Ceiling Limit

What Does Ceiling Limit Mean?

The ceiling limit is the maximum concentration of a toxic substance to which a person can be exposed to.

Unlike some other standardized limits, ceiling limits do not have an exposure time. It represents a concentration that is immediately hazardous and should be avoided for any amount of time.

Safeopedia Explains Ceiling Limit

The Occupational Safety and Health Administration (OSHA) sets permissible exposure limits (PEL) for various hazards. Workers should not be exposed to hazards in levels that exceed these PELs.

There are three types of limit:

• Time-weighted average: an exposure level that can be tolerated for a given period of time (typically eight hours, representing the average work shift)
• Short-term exposure limit: an exposure level that should only be permitted during a very brief span of time (typically 15 minutes)
• Ceiling limit: an exposure that should not be exceeded for any amount of time

Some substances will have all three types of limit specified. This means that adhering to the time-weighted average is sufficient for lower concentrations/intensities of the hazard, but in higher concentrations exposure should be avoided entirely.

While OSHA and Cal/OSHA set regulatory permissible exposure limits, the National Institute of Safety and Health (NIOSH) and the American College of Governmental Industriual Hygienists (ACGIH) also specify a set of recommended exposure limits.