Under OSHA's silica rules, an employer may not allow compressed air to be used to clean clothing or surfaces where that could contribute to silica exposure. There are two exceptions. The first is that the air is used with a ventilation system that captures the dust cloud. The second is that no other method is feasible.

This question comes up because most sites already own a compressor and a blow gun. The rule decides whether workers can use that tool at cleanup time and at the end of a shift. It also decides what must replace it.

How the restriction works

For construction, the rule is paragraph (f)(2) of 29 CFR 1926.1153, the respirable crystalline silica standard. General industry and maritime employers are covered by the parallel standard, 29 CFR 1910.1053. This article quotes the construction text.

The standard became effective on June 23, 2016. Employers had to comply in full from June 23, 2017.

The employer shall not allow compressed air to be used to clean clothing or surfaces where such activity could contribute to employee exposure to respirable crystalline silica unless: (i) The compressed air is used in conjunction with a ventilation system that effectively captures the dust cloud created by the compressed air; or (ii) No alternative method is feasible.

29 CFR 1926.1153(f)(2)
Respirable Crystalline Silica, Housekeeping, OSHA

The rule is applied in this order:

  1. Trigger. The ban applies only if blowing could contribute to employee exposure to respirable crystalline silica. If the dust contains no silica, or no one could be exposed, the paragraph does not apply.
  2. Exception (i). If a ventilation system effectively captures the dust cloud the air creates, compressed air is allowed.
  3. Exception (ii). If no alternative method is feasible, compressed air is allowed.
  4. Otherwise, the employer must not allow it.

Paragraph (f)(1) applies the same logic to brooms and brushes. Dry sweeping and dry brushing are prohibited where they could contribute to exposure. The exception is when wet sweeping, HEPA-filtered vacuuming or other methods that minimize exposure are not feasible.

The limits behind both rules are set out on OSHA's construction silica page. The permissible exposure limit is 50 micrograms per cubic meter. The action level is 25 micrograms per cubic meter. Both are 8-hour time-weighted averages. Blowing settled dust puts it back into the air.

Alternatives for surfaces and for clothing

CPWR's Silica Safe housekeeping guidance lists the methods it prefers. The principle is to remove settled dust with moisture or filtration, not to disperse it.

Surfaces

  • Water spray applied directly at the dust source.
  • Wet mopping and wet wiping.
  • Sweeping compounds that contain no silica. OSHA recognizes dust-suppression sweeping compounds as acceptable when they are used according to the manufacturer's instructions.
  • HEPA-filtered vacuums. A standard shop vacuum does not meet this.

Clothing

  • HEPA-equipped vacuums provided so workers can clean dust off their clothing before leaving the site.
  • Washing facilities located close to the worksite.

The filter rating a vacuum must carry is covered separately, under what filter rating OSHA requires.

Some plants use enclosed clothes-cleaning booths that blow air at the worker. A booth like this can only rely on exception (i). The sources used here do not set design or performance criteria for these booths. They also do not say how an employer shows that a booth "effectively captures" the dust cloud.

Where it applies on a site

End-of-shift clothing. A worker who has cut or ground concrete is covered in dust. If that worker blows off with a shop air line, the dust is put back into the breathing zone and the ban applies. The CPWR alternative is a HEPA vacuum used on the clothing.

Surface cleanup after a task. Dust settles on slabs, benches and equipment. If blowing or dry sweeping that dust could expose workers, it is prohibited where wet methods, sweeping compounds or HEPA vacuuming are feasible.

Compressed air inside a dust extractor. Some extractors used with source-capture tools release a burst of compressed air to clean the internal HEPA filter without the unit being opened. One example is the Guardair PulseAir line. This is a manufacturer's description of its own product. The air does not clean clothing or an open surface. The (f)(2) ban addresses those two uses only.

What the ban is not

Common reading What the text says
Compressed air is banned on any silica site. The ban covers cleaning clothing or surfaces where it could contribute to exposure. Other uses of compressed air are not addressed by (f)(2).
Compressed air is allowed if workers wear respirators. Respirators are not one of the two exceptions. The exceptions are capturing ventilation and the infeasibility of every alternative.
A broom is the safe substitute. Dry sweeping and dry brushing carry their own ban under (f)(1) where wet sweeping or HEPA vacuuming is feasible.

What an inspector looks for

In construction, the written exposure control plan required by 1926.1153(g) must describe housekeeping methods. Listing compliant methods in place of blowing and dry sweeping is covered under the written exposure control plan.

The quoted text does not require a separate written determination when an employer relies on the "no alternative method is feasible" exception. No OSHA interpretation letter on this paragraph was found for this article. An employer who relies on that exception should expect to be asked why wet methods and HEPA vacuuming could not be used.

The regulation contains no penalty figures. Penalties come from OSHA's separate penalty schedule. In 2026, a serious violation carries up to $16,550 and a willful violation up to $165,514, as reported by EHS Today.