On this page

Brazil NR-15 Annex 3 (IBUTG) — Heat Stress Screening Thresholds

Brazil NR-09 Annex III (Calor) and NR-15 Annex 3 occupational heat exposure limits using IBUTG, Brazil’s WBGT-equivalent index.

Browse all standards → · Evaluate every standard at once in the calculator →

Governing metric: IBUTG / WBGT-equivalent
Authority: Brazil Ministry of Labour and Employment
Jurisdiction: Brazil
Legal status: Regulation
In force since: 1978-07-06 (unverified)
Rule type: Screening Limit
Standard ID: HGC-022

Check a reading against this rule

The drag-to-check calculator needs JavaScript. Every value it can show is a row of the table below, which is computed by the same engine.

Governing formula

Outdoor IBUTG = 0.7 Tbn + 0.1 Ta + 0.2 Tg

Screening thresholds

Acclimatized workers

WBGT (°C)	Light 180 W	Moderate 300 W	Heavy 415 W	Very heavy 520 W
24	Within the NR-09 Annex III Quadro 2 (acclimatised) limit (30.8°C max IBUTG at 180W).	Within the NR-09 Annex III Quadro 2 (acclimatised) limit (28.2°C max IBUTG at 300W).	See notes below the table	See notes below the table
25	Within the NR-09 Annex III Quadro 2 (acclimatised) limit (30.8°C max IBUTG at 180W).	See notes below the table	See notes below the table	See notes below the table
26	Within the NR-09 Annex III Quadro 2 (acclimatised) limit (30.8°C max IBUTG at 180W).	See notes below the table	See notes below the table	See notes below the table
27	Within the NR-09 Annex III Quadro 2 (acclimatised) limit (30.8°C max IBUTG at 180W).	See notes below the table	See notes below the table	See notes below the table
28	Within the NR-09 Annex III Quadro 2 (acclimatised) limit (30.8°C max IBUTG at 180W).	See notes below the table	See notes below the table	See notes below the table
29	See notes below the table	See notes below the table	See notes below the table	See notes below the table
30	See notes below the table	See notes below the table	See notes below the table	See notes below the table
31	See notes below the table	See notes below the table	See notes below the table	See notes below the table
32	See notes below the table	See notes below the table	See notes below the table	See notes below the table
33	See notes below the table	See notes below the table	See notes below the table	See notes below the table
34	See notes below the table	See notes below the table	See notes below the table	See notes below the table
35	See notes below the table	See notes below the table	See notes below the table	See notes below the table
36	See notes below the table	See notes below the table	See notes below the table	See notes below the table

Unacclimatized workers

WBGT (°C)	Light 180 W	Moderate 300 W	Heavy 415 W	Very heavy 520 W
24	Within the NR-09 Annex III Quadro 1 (non-acclimatised or unstated) limit (28.1°C max IBUTG at 180W).	Within the NR-09 Annex III Quadro 1 (non-acclimatised or unstated) limit (25°C max IBUTG at 300W).	Average IBUTG (24°C) exceeds the NR-09 Quadro 1 exposure limit for non-acclimatised workers (23°C at 415 W).	Average IBUTG (24°C) exceeds the NR-09 Quadro 1 exposure limit for non-acclimatised workers (21.6°C at 520 W).
25	Within the NR-09 Annex III Quadro 1 (non-acclimatised or unstated) limit (28.1°C max IBUTG at 180W).	Average IBUTG (25°C) exceeds the NR-09 Quadro 1 exposure limit for non-acclimatised workers (25°C at 300 W).	Average IBUTG (25°C) exceeds the NR-09 Quadro 1 exposure limit for non-acclimatised workers (23°C at 415 W).	Average IBUTG (25°C) exceeds the NR-09 Quadro 1 exposure limit for non-acclimatised workers (21.6°C at 520 W).
26	Within the NR-09 Annex III Quadro 1 (non-acclimatised or unstated) limit (28.1°C max IBUTG at 180W).	Average IBUTG (26°C) exceeds the NR-09 Quadro 1 exposure limit for non-acclimatised workers (25°C at 300 W).	Average IBUTG (26°C) exceeds the NR-09 Quadro 1 exposure limit for non-acclimatised workers (23°C at 415 W).	See notes below the table
27	Within the NR-09 Annex III Quadro 1 (non-acclimatised or unstated) limit (28.1°C max IBUTG at 180W).	Average IBUTG (27°C) exceeds the NR-09 Quadro 1 exposure limit for non-acclimatised workers (25°C at 300 W).	See notes below the table	See notes below the table
28	Within the NR-09 Annex III Quadro 1 (non-acclimatised or unstated) limit (28.1°C max IBUTG at 180W).	Average IBUTG (28°C) exceeds the NR-09 Quadro 1 exposure limit for non-acclimatised workers (25°C at 300 W).	See notes below the table	See notes below the table
29	Average IBUTG (29°C) exceeds the NR-09 Quadro 1 exposure limit for non-acclimatised workers (28.1°C at 180 W).	See notes below the table	See notes below the table	See notes below the table
30	Average IBUTG (30°C) exceeds the NR-09 Quadro 1 exposure limit for non-acclimatised workers (28.1°C at 180 W).	See notes below the table	See notes below the table	See notes below the table
31	See notes below the table	See notes below the table	See notes below the table	See notes below the table
32	See notes below the table	See notes below the table	See notes below the table	See notes below the table
33	See notes below the table	See notes below the table	See notes below the table	See notes below the table
34	See notes below the table	See notes below the table	See notes below the table	See notes below the table
35	See notes below the table	See notes below the table	See notes below the table	See notes below the table
36	See notes below the table	See notes below the table	See notes below the table	See notes below the table

Inputs

Required inputs: wbgtC, metabolicRateW

Optional inputs: acclimatization

Sources

🇧🇷 Brazil NR-09 (atualizada 2026) Anexo III Calor, incl. Portaria MTE 105/2026 — Brazil Ministério do Trabalho e Emprego (official)
🇧🇷 Brazil NR-15 Annex 3 heat exposure limits — Brazil Ministério do Trabalho e Emprego (official)
🇧🇷 Brazil Portaria SEPRT 1.359/2019 heat update — Brazil Ministério do Trabalho e Emprego (official)

Update history

2026-10-14 · Guidance changed
This standard’s output changed in the reference scenarios, in a form that does not reduce to permitted work minutes (for example a screening limit, risk level, or respirator tier).
2026-10-14 · Guidance changed
This standard’s output changed in the reference scenarios, in a form that does not reduce to permitted work minutes (for example a screening limit, risk level, or respirator tier). Registry fields changed — optionalInputs: added acclimatization.
2026-07-26 · Scope or legal status changed
Recovered from repository history: ruleType changed. The direction of the safety effect was not computed, because reproducing it would require running the engine as it stood on that date.
2026-05-11 · Added to the calculator
This standard was added to the calculator.