Page 37 - Occupational Health & Safety, December 2018

The familiar hierarchy of controls shows that elimination is the most effective risk control strategy, while PPE is the least effective.
cluding concealed spaces in walls or floors. ■ Combustible materials are adjacent to the opposite side of metal partitions, walls, ceilings, or roofs and are likely to be
ignited by conduction or radiation.
Fire watchers also “shall be familiar with facilities for sounding an alarm in the event of a fire. They shall watch for fires in all ex- posed areas, try to extinguish them only when obviously within the capacity of the equipment available, or otherwise sound the alarm. A fire watch shall be maintained for at least a half hour after completion of welding or cutting operations to detect and extinguish possible smoldering fires,” ac- cording to the standard’s text.
The standard says welding and cutting are not to be permitted in some specific circumstances: locations where it is not authorized by management; in sprinklered buildings while that protection is impaired; in the presence of an explosive atmosphere, or when explosive atmospheres may de- velop inside uncleaned or improperly prepared tanks or equipment that previ- ously contained such materials or that may develop in areas with an accumulation of combustible dusts; or in areas near the stor- age of large quantities of exposed, readily ignitable materials.
Welding Fume
Arc welding also may produce fumes, which are composed of metals and usu- ally contain a small amount of manganese, according to NIOSH. Studies have shown neurological damage associated with work- ers’ exposure to manganese in welding fumes, the agency has reported.
A study3, funded in part by NIOSH, of the prevalence of manganese exposures among welders in the construction in- dustry was presented at the 2013 AIHce
conference by Michael R. Flynn of the University of North Carolina Chapel Hill and co-author Pam Susi, CIH, MSPH, of CPWR; it is still available on the eLCOSH (Electronic Library of Construction Oc- cupational Safety & Health) website. They analyzed a data set from OSHA of more than 100,000 measurements from approxi- mately 30,000 welders in various industries over 30 years, from 1978 to 2008. The au- thors used the OSHA data to characterize the welders’ eight-hour time-weighted ex- posures to airborne contaminants, focus- ing on manganese and evaluating mixed exposures with additive effects, especially manganese and lead. They reported that both heavy construction and structural steel erection welders had an elevated risk of overexposure to manganese and lead jointly, and there was limited evidence of declines in exposures over time for one substance and group: iron in special trade contractors. The authors recommended a reduced PEL for manganese, increased use of local exhaust ventilation by construction welders, and targeting both joint exposures and carcinogens of concern, notably cad- mium and hexavalent chromium.4
Jerry Laws is the editor of Occupational Health & Safety.
REFERENCES
1. https://www.bls.gov/ooh/production/weld- ers-cutters-solderers-and-brazers.htm
2. https://www.osha.gov/SLTC/etools/ electricalcontractors/prefabrication/welding. html#Static%20and%20Awkward%20Postures
3. http://www.elcosh.org/record/docu- ment/3679/d001220.pdf
4. https://www.cdc.gov/niosh/topics/hex- chrom/default.html
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