OSHA’s new silica dust rule sets a very strict standard for workers’ exposure to silica dust. The new permissible exposure level (PEL) is lower than the previous one. For general industry and maritime, the PEL has been cut in half. For the construction industry, which accounts for the vast majority of workers exposed to silica dust, the PEL is 5x lower than it was before. That means companies have a lot of work to do to protect their workers -- and ensure they don’t get hit with big penalties. (In case you didn’t know, OSHA fines went up 78% this year and will be inflation-adjusted going forward.) This article discusses the role of housekeeping and vacuum filtration in keeping the level of respirable crystalline silica below the PEL.
Housekeeping and filtration for general industry and maritime
Read the full standard. The general industry and maritime standard requires employers to implement engineering and work practice controls and to have a written exposure control plan to control exposure to silica dust. The exposure control plan must include:- A description of the tasks that put workers at risk,
- A description of the engineering controls, work practices, and respiratory protection used to limit exposure for each task, and
- A description of the housekeeping measures used to limit exposure.
Vacuuming and dust collection for construction
Read the full standard. In response to the construction industry’s concern that measurement would be difficult and expensive, especially for smaller companies, OSHA provided an alternative way for organizations to comply. Rather than sampling and analyzing the air, as required in the general industry and maritime standard, construction companies can follow the exposure control methods laid out in Table 1. This table essentially acts as a “safe harbor” -- if employers follow it, they will be considered compliant. Table 1 specifies engineering and work practice control methods for common construction tasks. Many of these control methods focus on vacuuming and dust collection.Vacuum filtration requirements - For cleanup
OSHA requires HEPA-filtered (defined as 99.97% efficient @ 0.3-microns) vacuuming for cleanup in several situations:- When cleaning holes from handheld and stand-mounted drills (including impact and rotary hammer drills)
- When cleaning holes from dowel drilling rigs for concrete
- To remove loose dust between passes when using walk-behind milling machines and floor grinders indoors or in an enclosed area
Vacuum filtration requirements - For dust collectors
For dust collectors, OSHA requires filters with a capture efficiency of 99% or greater for “respirable particulate.” This means in some cases, for example, 0.5-micron particulates, 99% is sufficient, while for others (e.g., 3-micron particulates) a greater efficiency (99.97%) is required. This requirement applies to the following situations:- When using handheld power saws (blade diameter < 8 inches) to cut fiber-cement board outside
- When cleaning holes from handheld and stand-mounted drills (including impact and rotary hammer drills)
- When using jackhammers and handheld powered chipping tools, as well as walk-behind milling machines and floor grinders -- in these cases, the dust collector must also have a filter-cleaning mechanism
- When using handheld grinders for mortar removal and other uses -- in these cases, the dust collector must also provide airflow of > 25 cubic feet/minute (CFM) and have a cyclonic pre-separator or filter-cleaning mechanism
