Noise at Work: How to Calculate and Control Exposure (UK & OSHA Guide)

Noise-induced hearing loss is permanent. Unlike many workplace injuries, you cannot recover from it — the damage accumulates silently over years and is often not noticed until it is severe. It is also almost entirely preventable. Understanding your legal obligations and the practical steps to protect workers is both a legal requirement and a straightforward exercise once you know the numbers.

Why Noise Matters

Approximately 17,000 people in the UK suffer deafness, tinnitus, or other ear conditions as a result of excessive noise at work. The HSE estimates the total cost to society at hundreds of millions of pounds per year in lost productivity, healthcare, and compensation claims.

Noise-induced hearing loss (NIHL) is one of the most common occupational diseases in the UK and a regular subject of civil compensation claims. Employers have been found liable for NIHL caused by exposure to noise levels that were known to be hazardous, even where the exposure occurred decades before the claim.

The UK Legal Framework

The Control of Noise at Work Regulations 2005 implement the EU Physical Agents (Noise) Directive and apply to virtually all workplaces except music and entertainment venues, where separate provisions apply.

The Regulations establish three exposure action values and one exposure limit value, all expressed as daily or weekly personal noise exposure (LEP,d or LEP,w) measured in decibels A-weighted (dB(A)).

The exposure limit value of 87 dB(A) accounts for the attenuation provided by hearing protection — meaning the actual noise level at the ear must stay below 87 dB(A) even when protection is being worn.

The 3 dB Rule (UK/International Standard)

The science behind noise measurement is based on logarithms. Because the decibel scale is logarithmic, every 3 dB increase doubles the sound energy reaching the ear, which means exposure time must be halved to maintain the same risk level.

This is the basis of the equal energy rule used in UK and European standards:

• 85 dB(A) for 8 hours = the upper action value baseline
• 88 dB(A) for 4 hours = the same exposure dose
• 91 dB(A) for 2 hours = the same exposure dose
• 94 dB(A) for 1 hour = the same exposure dose

This matters practically because many workers in noisy environments do not work at a constant noise level all day. A worker who spends two hours at 91 dB(A) and six hours at 78 dB(A) may have a total daily exposure that exceeds 85 dB(A) even though most of their day is spent at a relatively quiet level.

OSHA's 5 dB Exchange Rate (US Standard)

For businesses operating in or familiar with US standards, it is worth noting that OSHA uses a 5 dB exchange rate rather than the 3 dB equal energy rule. Under OSHA:

• 90 dB(A) for 8 hours = the permissible exposure limit
• 95 dB(A) for 4 hours = the same exposure level
• 100 dB(A) for 2 hours = the same exposure level

OSHA also requires a hearing conservation programme when noise levels reach an action level of 85 dB(A) averaged over 8 hours.

The practical difference is that the OSHA 5 dB rule is less protective than the UK 3 dB rule at higher noise levels. A worker exposed to high-intensity noise for short periods accumulates a higher dose under the UK standard than under the OSHA standard for the same pattern of exposure.

Measuring Noise Levels

Noise exposure assessment requires measurement using a sound level meter or noise dosimeter. Spot measurements with a sound level meter can give useful indicative readings, but for accurate daily exposure calculations — particularly where workers move between different noise environments — a dosimeter worn by the worker throughout the shift is more reliable.

Measurement should be carried out by, or under the supervision of, a competent person. The results should be recorded and used to identify which workers require action at the lower and upper action values.

The Hierarchy of Noise Controls

As with all workplace hazards, the first priority is to reduce noise at source, not to rely on hearing protection.

Eliminate or substitute. Can the process be changed? Pressing components instead of riveting them, for example, can dramatically reduce impact noise. Can quieter machinery be specified when existing equipment is replaced?

Engineering controls. Isolate or enclose noisy equipment. Use vibration damping on surfaces. Fit silencers to compressed air outlets. Maintain equipment to prevent noise from deteriorating bearings or loose panels.

Administrative controls. Rotate workers through noisy tasks to limit individual exposure. Create quiet rest areas away from noisy processes. Schedule noisy work when fewer people are present.

Hearing protection. When noise cannot be reduced below the upper action value by other means, suitable hearing protection must be provided and its use enforced. The protection selected must provide adequate attenuation for the specific frequency profile and intensity of the noise — an SNR or HML calculation should be carried out to verify this.

Health Surveillance

Where workers are regularly exposed above the upper action value, or where a risk assessment indicates risk at lower levels, employers must provide health surveillance. This typically involves periodic audiometric testing by a qualified audiometrist, with results compared over time to identify any early signs of hearing deterioration.