Which areas must be assessed?

Every area of the workplace where there are workers and the NS A is 80 dB(A) or more, including its frequency components (point 5.2).

What must the study record contain?

A description of normal operating conditions and the number of exposed workers by area and job, the method criteria, a plan with the measuring points, the record sheets, the calculations, the calibration documents and the name and signature of the person responsible for the study (Appendix B, point B.7).

Is hiring a laboratory mandatory?

No. Hiring an accredited and approved verification unit or testing laboratory is optional (point 10.1). If one is hired, its results report is valid for two years unless the machinery, equipment, layout or operating conditions change (point 10.5).

How long must the studies be kept?

The hearing conservation programme records, which include the studies, are kept with the information recorded over the last 5 years (points 8.8.1 and 8.8.3(a)).

MX · Expiry & renewal tracking

Never let the noise survey go out of date

Where the noise exposure level (NER) is 80 dB(A) or more, Mexican employers repeat the noise survey and assessment every two years, or within 90 days of a change in production, processes, equipment or controls (NOM-011-STPS-2001, point 8.2.2). Records are kept for five years (point 8.8.1).

NOM-011-STPS-2001, Safety and hygiene conditions in workplaces where noise is generated (DOF 17/04/2002), applies throughout Mexico in every workplace where workers are exposed to noise (point 2). The employer must have a survey and assessment of every area of the workplace where there are workers and the sound level (NS A) is 80 dB(A) or more, including its frequency components, following Appendices B and C (point 5.2).

The survey means identifying the areas and noise sources with a sound level meter, identifying workers with potential exposure, and choosing the assessment method and instruments (point 8.2.1). The assessment uses the methods in Appendix B to determine the noise exposure level (NER) and records the results in the hearing conservation programme documentation (point 8.2.2(a) to (c)).

Where exposure reaches or exceeds an NER of 80 dB(A), the survey and NER assessment are repeated every two years or within ninety days of a change in production, processes, equipment, controls or anything else that could change the results of the previous study (point 8.2.2(d)). The octave-band sound pressure level (NPA) assessment, used to select hearing protection, follows the same rule (point 8.3.1.2(c) and Appendix C).

The assessment record includes, among other things, a description of operating conditions and the number of exposed workers, a plan showing the measuring points, the calculations, and the name and signature of the person responsible for the study (Appendix B, point B.7). Medical exams for exposed workers are a separate obligation with their own frequency.

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At a glance

Who it applies to	Workplaces where workers are exposed to noise (NOM-011-STPS-2001, point 2)
Areas to assess	All areas with workers and an NS A of 80 dB(A) or more (point 5.2)
Repeat study	Every two years, where the NER is 80 dB(A) or more (point 8.2.2(d))
Earlier repeat	Within 90 days of a change in production, processes, equipment or controls (point 8.2.2(d))
Octave bands (NPA)	Same rule: every two years or within 90 days of a change (point 8.3.1.2(c))
Sound level meter calibration	Periodic check by an accredited laboratory, and field calibration at the start and end of each measuring day (Appendix B, B.3)
Testing laboratory report (optional)	Valid for two years unless machinery, equipment, layout or operation change (point 10.5)
Record keeping	Hearing conservation programme records with the information for the last 5 years (point 8.8.1)

Survey and assessment studies are part of the mandatory hearing conservation programme records (point 8.8.3(a)). If control measures are applied, their effectiveness is checked with an assessment within 30 days of applying them (point 8.7.2).

Who is responsible?

The employer must have the survey and assessment (point 5.2) and show the labour authority the records the standard requires (point 5.1). Workers must cooperate with the assessment procedures (point 6.1). The employer may, optionally, hire an accredited and approved testing laboratory, which may carry out the survey and assessment under points 8.2 and 8.3 (points 10.1 and 10.2).

If the deadline passes

Enforcement of NOM-011-STPS-2001 is the responsibility of the Ministry of Labour and Social Welfare (STPS) (point 11). Employers must comply with the official standards on occupational safety and health (Federal Labour Law, Article 132, section XVII), and there are sanctions for employers who do not observe safety and hygiene standards (Federal Labour Law, Articles 992 and 994, section V).

Two years, or 90 days after a change

The two-year interval applies only where the NER is 80 dB(A) or more (point 8.2.2(d)). If you change a machine, a process, production or controls, the study is repeated within the following 90 days even if two years have not passed: in that case, bring the record's expiry forward to the date of the change plus 90 days.

Tracking it with ExpirySuite

Add a record for each workplace or assessed area and enter the date of the last survey and assessment plus two years as the expiry date.
Email reminders arrive 60, 30, 14, 7 and 1 day before the expiry date and on the day, giving time to book the study and measure under normal operating conditions.
The testing laboratory can upload its results report through a secure link that is valid for 14 days and needs no account.
Assign a responsible person, such as the safety team; if the date passes without a study, managers get further reminders 3, 7 and 14 days later.

Frequently asked questions

How often is the noise survey repeated?: Where exposure reaches or exceeds an NER of 80 dB(A), every two years or within ninety days of a change in production, processes, equipment, controls or anything else that could change the results (NOM-011-STPS-2001, point 8.2.2(d)).
Which areas must be assessed?: Every area of the workplace where there are workers and the NS A is 80 dB(A) or more, including its frequency components (point 5.2).
What must the study record contain?: A description of normal operating conditions and the number of exposed workers by area and job, the method criteria, a plan with the measuring points, the record sheets, the calculations, the calibration documents and the name and signature of the person responsible for the study (Appendix B, point B.7).
Is hiring a laboratory mandatory?: No. Hiring an accredited and approved verification unit or testing laboratory is optional (point 10.1). If one is hired, its results report is valid for two years unless the machinery, equipment, layout or operating conditions change (point 10.5).
How long must the studies be kept?: The hearing conservation programme records, which include the studies, are kept with the information recorded over the last 5 years (points 8.8.1 and 8.8.3(a)).

Sources

Last checked: Oct 11, 2026 · This page summarises official sources for general information and is not legal advice. Check the linked sources for current rules and fees.

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