Noise Exposure Assessment
A professional noise exposure assessment evaluates how workplace sound levels, task duration and employee work patterns combine to affect daily and weekly occupational noise exposure. It interprets that exposure against the UK Control of Noise at Work Regulations 2005 to determine where employer action is required.
80 dB(A)
Lower action value
85 dB(A)
Upper action value
87 dB(A)
Exposure limit value
Daily & weekly personal exposure
Interpreted against UK action and limit values
What it is
What is a noise exposure assessment?
Occupational noise exposure is the cumulative effect of the sound an employee is exposed to during their working day. It depends not only on how loud individual sources are, but on how long workers spend in different conditions and how their tasks combine across a shift.
Sound level alone is therefore not sufficient to characterise risk. A relatively quiet but continuous task can contribute more to daily exposure than a louder but brief one, and several different activities — quieter periods, breaks and high-noise tasks — combine into a single daily personal exposure figure. That is what an exposure assessment quantifies.
A credible assessment requires representative work patterns. The measured shift must reflect normal operating conditions, the sampled workers must represent their similar exposure group, and unusual or non-representative events must be documented so the results can be interpreted in context. Exposure assessment is how isolated measurements become evidence the employer can act on. For the broader assessment exercise, see our workplace noise surveys service; for the measurement programme that produces the underlying data, see workplace noise monitoring.
Why it matters
Why exposure assessment matters
Exposure assessment puts measured noise into the context of how people actually work. It is the basis on which sensible decisions about controls, hearing protection and health surveillance can be made.
Noise-induced hearing loss
Identify exposure that may contribute to permanent, preventable hearing damage among workers.
Tinnitus and hearing damage
Highlight tasks and roles where the risk of tinnitus and temporary or permanent threshold shifts is greatest.
Identify groups at risk
Pinpoint similar exposure groups whose work patterns put them at elevated occupational noise risk.
Prioritise controls
Rank tasks and processes by their contribution to exposure so engineering and organisational controls target the right activities first.
Compare with action values
Determine whether the lower or upper exposure action values, or the exposure limit value, are approached or exceeded.
Support risk assessment
Provide the measurement evidence and interpretation that underpins your workplace noise risk assessment.
Inform hearing protection
Use measured exposure and frequency content to guide the selection and use of suitable hearing protection where required.
Evidence for compliance
Document a defensible basis for decisions about controls, hearing protection zones and health surveillance.
Level & duration
Exposure level and duration
Occupational noise exposure depends on both how loud a task is and how long the worker is exposed to it. Louder noise generally allows less safe exposure time before action values are approached, while lower-level noise sustained over many hours can still produce significant daily exposure.
Repeated short tasks can also matter. A handful of brief but high-level activities — short grinding runs, hammer impacts, pneumatic discharges — can contribute disproportionately to a worker's LEX,8h once their frequency and combined duration are taken into account. Conversely, where loud tasks are limited to a small share of the day, daily exposure may sit well below the level that the noise sources themselves might suggest.
Several different tasks usually combine into a single daily exposure result. This is why the assessment must reflect actual work duration, not assumed time on noisy equipment, and why a simplified level-versus-time table cannot substitute for a professional assessment of the specific job being done.
LEX,8h
Daily personal exposure — LEX,8h
LEX,8h is the daily personal noise exposure level — the cumulative A-weighted noise an individual is exposed to during a working day, normalised to a notional eight-hour reference period. Normalisation to eight hours allows different workers, roles and shifts to be compared on a common basis, regardless of actual shift length.
Where a worker performs several tasks, each task's contribution is combined by level and duration. Quieter tasks and rest periods do reduce the overall energy total, but they do not undo the contribution of loud activities — a small share of a shift spent on a high-noise task can still drive LEX,8h above an action value.
Because LEX,8h depends on representative durations, it cannot be determined from a single instantaneous decibel reading. Realistic task and shift data are required for the calculation to mean anything.
Weekly exposure
Weekly personal exposure
Weekly personal noise exposure (LEX,40h) may be relevant where daily exposure varies markedly from day to day. Examples include roles where loud tasks are concentrated on certain days, shifts that rotate through different work areas, or maintenance crews whose noise exposure depends on the equipment being worked on.
