effectiveness.
The authors compared the concentrations reported in these data with the current OSHA PEL of 5 ug/m3, the current NIOSH recommended exposure level (REL) of 1 ug/m3, and a proposed NIOSH REL of 0.2 ug/m3. They concluded construction welders commonly exceed OSHA's PEL (25 percent of samples from the construction field surveys exceeded it), and that CrVI concentrations varied significantly depending on the type of welding being done. LEV use is likely to significantly reduce welder's exposures in stainless steel welding, but poor placement of the LEV hood can greatly compromise protection, they concluded. They also recommend that researchers not extrapolate non-construction exposures when estimating exposures among the construction population because the latter are at greater risk.