PUBLIC LIBRARY / CALCULATOR

Noise dose (Brazilian NR-15, Annex 1)

Adds effects of workday exposure periods at different noise levels and compares with the NR-15 tolerance limit.

Calculate with transparency

Check the population, units and version. The result shows the formula or classification; it does not make an automatic treatment decision.

Preparing the form…

Check the method
Enter the data
Check the result

Method · Limits of application

NR-15 Annex 1: permissible-time table, ΣC/T; intermediate level rounded upward

This calculation uses NR-15 Annex 1 for continuous or intermittent noise, excluding impulse noise. Measurements must use A-weighting, slow response and a position near the worker’s ear. Intermediate levels use the time for the immediately higher level; a C/T sum above 1 exceeds the limit. Exposure above 115 dB(A) without adequate protection carries a specific risk condition. The calculation does not certify measurement or replace the NHO 01 method.

Conditions of use

Check the population, units, inclusion and exclusion criteria, and version in the original source. A result alone does not establish a diagnosis, discharge decision or prescription.

Documented parameters

Period 1: noise level · dB(A)
Period 1: exposure duration · h
Period 2: noise level · dB(A)
Period 2: exposure duration · h
Period 3: noise level · dB(A)
Period 3: exposure duration · h
Period 4: noise level · dB(A)
Period 4: exposure duration · h

7/7 reference cases checked. Numerical tests are not clinical validation.

Sources and documentation

Documented formula

Transcribed from the source or a recorded revision; this is not a clinical recommendation.

Dose = C₁/T₁ + C₂/T₂ + … + C_n/T_n; C is total time at one level and T is maximum permissible daily time at that level (Annex 1 table). If the sum exceeds 1 (100%), exposure exceeds the tolerance limit.

Intermediate levels use the next higher table level’s time (item 4). Decimal hours: 30 min = 0.5 h; 15 min = 0.25 h.

References

Identifier: dose-de-ruido

Original clinical content: Brazilian Portuguese.

Method version

NR-15 Annex 1: permissible-time table, ΣC/T; intermediate level rounded upward

dose-de-ruido@native-2026-10-05+82a10e986bc1

Brasil. Ministério do Trabalho e Emprego. Norma Regulamentadora nº 15 (NR-15): Atividades e Operações Insalubres, com o Anexo 3 alterado pela Portaria SEPRT nº 1.359/2019.

The bibliographic edition identifies the source. By itself, it proves neither full conformity of the formula nor clinical approval.

Synthetic cases checked (7)

Synthetic cases for checking the implementation, with no patient data.

Case 1

reference-001

Inputs

Period 1: noise level: 90 dB(A)
Period 1: exposure duration: 4 h

{
  "n1": 90,
  "t1": 4
}

Expected result

{
  "dose": 1
}

Actual result

{
  "dose": 1
}

Case 2

reference-002

Inputs

Period 1: noise level: 90 dB(A)
Period 1: exposure duration: 4 h
Period 2: noise level: 95 dB(A)
Period 2: exposure duration: 2 h

{
  "n1": 90,
  "t1": 4,
  "n2": 95,
  "t2": 2
}

Expected result

{
  "dose": 2
}

Actual result

{
  "dose": 2
}

Case 3

reference-003

Inputs

Period 1: noise level: 93 dB(A)
Period 1: exposure duration: 1 h
Period 2: noise level: 85 dB(A)
Period 2: exposure duration: 4 h

{
  "n1": 93,
  "t1": 1,
  "n2": 85,
  "t2": 4
}

Expected result

{
  "dose": 0.875
}

Actual result

{
  "dose": 0.875
}

Case 4

reference-004

Inputs

Period 1: noise level: 86.5 dB(A)
Period 1: exposure duration: 3 h

{
  "n1": 86.5,
  "t1": 3
}

Expected result

{
  "dose": 0.5
}

Actual result

{
  "dose": 0.5
}

Case 5

reference-005

Inputs

Period 1: noise level: 97 dB(A)
Period 1: exposure duration: 1.25 h

{
  "n1": 97,
  "t1": 1.25
}

Expected result

{
  "dose": 1
}

Actual result

{
  "dose": 1
}

Case 6

reference-006

Inputs

Period 1: noise level: 88 dB(A)
Period 1: exposure duration: 2 h
Period 2: noise level: 80 dB(A)
Period 2: exposure duration: 6 h

{
  "n1": 88,
  "t1": 2,
  "n2": 80,
  "t2": 6
}

Expected result

{
  "dose": 0.4
}

Actual result

{
  "dose": 0.4
}

Case 7

reference-007

Inputs

Period 1: noise level: 118 dB(A)
Period 1: exposure duration: 0.17 h

{
  "n1": 118,
  "t1": 0.17
}

Expected result

{
  "level": "high",
  "verdict": "grave e iminente"
}

Actual result

{
  "dose": 0
}

Code and reproducibility

This tool’s code on GitHub

Download code and tests

Sources, version and reproduction instructions

README

Local installation

Code license: Apache-2.0

Guidelines and conditions

This repository’s license applies to the code. Third-party instruments, questionnaires, data and models remain subject to their owners’ conditions.

The code tests are technical checks. Clinical approval and professional translation review are recorded separately.

Relationship with cancer research

General context — relationship to be defined

A resource for general clinical contexts. This edition does not assign a specific oncological relationship; selecting it for a study requires a justified question, population and purpose.