Weekly averaging is subject to regulatory conditions and is not a general route to disregard high daily exposures. Where individual days are unusually loud, where peak sound pressure action values are exceeded, or where adequate controls are not in place, those issues still require attention regardless of the weekly average.
Whether weekly averaging is appropriate is a judgement made during scoping, based on the pattern of work and the controls available. The assessment report sets out which basis has been used and why.
Action & limit values
Exposure action values and exposure limit value
The UK Control of Noise at Work Regulations 2005 set the occupational noise framework against which exposure is interpreted. The figures below are the thresholds that drive employer duties.
Lower exposure action value
80 dB(A) LEX,8h
135 dB(C) peak
Trigger for information, instruction and training, hearing protection availability and exposure assessment.
Upper exposure action value
85 dB(A) LEX,8h
137 dB(C) peak
Trigger for a noise control programme, mandatory hearing protection zones and health surveillance.
Exposure limit value
87 dB(A) LEX,8h
140 dB(C) peak
Must not be exceeded — takes account of any reduction provided by hearing protection actually worn.
Employer responsibilities scale with exposure: from information and training at the lower action value, through mandatory hearing protection and a documented control programme at the upper action value, to the absolute requirement not to exceed the limit value at the ear. For the broader regulatory context, see our Noise at Work Regulations guidance, or read Understanding Noise Action Values for a closer look at the 80, 85 and 87 dB(A) thresholds, or Noise-Induced Hearing Loss Explained for the underlying health effects.
Methodology
How exposure is assessed
Each exposure assessment is scoped to the workplace. The workflow below is typical; not every step applies to every project, and not every assessment requires personal dosimetry.
- 1
Review work activities and shifts
Understand production patterns, shift structures and the tasks that drive employee noise exposure.
- 2
Identify similar exposure groups
Group employees with comparable tasks, locations and patterns so a representative sample reflects each group.
- 3
Review existing risk assessments
Build on any prior noise data, risk assessments and control records before planning new measurements.
- 4
Task and area measurements
Calibrated sound level meter measurements of representative tasks, work positions and machinery.
- 5
Personal noise dosimetry where appropriate
Shift-length dosimetry for representative workers within each exposure group, where mobile or variable work warrants it.
- 6
Record task durations
Document how long workers spend on each activity so each task's contribution to LEX,8h can be calculated.
- 7
Review non-representative events
Identify and document unusual events, breakdowns or atypical shifts so they are not mistaken for normal exposure.
- 8
Exposure calculations
Combine measured levels and durations into daily (and, where appropriate, weekly) personal exposure following ISO 9612 methodology.
- 9
Peak-noise consideration
Assess LCpeak alongside LEX,8h wherever impact, impulsive or pneumatic sources are present.
- 10
Interpret against action values
Compare measured exposure against the lower, upper and limit values defined in the Control of Noise at Work Regulations 2005.
- 11
Control and hearing protection recommendations
Set out prioritised, practical actions covering elimination, engineering control, organisational measures and hearing protection.
- 12
Technical reporting
Issue a clear written report including methodology, results, interpretation and recommended next steps.
Similar exposure groups
Similar exposure groups
A similar exposure group (SEG) is a set of workers whose tasks, locations and work patterns are comparable enough that their noise exposure can reasonably be characterised together. Rather than measuring every employee individually, exposure is assessed for representative members of each SEG.
Representative workers are selected so that the measured shift fairly reflects typical work within the group — not the quietest or busiest day, and not an atypical role. Variation between workers, shifts and tasks must still be considered: if SEG members differ materially in their actual exposure, the grouping is revisited and, where needed, additional monitoring is carried out.
The grouping decisions, the workers sampled and the reasoning behind them are documented so the assessment is transparent and can be reviewed against future changes in work patterns.
Measurement methods
Personal dosimetry and task measurements
Different methods answer different questions. The appropriate combination depends on the work being assessed.
Personal noise dosimeters
Body-worn dosimeters that follow representative workers through their shift, capturing mobile and variable exposure.
Integrating sound level meters
Class 1 or Class 2 SLMs used for task and area LAeq measurements at representative work positions.
Task-based measurements
Short, focused measurements of discrete operations so each task's contribution to daily exposure can be quantified.
Area measurements
Fixed-position readings characterising noise around machines, lines and shared workspaces.
