What this is
What is a chemical exposure assessment?
What is a chemical exposure assessment?
A chemical exposure assessment evaluates a worker's exposure to a specific substance across the tasks where it is used, combining sampling or modelled data with route of entry, hazard properties and control adequacy. It concludes with a residual risk band and an acceptability decision.
Who should carry out a chemical exposure assessment?
A hygienist, or someone with equivalent training in exposure routes, sampling strategy and control evaluation. Judging whether a route is credible, and whether a control is genuinely the highest practicable, needs that background rather than task familiarity alone.
What is the difference between this and a qualitative exposure assessment?
A qualitative exposure assessment is a screening judgement made before or without sampling, used to prioritise attention. A chemical exposure assessment is the fuller evaluation for a specific substance, drawing on sampling, biological monitoring or modelling and reaching an acceptability conclusion.
Scope
When is a chemical exposure assessment required?
This assessment is the substance-specific step in the surveillance programme. Using it for a task-level screening judgement, or for a hazard that is not an airborne or dermal chemical, produces a record that will not answer the question it is asked later.
Use this template when
- A new chemical is being introduced to a task or process for the first time
- A process change alters how an existing substance is used, in what quantity, or by what method
- A complaint, incident or periodic schedule requires re-evaluation of exposure to a specific substance
- You are running the Occupational Health Surveillance programme and this is its substance-specific step
- A linked record needs this one to exist, such as a health surveillance plan or risk assessment reference
Do not use it for
- Qualitative Exposure Assessment, which is the screening judgement made before or in place of sampling, to prioritise attention rather than reach a final conclusion.
- Personal Air Sampling Record, which records a single sample result rather than the full evaluation of routes, controls and acceptability.
- Similar Exposure Group Register, which groups workers who share tasks and agents rather than assessing one substance in depth.
- Dermatitis Risk Assessment or Skin Inspection Record, where the concern is dermal irritation observed on a worker rather than the exposure assessment itself.
- Anything outside KnowHealth, which belongs in the workspace that owns that process
Compliance mapping
Which ACGIH requirements does this satisfy?
ACGIH sets the exposure benchmark and WHMIS governs how the hazard is classified and communicated; neither prescribes the assessment method, which is why the reasoning behind route and control decisions carries the defensibility.
| Clause | Requirement | Where it lands |
|---|---|---|
| ACGIH TLVs | Threshold limit values define the airborne concentration benchmark a measured or estimated result is judged against | Measured or estimated exposure |
| OSHA 1910.1200 | Safety data sheet review and hazard classification required before a hazardous chemical is used | Header |
| WHMIS, Hazardous Products Regulations | Classification of hazard properties including sensitisation, carcinogenicity and reproductive toxicity, via label and safety data sheet | Exposure characterisation |
| OSHA 1910.1000, subpart Z | Permissible exposure limits for air contaminants, applicable where no substance-specific limit is otherwise set | Measured or estimated exposure |
| ISO 45001 cl.8.1.2 | Elimination and substitution considered ahead of engineering and administrative control, with personal protective equipment last | Controls |
| OSHA 1910.134 | Respiratory protection program requirements, including fit testing where respiratory protective equipment is specified | Controls |
| OSHA 1910.1020 | Employee access to exposure and medical records generated by the assessment | Health surveillance |
What it does not cover
- Personal Air Sampling Record, which is a single sample result rather than the combined evaluation of routes, controls and acceptability.
- Qualitative Exposure Assessment, which is the screening judgement used to prioritise attention before sampling or in its absence.
- Similar Exposure Group Register, which groups workers by shared task and agent rather than assessing one substance in depth.
- Dermatitis Risk Assessment or Skin Inspection Record, which address observed dermal irritation or damage rather than the assessment that precedes it.
- Exposure Control Plan, which sets the programme-level control strategy rather than one substance's assessed exposure.
