Excursion Limit

The excursion limit is OSHA's short-term ceiling for asbestos: no worker may be exposed to more than 1.0 fiber per cubic centimeter of air averaged over any 30-minute period. It applies alongside the 8-hour average limit of 0.1 f/cc and is meant to catch brief, intense exposures that an all-day average can hide.

Origin

OSHA's 1986 asbestos standards lowered the 8-hour limit but did not include a short-term limit, and after a court challenge OSHA added the 1.0 f/cc, 30-minute excursion limit in the late 1980s. It appears in both the general industry standard (29 CFR 1910.1001) and the construction standard (29 CFR 1926.1101).

Significance in Asbestos Context

Many asbestos jobs involve short, dusty tasks: cutting a gasket, sawing a panel, sweeping up debris, blowing out a brake drum. Those minutes can produce far more fibers than the rest of the shift combined. The excursion limit recognizes this, and short-term sampling is how employers check it. In a claim, the existence of an excursion limit, and short-term readings above it, can help show that a task was hazardous even if the shift average looked acceptable. For exposures before the late 1980s there was no federal short-term asbestos limit, so experts look at task-based sampling, studies and simulations to estimate peaks. Being under a limit does not mean an exposure was safe; the limit reflects what regulators judged feasible to require, not a level proven harmless.

Example Sentence

The 30-minute sample taken while the mechanic cleaned the brake assembly with compressed air was well over the 1.0 f/cc excursion limit.

Related Terms

Time-Weighted Average (TWA), Permissible Exposure Limit (PEL), OSHA Asbestos Standard, Short-Term Exposure, Personal Breathing Zone Sample, OSHA

Notes

• Brief, very dusty tasks matter. Tell your lawyer about them even if they took only minutes, and how often you did them.
• If your employer did air monitoring after the late 1980s, ask whether short-term (30-minute) samples were taken.