Observation & activity logs
Documented task durations, breaks and unusual events that put measurement data into context.
Representative sampling
Sampling planned around similar exposure groups rather than every individual employee.
Dosimeter results should not be interpreted without an understanding of the worker's actual activities. See our dedicated personal noise dosimetry service for more on this method.
Peak & impulsive noise
Peak and impulsive noise
Sudden, impulsive noise events — impact noise, hammering, pressing, metal-on-metal impacts, pneumatic tools, cartridge tools and loading impacts — present a hearing risk that average A-weighted exposure measures do not fully capture. The Control of Noise at Work Regulations 2005 therefore set separate peak sound pressure (LCpeak) action and limit values alongside the daily exposure thresholds.
Where impulsive sources are present, peak measurements are taken and reported alongside LEX,8h, and peak risk is considered in its own right. Treating average exposure as the only consideration can underestimate the hearing risk from short, very loud events — which is why peak noise is assessed separately.
LCpeak action values: 135 dB(C) (lower), 137 dB(C) (upper), 140 dB(C) (limit).
Quality control
Factors that can invalidate exposure results
Exposure data is only useful if it represents normal work. A competent assessment plans, observes and documents the measurement period so the following risks can be identified and managed.
- Abnormal production conditions during the measurement period
- Unusually quiet or unusually busy shifts that are not representative
- Incorrect wearing or positioning of a personal noise dosimeter
- Microphone obstruction by clothing, PPE or hand-held tools
- Workers altering their normal behaviour because they are being monitored
- Incomplete or inaccurate task-duration records
- Equipment interference, wind noise or other measurement artefacts
- Unrecorded breaks, meetings or temporary off-task activities
- Sampling periods that do not reflect normal operations
- Single-shift sampling where exposure varies materially day to day
Observation alongside measurement, documented task durations and pre/post calibration checks materially reduce the risk that non-representative conditions are mistaken for typical exposure.
Deliverables
What the client receives
- Assessment scope, methodology and shift coverage
- Identified similar exposure groups with rationale
- Task and shift information for each representative worker
- Measurement results — task, area and personal dosimetry as applicable
- Daily personal exposure (LEX,8h) findings
- Weekly personal exposure findings where relevant
- Peak sound pressure (LCpeak) findings
- Comparison of exposure against the action and limit values
- Identification of higher-risk activities and contributing tasks
- Prioritised, practical control recommendations
- Hearing protection observations and selection considerations
- Technical report suitable for internal compliance records
- Recommended next steps and review timing
The assessment provides competent measurement, interpretation and recommendations to support employer duties under the Control of Noise at Work Regulations 2005. It does not constitute legal certification or a guarantee of compliance.
From findings to controls
Exposure assessment and noise control
A well-scoped assessment ranks tasks and processes by their contribution to exposure so controls can be applied where they will have the greatest effect. Hearing protection sits within a wider hierarchy of measures — not as the default first option.
Elimination
Remove the noise source where reasonably practicable — for example by retiring obsolete noisy equipment.
Substitution
Replace noisier machinery, tools or processes with quieter alternatives.
Engineering controls
Damping, silencers, acoustic enclosures, vibration isolation and quieter component design.
Isolation & enclosure
Separate workers from noise sources using acoustic barriers, enclosed control rooms or distance.
Maintenance
Address wear, imbalance and worn bearings that frequently increase noise output over time.
Organisational controls
Adjust work patterns, job rotation and scheduling to limit individual exposure duration.
Reduced exposure duration
Reorganise tasks so loud activities occupy a smaller share of any one worker's shift.
Hearing protection
Where exposure cannot be controlled sufficiently by other means, appropriately selected and used PPE.
Health surveillance
Where required, audiometric surveillance to monitor for early signs of noise-related hearing change.
Coverage
Industries and activities assessed
Workplace noise exposure assessments across UK industrial and commercial workplaces. Common environments include:
Manufacturing
Production lines
Engineering
Fabrication
Woodworking
Logistics
Warehouses
Construction
Recycling
Plant rooms
Maintenance
Mobile & mixed-task roles
Why us
Why choose Workplace Noise Surveys
Occupational hygiene-led assessment
Assessments designed around employee exposure and risk control, not just isolated dB readings.
Representative measurement strategies
Sampling planned around similar exposure groups and normal operating conditions.