Global
Chemical Exposure Assessment requirements by country
The duty to assess chemical exposure is close to universal, but what counts as an acceptable exposure limit, and how the hazard must be classified and communicated, differs by jurisdiction.
OSHA 1910.1200 (Hazcom) and 1910.1000 (air contaminants)
Hazard communication requires SDS review and classification before use; permissible exposure limits apply where no substance-specific standard exists.
An assessment silent on whether the SDS was reviewed, or which limit applied, cannot show it addressed the substance as legally required.
WHMIS, Hazardous Products Regulations
Classifies hazard properties including sensitisation, carcinogenicity and reproductive toxicity via labels and safety data sheets, with provincial exposure limits applied alongside.
The hazard classes named in WHMIS are exactly the properties this assessment's characterisation fields capture, and skipping them skips a legally classified hazard.
ACGIH threshold limit values
Widely adopted guidance benchmark for airborne concentration, referenced into law in many jurisdictions despite ACGIH being a voluntary body.
Where no local limit exists, the TLV is usually the fallback benchmark, and the assessment should state explicitly when that is the basis used.
How to complete it
How to complete a chemical exposure assessment, step by step
The template scores routes, controls and a residual band. What determines whether the conclusion is sound is the judgement behind which basis produced it and whether every credible route was actually weighed.
Inhalation, skin and ingestion are scored separately because a substance can be low risk by one route and high by another. A sensitiser or a substance with skin notation can fail on dermal grounds alone, regardless of how clean the air result looks.
Personal sampling and biological monitoring carry more weight than modelling, and modelling more than analogy or judgement alone. A judgement-only conclusion should be treated as provisional, with a stated plan to sample.
A substance without a listed exposure limit still carries whatever hazard properties are on its safety data sheet. Record what is known independent of the limit, rather than treating an absent number as an absent concern.
The highest control level actually applied should be supported by a stated reason the higher levels were rejected, not just recorded as a category. Landing on PPE with no note why engineering control was impractical documents an outcome, not a decision.
What auditors find
Most common chemical exposure assessment findings
Findings tend to concentrate where a single reassuring figure stood in for the full picture the assessment was meant to build.
| Finding | Clause | What fixes it |
|---|---|---|
| Safety data sheet not reviewed before the assessment was carried out. | OSHA 1910.1200 | Require SDS review as a completed, dated step before the exposure characterisation fields are populated. |
| Skin route not meaningfully evaluated for a substance carrying a skin notation. | WHMIS, Hazardous Products Regulations | Flag any substance with a skin notation and require the skin route field to be substantively justified, not defaulted. |
| Assessment basis recorded as judgement only where personal sampling was practicable. | ACGIH TLVs | Require a stated reason sampling was not used, and set a plan and date to obtain a measured result. |
| Highest control level defaults to PPE with no evidence elimination or substitution was considered. | ISO 45001 cl.8.1.2 | Require a documented reason each higher control level was rejected before PPE is accepted as the conclusion. |
| Respiratory protective equipment specified with no fit test reference attached. | OSHA 1910.134 | Make the fit test reference a required field wherever respiratory protective equipment is marked required. |
| Sensitiser or carcinogen identified but no health surveillance requirement triggered. | OSHA 1910.1020 | Link sensitiser, carcinogen and reproductive hazard flags directly to the surveillance requirement field. |
Case in point
Case in point: the sample that was clean and the route that was not
A cleaning products manufacturer assessed exposure to an enzyme-based sanitiser used in a filling task. Personal air sampling returned a result under ten percent of the exposure limit, and the assessment concluded exposure was acceptable, noting gloves as the control in place.
A worker on that task developed an allergic skin reaction within the year and was confirmed sensitised to the enzyme. The safety data sheet had carried a sensitiser classification from the outset, and the glove in use had a breakthrough time shorter than the task duration, recorded as a field but never checked against actual wear time.
The template
The template, field by field
The form exactly as it installs. Every field, option, score and conditional rule is editable, and the links to other templates come with it.
