Workplace Chemical Monitoring - Occupational Health and Workplace Monitoring at Chemical Agent Disposal Facilities - page 10

Exposure Limits and Process Control Levels

Systematic quality control procedures are followed
to ensure the reliable operation of ACAMS and
DAAMS monitors. Each ACAMS monitor is routinely
challenged with dilute agent solutions to confirm that
appropriate alarm levels are being maintained.
DAAMS tubes spiked with known agent levels are also
added to field samples undergoing analysis on a ran-
dom schedule to confirm that the monitoring system
can detect and quantify adsorbed agent. Electronic
records of ACAMS monitor alarms and challenges and
the results of analyses of DAAMS tubes are created on
a daily basis and eventually archived (U.S. Army,
1997a).

The alarm levels for deployed ACAMS monitors at
various facility sites are typically set at 20 percent of a
specific airborne exposure limit or process control
level. Thus, the absence of an ACAMS monitor alarm
may be assumed to indicate that no agent concentra-
tions of more than 20 percent of the airborne exposure
limit have persisted for longer than the cycle period
(~3 to 8 minutes). The Army has set exposure limits
and process controls at the levels mandated (in per-
mits) for current disposal facility operations (U.S.
Army, 1997a). These are reprinted in Table 2-2. The

TABLE 2-2 Airborne and Related Exposure Limits and Process Control Levels

Exposure Limit for Each Chemical Agent (mg/m 3 )

HD a

Purpose Applicable Level GB VX

Nonagent worker b 10 -6 10 -6 10 -4 ) c GPL 3 × 3 × (1 ×

and general population level
Unmasked agent worker b,d

TWA e,f 1 × 10 -4 1 × 10 -5 3 × 10 -3

Ceiling value g 1 × 10 -4 1 × 10 -5 3 × 10 -3

Source emission limit, ASC 3 × 10 -4 3 × 10 -4 3 × 10 -2

process control levels GLD NA NA 0.2

ECL h 0.01 NA NA

IDLH 0.2 0.02 NA

MPL 100 NA 100

a The presence of HT is determined by monitoring for the HD component.
b No individual is intentionally exposed to direct skin or eye contact with any amount of neat agent or to solid materials contaminated with
agent.
c This level of detection (using a 12-hour sampling time) should be demonstrated and used at all sites where mustard is transported and
destroyed.
d Devices for sampling and analyzing workplace air measure and alarm within 10 minutes when chemical agents are present in concentrations
of one TWA or higher.
e The TWA is also referred to as the worker population limit (WPL).
f TWA DAAMS monitoring may be performed using a 12-hour method.
g The ceiling value is the maximum concentration an individual may be exposed to at any time for any duration. Practically, it is the average
value over the maximum time required to detect and quantify the specified concentration (U.S. Army, 1990, 1991).
h ECL monitoring levels can vary depending on the monitoring application. The laboratory identifies each ECL monitoring level application
in the site-specific agent monitoring plan.

ASC = allowable stack concentration IDLH = immediately dangerous to life and health (30 min)

ECL = engineering control level MPL = maximum permissible limit (with workers in DPE suits)

GLD = gross level detector NA = not applicable

GPL = general population limit (24-hr day, 7-day week) TWA = time-weighted average (8-hr day, 40-hr week)

Source: Adapted from U.S. Army, 1997a, 1997b.