What the Mexican standard requires
The official catalogue lists NOM-011-STPS-2001 as current. It governs safety and hygiene conditions in workplaces generating noise. Beyond exposure limits, it requires recognition, assessment, information, controls and health surveillance. The occupational noise entry explains the effects; this entry sets out the preventive structure required in Mexico.
The standard uses different acoustic quantities and thresholds for different duties. An instantaneous reading, a person’s exposure level and a trigger for particular measures should not be confused. Directly importing another country’s table can lead to incorrect conclusions about compliance or necessary action.
Recognise and assess exposure
Recognition identifies sources, areas and exposed people and supports selection of methods and instruments. Assessment must reflect actual tasks and durations. A worker moving between areas is not necessarily represented by a single measurement beside one machine.
The text requires recognition and assessment of occupied areas with an A-weighted sound level of at least 80 dB(A). The hearing conservation programme applies to areas with people exposed to levels of 85 dB(A) or above. These trigger different duties; they do not establish that harm is impossible below them.
A programme beyond hearing protectors
The programme integrates measurement, hearing protection selection, training, health surveillance, controls and documentation. Attenuation must be evaluated using the standard’s methods and conditions of use. A figure printed on a protector’s package does not, by itself, establish the protection received by an individual wearer.
Engineering measures can include maintenance, process changes, isolation or acoustic treatment. Organisational measures may limit exposure but require justification and verification. Controls must not introduce new hazards or obstruct essential communications without addressing the consequences.
Evidence and review
Programme documentation retains information from the previous five years. Production changes that could alter exposure require review within the regulatory timescales. Health surveillance should communicate results to each worker and remain under appropriate clinical judgement.
Audiometry does not replace noise reduction. Follow-up should show which sources were corrected and whether exposure decreased, rather than only counting medical examinations. The result is a continuing control process whose records correspond to current working conditions and the people exposed.