6 sections
- Reference
- HLT-006
- Archetype
- Assessment
- Record ID
- EXP-2026-000
- Scoring
- AIHA category
- Direction
- High is bad
- Singleton
- No
- Basis
- ACGIH, WHMIS
- Links
- Links Substance, SEG
- Tags
- Hygiene, Chemical
- Sections
- 6
- Fields
- 56
- Follow up fields
- 5
- Repeating sections
- 0
- Links out
- 9
Header
15 fieldsAssessment ID*
Auto sequence. Format CEA-2026-000.
The record's own ID. Other templates point at this value.
Status*
Drives who this goes to next.
- Planned2 pts
- In progress2 pts
- Complete3 pts
- Deferred0 pts
- Open0 pts
- Closed3 pts
- Overdue0 pts
Date and Time*
Completed By*
Site*
Site ID*
Format SITE-000.
Links to FDN-001 Site ID
Worker*
Person ID*
Format PER-0000.
Links to FDN-003 Person ID
Substance*
Substance ID*
Format SUB-0000.
Links to FDN-006 Substance ID
Task*
Job ID*
Format JOB-000.
Links to FDN-004 Job Task ID
Assessment Trigger*
SDS Reviewed*
- Yes3 pts
- No0 pts
Exposure Limit Exists*
- Yes3 pts
- No published limit1 pt
Exposure characterisation
9 fieldsForm Used*
Powder, liquid, aerosol, gas or vapour. Form determines route and control.
- Solid pellet4 pts
- Liquid2 pts
- Powder1 pt
- Aerosol0 pts
- Gas or vapour0 pts
Concentration Used*
Quantity Per Shift
Inhalation Route*
- Not credible4 pts
- Low3 pts
- Medium1 pt
- High0 pts
Skin Route*
Skin notation on the exposure limit means air sampling alone underestimates total dose.
- Not credible4 pts
- Low3 pts
- Medium1 pt
- High0 pts
Ingestion Route*
- Not credible4 pts
- Low3 pts
- Medium1 pt
- High0 pts
Sensitiser*
Sensitisers have no safe level once somebody is sensitised. Enzyme cleaners and some sanitisers qualify.
- No3 pts
- Yes0 pts
Carcinogen Or Mutagen*
- No3 pts
- Yes0 pts
Reproductive Hazard*
- No3 pts
- Yes0 pts
Measured or estimated exposure
5 fieldsAssessment Basis*
Personal sampling is strongest. Modelling and analogy are acceptable where sampling is impractical.
- Personal sampling4 pts
- Biological monitoring4 pts
- Modelling2 pts
- Analogy with similar task1 pt
- Judgement only0 pts
Sample ID
Links to HLT-003 Sample ID
Result Versus Limit*
- Under 10 percent4 pts
- 10 to 50 percent3 pts
- 50 to 100 percent1 pt
- Over limit0 pts
Biological Monitoring Available
- Yes3 pts
- No1 pt
Biological Monitoring Result
Controls
11 fieldsElimination Considered*
- Yes3 pts
- No0 pts
Substitution Considered*
- Yes3 pts
- No0 pts
Substitution Assessed For New Hazards
Substitutes sometimes trade a known hazard for an unstudied one.
- Yes3 pts
- No0 pts
Enclosure Or Automation*
- Fully applied4 pts
- Partly2 pts
- None0 pts
Local Exhaust Ventilation*
- Effective and tested4 pts
- Present, untested2 pts
- None0 pts
LEV Test Current
- Yes3 pts
- Overdue0 pts
Highest Control Level Applied*
- Eliminate4 pts
- Substitute4 pts
- Engineer3 pts
- Separate or isolate3 pts
- Administrative1 pt
- PPE0 pts
RPE Required*
- No3 pts
- Yes1 pt
Fit Test ID
Links to HLT-031 Record ID
Skin Protection Specified*
- Yes3 pts
- Not required3 pts
- No0 pts
Glove Breakthrough Time Checked
Chemical gloves have a stated breakthrough time. Beyond it the glove is worse than nothing.
