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

Brazil NR-15 Annex 3 occupational heat exposure limits using IBUTG, Brazil’s WBGT-equivalent index.

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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

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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

WBGT (°C)	Light 180 W	Moderate 300 W	Heavy 415 W	Very heavy 520 W
24	Within the NR-15 Annex 3 Table 1 limit (30.8°C max IBUTG at 180W).	Within the NR-15 Annex 3 Table 1 limit (28.2°C max IBUTG at 300W).	Within the NR-15 Annex 3 Table 1 limit (26.6°C max IBUTG at 415W).	Within the NR-15 Annex 3 Table 1 limit (25.5°C max IBUTG at 520W).
25	Within the NR-15 Annex 3 Table 1 limit (30.8°C max IBUTG at 180W).	Within the NR-15 Annex 3 Table 1 limit (28.2°C max IBUTG at 300W).	Within the NR-15 Annex 3 Table 1 limit (26.6°C max IBUTG at 415W).	Within the NR-15 Annex 3 Table 1 limit (25.5°C max IBUTG at 520W).
26	Within the NR-15 Annex 3 Table 1 limit (30.8°C max IBUTG at 180W).	Within the NR-15 Annex 3 Table 1 limit (28.2°C max IBUTG at 300W).	Within the NR-15 Annex 3 Table 1 limit (26.6°C max IBUTG at 415W).	See notes below the table
27	Within the NR-15 Annex 3 Table 1 limit (30.8°C max IBUTG at 180W).	Within the NR-15 Annex 3 Table 1 limit (28.2°C max IBUTG at 300W).	See notes below the table	See notes below the table
28	Within the NR-15 Annex 3 Table 1 limit (30.8°C max IBUTG at 180W).	Within the NR-15 Annex 3 Table 1 limit (28.2°C max IBUTG at 300W).	See notes below the table	See notes below the table
29	Within the NR-15 Annex 3 Table 1 limit (30.8°C max IBUTG at 180W).	See notes below the table	See notes below the table	See notes below the table
30	Within the NR-15 Annex 3 Table 1 limit (30.8°C max IBUTG at 180W).	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

This standard's declared inputs do not include acclimatization status, so results do not vary by it.

Inputs

Required inputs: wbgtC, metabolicRateW

Optional inputs: none

Sources

🇧🇷 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

2026-07-26 · 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.