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ACGIH TLV / Action Limit — Heat Stress Work/Rest Limits

Industrial hygiene screening approach for heat stress and strain using published TLVs for acclimatized workers and published Action Limits for unacclimatized workers.

Open ACGIH TLV / Action Limit in the interactive Guidance Wiki →

Authority

ACGIH

Jurisdiction

Global

Legal status

Technical Standard

Rule type

Schedule Engine

Standard ID

HGC-002

Governing formula

No standalone formula is published for this standard; see programmable logic and parameters below.

Work/rest limits

Acclimatized workers

WBGT (°C)	Light 180 W	Moderate 300 W	Heavy 415 W	Very heavy 520 W
24	60 / 0 min work/rest per hr	60 / 0 min work/rest per hr	50 / 10 min work/rest per hr	45 / 15 min work/rest per hr
25	60 / 0 min work/rest per hr	60 / 0 min work/rest per hr	50 / 10 min work/rest per hr	45 / 15 min work/rest per hr
26	60 / 0 min work/rest per hr	60 / 0 min work/rest per hr	50 / 10 min work/rest per hr	45 / 15 min work/rest per hr
27	60 / 0 min work/rest per hr	60 / 0 min work/rest per hr	50 / 10 min work/rest per hr	45 / 15 min work/rest per hr
28	60 / 0 min work/rest per hr	50 / 10 min work/rest per hr	45 / 15 min work/rest per hr	30 / 30 min work/rest per hr
29	60 / 0 min work/rest per hr	45 / 15 min work/rest per hr	30 / 30 min work/rest per hr	30 / 30 min work/rest per hr
30	60 / 0 min work/rest per hr	30 / 30 min work/rest per hr	30 / 30 min work/rest per hr	15 / 45 min work/rest per hr
31	45 / 15 min work/rest per hr	30 / 30 min work/rest per hr	15 / 45 min work/rest per hr	15 / 45 min work/rest per hr
32	30 / 30 min work/rest per hr	15 / 45 min work/rest per hr	15 / 45 min work/rest per hr	Stop work
33	15 / 45 min work/rest per hr	15 / 45 min work/rest per hr	Stop work	Stop work
34	15 / 45 min work/rest per hr	Stop work	Stop work	Stop work
35	Stop work	Stop work	Stop work	Stop work
36	Stop work	Stop work	Stop work	Stop work

Unacclimatized workers

WBGT (°C)	Light 180 W	Moderate 300 W	Heavy 415 W	Very heavy 520 W
24	60 / 0 min work/rest per hr	60 / 0 min work/rest per hr	45 / 15 min work/rest per hr	45 / 15 min work/rest per hr
25	60 / 0 min work/rest per hr	50 / 10 min work/rest per hr	45 / 15 min work/rest per hr	30 / 30 min work/rest per hr
26	60 / 0 min work/rest per hr	45 / 15 min work/rest per hr	30 / 30 min work/rest per hr	30 / 30 min work/rest per hr
27	60 / 0 min work/rest per hr	30 / 30 min work/rest per hr	30 / 30 min work/rest per hr	15 / 45 min work/rest per hr
28	50 / 10 min work/rest per hr	30 / 30 min work/rest per hr	15 / 45 min work/rest per hr	15 / 45 min work/rest per hr
29	45 / 15 min work/rest per hr	15 / 45 min work/rest per hr	15 / 45 min work/rest per hr	Stop work
30	15 / 45 min work/rest per hr	15 / 45 min work/rest per hr	Stop work	Stop work
31	15 / 45 min work/rest per hr	Stop work	Stop work	Stop work
32	Stop work	Stop work	Stop work	Stop work
33	Stop work	Stop work	Stop work	Stop work
34	Stop work	Stop work	Stop work	Stop work
35	Stop work	Stop work	Stop work	Stop work
36	Stop work	Stop work	Stop work	Stop work

Inputs

Required inputs: wbgtC, workload, acclimatization

Optional inputs: ppe, cafC

Sources

• ACGIH heat stress resources — ACGIH (official public page)
• 🇺🇸 OSHA heat hazard recognition — US OSHA (official)

Related standards

• La Isla Network-informed RSH-s Default Protocol
• TB MED 507 Heat Categories
• NIOSH 2016-106 Table 6-2
• AAFA Guide to Protecting Workers from Heat Stress 2026
• India WBGT Work/Rest Bands (source needs verification)
• Vietnam QCVN 26:2016/BYT
• Hong Kong Labour Department
• Brunei SHENA Heat Stress Guidance
• Malaysia DOSH Heat Stress Guidelines 2016
• El Salvador Decreto No. 89 (TGBH)
• Taiwan High-Temperature Work/Rest Standard
• China GBZ 2.2-2007 Heat Stress Limits
• and 18 more with the same rule type