Study: Difficult to control respirable silica levels during chipping, crushing
- It is difficult to protect workers and bystanders from respirable silica during chipping and crushing activities, even when dust control measures are in place, according to a study conducted by researchers at the Department of Public Health at the University of Massachusetts Lowell.
- Researchers took 51 worker and 33 bystander breathing zone air samples at several Massachusetts construction sites where demolition, chipping and crushing activities were in progress. Chipping workers and crushing machine tenders had the highest exposure to respirable silica, with levels above the Occupational Safety and Health Administration’s permissible exposure limit (PEL) within 15 minutes to two hours for chippers — even with cartridge respirators — and crushers, respectively. Bystanders could also be exposed to high levels of respirable silica during demolition.
- Exposure for those individuals who operated crushing machines was lowered below the PEL by using a water spraying system. However, even with such control measures, chipping and crushing activities create a challenge for contractors trying to reduce the level of respirable silica, so researchers suggested that respiratory protection measures might be necessary for these tasks.
There is no indication that OSHA plans to amend the silica rule because of this or any other study that came out subsequent to the agency enacting the revised standard in 2016, when it lowered the PEL and instituted other measures related to respirable silica. That rulemaking process was contentious, as some industry groups pushed back against how much implementing the new standard would cost contractors and argued that tighter restrictions were not necessary.
However, in October, just before the UMass Lowell study was published, OSHA began asking for public input on possible changes to the silica rule and some of what was unearthed in the study could make its way into the standard via that route. Currently, contractors that use the rule's Table 1 control methods do not have to measure worker exposure and do not have to abide by the standard's PEL's. Also up for a potential revision is how effective dust control methods are in reducing worker exposure to silica. The input period closed in December.
Silica violations haven’t made it to the top of OSHA’s Top 10 list, but the agency has certainly hit the ground running when it comes to proposing silica-related fines and issuing citations. In August, the agency cited Lanford Bros. Co. of Marion, Virginia, for inadequate eye and face protection under the relatively new silica standard. OSHA issued the company two serious violations and proposed fines of $304,130. Lanford has contested the violations. Within the first six months of enforcing the rule, OSHA issued 116 citations for silica violations.
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