OSHA says the construction provisions would require companies to limit workers' access to areas in which silica levels may be higher than the PEL. It also would require employers to use dust controls to protect workers from such exposure levels and provide them with respirators in areas in which dust controls cannot limit exposure.

Michaels says that, in drafting the proposal, OSHA paid particular attention to its impact on small construction firms and built in flexibility regarding how they can comply with its provisions. He estimates that for construction companies with 20 or fewer employees, the new requirements' annual cost would be $550.

In one example of flexibility, OSHA says in a fact sheet, "Employers can choose to measure their workers' exposure to silica and independently decide which dust controls work best in their workplaces."

The agency adds that companies also would have the option to use a dust-control method listed in the proposed rule for specific construction activities. If a company chooses that option, it would not be required to measure workers' silica exposure.

Michaels says those control devices—listed in a table in the proposal—include "attaching a water hose to a masonry saw [and] putting in a ventilation system." He adds, "All of these are available at Home Depot for small employers and the work that they do."

Michaels also says a company "has to take into account the number of hours a worker is doing a job." Thus, he adds, a worker doing a particular task "all day, every day, may need a respirator," while another worker doing a task for less than a day would not.

The proposal also has training and record-keeping requirements.

In the initial hours after the proposal was unveiled, construction industry officials were just beginning to dig into the voluminous details, which span more than 700 double-spaced pages.

Brian Turmail, an Associated General Contractors of America spokesman, says his group's officials and member firms will be evaluating the proposal, including the reasoning and science behind the major cut in the exposure limit. He adds that AGC hopes the rule "will be effective in addressing something that we all want to accomplish—which is cutting exposures to silica and the chance that our workers could get cancer from it.”

Turmail adds, “We all have the same goal. We just want to make sure that we found an effective way to get there."