Exposure Monitoring and Control
Exposure Limits
Currently, there are no OSHA permissible exposure limits (PELs) for 1-bromopropane. The American Conference of
Governmental Industrial Hygienists (ACGIH) has recently revised their recommendation that exposure levels be maintained
at a threshold limit value (TLV) of 0.1 parts per million as an 8-hour time-weighted average (TWA). The U.S.
Environmental Protection Agency (EPA) has previously recommended an exposure level of 25 ppm.
When monitoring employee exposure to 1-bromopropane, the exposure determination must be made without regard to
the use of personal protective equipment, such as respiratory protection. This means that employers cannot apply the level
of protection that the respirator can provide to determine whether an employee is overexposed to 1-bromopropane vapors
present in the workplace environment.
Exposure Assessments and Monitoring
Employers who have a workplace or work operations where 1-bromopropane is used should determine the 8-hour
TWA exposure for each employee exposed, or potentially exposed, to this chemical. In so doing, employers should assess
all work operations for their potential to generate vapors and mists and the effectiveness of existing engineering and
administrative controls. This is done using periodic, or scheduled, monitoring.
Scheduled (Periodic) Monitoring
Initial Monitoring
Scheduled monitoring is the type of exposure monitoring that has been a traditional requirement in OSHA’s substancespecific
standards. Using this type of exposure monitoring, employers perform initial monitoring to determine the 8-hour
TWA exposure for each employee using a sufficient number of samples collected in the employee breathing zone that
fully characterizes their full shift exposure to 1-bromoproane. This should be done for each job classification on every
shift where employees may be exposed.
Does this mean employers must monitor every employee?
No. Employers are only required to conduct monitoring of selected employees that is representative of other employees
in the same job classification working in the same area as the employees monitored.
Periodic Monitoring
The results of initial monitoring are used to establish a recommended frequency of exposure monitoring. If initial monitoring
shows that employee exposure is below an action level (or one-half of the TLV), then monitoring may be discontinued
for the employees that this monitoring represents. If initial monitoring reveals that the represented employees are
exposed at or above the action level (or one-half of the TLV) but not above the TLV, monitoring should be repeated every
six months. If initial monitoring shows employee exposure is above the TLV, monitoring should be repeated every three
months. The recommended schedule for exposure monitoring is summarized in Table 2 below