Practical industrial understanding
Experience working efficiently within live production, workshops, warehouses and construction sites.
Calibrated, traceable equipment
Class 1/2 integrating sound level meters and personal noise dosimeters with pre- and post-measurement calibration.
Clear exposure interpretation
Findings interpreted against the UK regulatory framework with practical, prioritised next steps.
UK regulatory context
Reports written for the Control of Noise at Work Regulations 2005 framework and HSE guidance L108.
Actionable recommendations
Control and hearing-protection recommendations that distinguish quick wins from longer-term engineering work.
Green Air Monitoring network
Supported by the wider Green Air Monitoring occupational hygiene network across related workplace exposure disciplines.
Looking for the broader assessment exercise? Workplace noise surveys combine exposure assessment with scoping, risk assessment and formal reporting. For the representative measurement programme behind exposure calculations, see workplace noise monitoring. Learn more about us or get in touch.
FAQ
Noise exposure assessment FAQs
What is a workplace noise exposure assessment?+
A workplace noise exposure assessment is a structured evaluation of how loud noise sources, task durations and employee work patterns combine to produce daily or weekly personal noise exposure. It interprets measured sound levels against the Control of Noise at Work Regulations 2005 framework — the lower and upper exposure action values and the exposure limit value — and identifies where employer action is required.
How is daily noise exposure calculated?+
Daily personal noise exposure (LEX,8h) is calculated by combining the equivalent continuous sound level (LAeq) of each task with the duration of that task across the working day, then normalising the total to a notional eight-hour reference period. Where workers move between activities, each task's contribution is weighted by its time share. Calculations follow BS EN ISO 9612 methodology.
What does LEX,8h mean?+
LEX,8h is the daily personal noise exposure level, expressed in dB(A), averaged over a notional eight-hour working day. It represents the cumulative A-weighted noise energy an individual is exposed to during their shift, normalised to eight hours so different workers and roles can be compared on a common basis.
Is a personal noise dosimeter always required?+
No. Personal dosimetry is particularly useful for mobile workers, variable tasks or shifts where area measurements cannot reasonably represent personal exposure. For stable, repetitive work in a fixed location, calibrated sound level meter measurements combined with documented task durations can be sufficient. The right combination depends on the work being assessed.
Can different tasks be combined in one exposure assessment?+
Yes. A single LEX,8h figure is built by combining the contribution of every relevant task an employee performs during their shift, including quieter activities and breaks. Each task's measured level and observed duration are combined so the assessment reflects the worker's real daily exposure rather than the noise from any single activity.
When can weekly noise exposure be used?+
Weekly personal noise exposure (LEX,40h) may be used where daily exposure varies markedly from day to day, provided regulatory conditions are met. Weekly averaging is not a general route to disregard high daily exposures: where individual days are unusually loud, or peak sound pressure action values are exceeded, those still require attention regardless of the weekly average.
What is the workplace noise exposure limit value?+
Under the Control of Noise at Work Regulations 2005, the exposure limit value is 87 dB(A) LEX,8h with a peak sound pressure of 140 dB(C). Unlike the action values, the limit value must take into account any noise reduction provided by hearing protection actually worn by the employee.
Does hearing protection reduce calculated exposure?+
Hearing protection does not change the noise the workplace produces, so it does not reduce action-value comparisons, which are based on exposure at the ear without protection. Hearing protection is taken into account when comparing exposure against the exposure limit value (87 dB(A) LEX,8h), where the protection actually achieved at the ear may be considered.
Can an exposure assessment cover several shifts?+
Yes. Where day, evening, night or weekend shifts involve different machinery, batch sizes or staffing, the assessment can include additional visits or repeated dosimetry across the relevant shifts so each pattern of work is represented. Shift coverage is agreed during scoping and reflected in the reported exposures.
How often should noise exposure be reassessed?+
Exposure should be reassessed when there is reason to believe it may have changed — for example following new machinery, process changes, layout changes, changes in work patterns or after engineering controls are installed. A periodic review is also good practice even when nothing has obviously changed, to confirm the assessment still represents current operations.
Arrange a Noise Exposure Assessment
Speak to a UK occupational noise specialist to scope your exposure assessment, agree shift coverage and arrange measurement dates. We respond to most enquiries the same working day.