NR-15 was originally issued by Ordinance MTb No. 3.214 on June 8, 1978, titled “Unhealthy Activities and Operations,” to regulate Articles 189 to 196 of the Consolidation of Labor Laws (CLT), as revised by Law No. 6.514 on December 22, 1977, which amended Chapter V on Safety and Occupational Medicine.
NR-15 defines activities considered unhealthy, entitling workers to additional compensation. It comprises a general part and 13 annexes outlining tolerance limits for physical, chemical, and biological agents, either quantifying contamination or listing conditions for unhealthy work environments.
The thresholds in NR-15 are based on the 1976 American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values (TLV), adjusted for the then-official 48-hour Brazilian workweek. As a definition standard, no National Tripartite Thematic Commission was formed for NR-15.
NR-15 covers worker exposure to noise, heat, ionizing and non-ionizing radiation, hyperbaric conditions, vibration, cold, humidity, chemicals (including benzene), mineral dust (including silica, asbestos, manganese), and biological agents. Quantitative evaluations are required for continuous noise, heat, ionizing radiation, vibration, chemicals, and mineral dust.
Discussions about NR-15 started in 2010, leading to the formation of a Technical Group (GT) for revising the general text. In 2012, a draft was published for public consultation. The GT’s work paused in favor of revising NR-15 annexes, with heat exposure becoming a priority in 2013.
By 2019, the tripartite group concluded the review of the heat exposure annex. The final text was approved in 93% of items, aligning with the updated 2017 Fundacentro Occupational Hygiene Standard (NHO 06).
The updated NR-15 text was published by Portaria SEPRT No. 1.359 on December 9, 2019, with immediate effect. This revision harmonized exposure limits with NHO 06 and updated technical criteria for classifying work as unhealthy due to heat exposure.
NR-15 Unhealthy Activities and Operations
(MTP Ordinance No. 806, of April 13, 2022)
Annex 1 Tolerance Limits for Continuous or Intermittent Noise
Annex 2 – Tolerance Limits for Impact Noise
(SEPRT Ordinance No. 1359, December 9, 2019)
Annex 3 – Tolerance Limits for Heat Exposure
(SEPRT Ordinance No. 1359, December 9, 2019)
Annex 4 (Revoked by MTPS Ordinance No. 3751, November 23, 1990)
Annex 5 of NR15 – Ionizing Radiation
(MTb Ordinance No. 1084, December 18, 2018)
Annex 6 – Works Under Hyperbaric Conditions
(SSMT Ordinance No. 24, September 14, 1983)
Annex 7 – Non-ionizing Radiation
Annex 8 – Vibration
(Amended by MTP Ordinance No. 426, of October 7, 2021)
Annex 11 – Tolerance Limits for Chemical Agents and Inspections in the Workplace
Annex 12 – Tolerance Limits for Mineral Dusts
(SSST Ordinance No. 01, of May 28, 1991)
Annex 13A – Benzene
(MTP Ordinance No. 806, of April 13 of 2022)
Annex 14 – Biological Agents
(SSST Ordinance No. 12, of November 12, 1979)