Table 1 Maximum Use Concentrations
Respirator Type
Respirator Use
Respirators with
Particulate Filters or
Filter Cartridges
Routine Use in Supplied-Air Mode - Including Entry
Continuous Use and Non-Emergency Egress
1,000 Times Exposure
Limit
Routine Use in Air-Purifying Mode - Including Entry,
Continuous Use, Non-Emergency Egress and /or Moving
from Station-to-Station
50 Times Exposure Limit
Emergency Escape in Air-Purifying Mode
Unlimited
Exposure Limits for Mixtures
The American Conference of Government Industrial Hygienists (ACGIH) publishes the following information to determine the
TLV of a mixture.
First, determine the total concentration of the chemical mixture (CMixture) from the individual contaminant concentrations (C
1
,
C
2
, C
3
...) using the following formula:
C
Mixture
= C
1
+C
2
+C
3
+...
The TLV of the mixture is found by using the following formula where T
1
, T
2
, T
3
... are the individual contaminant TLVs and C
1
,
C
2
, C
3
, ... are the individual contaminant concentrations:
Only use these equations if the contaminants present are actually mixed. Some substances do not mix and may be present
separately, for example, in pockets or at different levels. In that case, the lowest TLV of the substances present must be used
to determine the appropriate respirator category for protection against all contaminants present.
Exposure Limits
A listing of acceptable exposure limits from the following sources.
• American Conference of Government Industrial Hygienists (ACGIH)
• Occupational Safety and Health Administration (OSHA)
• National Institute for Occupational Safety and Health (NIOSH)
• American Industrial Hygiene Association (AIHA)
Contact MSA at 1-800-MSA-2222 for information.
US
Abrasi-Blast Respirator
8
1 Introduction