- Yes3 pts
- No0 pts
Health surveillance
3 fieldsHealth Surveillance Required*
Surveillance Type
Plan ID
Links to HLT-009 Plan ID
Outcome
13 fieldsResidual Band*
- Low, 1 to 45 pts
- Medium, 5 to 94 pts
- High, 10 to 142 pts
- Very high, 15 to 191 pt
- Extreme, 20 to 250 pts
Exposure Acceptable*
- Yes3 pts
- Marginal1 pt
- No0 pts
Reassessment Interval*
Risk Assessment
Risk ID
Format RSK-2026-00000.
Links to FDN-012 Risk ID
Action Required*
Raise the action record, then enter its reference here.
- No2 pts
- Yes0 pts
Priority
- High0 pts
- Medium1 pt
- Low3 pts
CAPA ID
Format CAPA-2026-00000.
Links to FDN-014 CAPA ID
Action Owner
Occupational Hygienist*
Signature*
Safety Lead*
Second Signature*
HLT-006 · record IDs look like EXP-2026-000 · Links Substance, SEG
Open in KnowellaRun it with agents
From a document you fill in to a programme that runs itself
The assessment produces a residual band and a control decision. What fails around it is the follow-through: the fit test never referenced, the surveillance trigger never raised, the reassessment nobody scheduled.
Holds the assessment library against the substance and worker registers, and flags a sensitiser or carcinogen finding that has not been linked to a health surveillance requirement.
Checks that the highest control level applied is supported by a stated reason the higher hierarchy levels were rejected, rather than accepting the outcome alone.
Connects a required respiratory or skin control to the fit testing and glove selection records it depends on, so the control is specified and evidenced.
Watches substance introductions and process changes for the trigger that should raise a reassessment, rather than waiting for the stated interval.
This template lives in KnowHealth — employee wellbeing. Exposure monitoring, health surveillance, case management and return to work.
Meet KnowHealth→Glossary
Chemical Exposure Assessment definitions and key terms
- Threshold limit value
- ACGIH's recommended airborne concentration a worker can be exposed to without adverse effect, used as the benchmark against a measured or estimated result.
- Skin notation
- A designation on a substance's data indicating that dermal absorption contributes meaningfully to total dose, meaning air sampling alone underestimates exposure.
- Sensitiser
- A substance capable of inducing an allergic response after exposure, after which even very low subsequent exposure can trigger a reaction; there is no established safe level once sensitised.
- Assessment basis
- The method used to characterise exposure: personal sampling, biological monitoring, modelling, analogy with a similar task, or judgement alone, ranked in roughly that order of reliability.
- Breakthrough time
- The stated duration a chemical protective glove or garment resists permeation by a specific substance, beyond which it no longer provides meaningful protection.
FAQ
Frequently asked questions about chemical exposure assessment
What if there is no published exposure limit for the substance?+
Assess the hazard from what is known independent of a limit: its classification, sensitising or carcinogenic properties, and the routes by which it can enter the body. No published limit records the ceiling as unknown, not the risk as absent.
Does a clean air sample mean the substance is safe to use as is?+
Only for the inhalation route. A substance with a skin notation, or sensitising, carcinogenic or reproductive hazard properties, needs those routes assessed on their own terms.
How is exposure basis chosen when sampling is impractical?+
Modelling or analogy with a closely similar task are acceptable substitutes, in that order of preference, but the assessment should record why sampling was not used and treat the conclusion as provisional.
What does the hierarchy of controls mean for a chemical assessment specifically?+
Elimination and substitution considered before engineering controls such as enclosure or local exhaust ventilation, which rank above administrative controls and respiratory or skin protection. Each level should be shown as weighed, not just recorded.
When does a chemical exposure assessment trigger health surveillance?+
Where the substance is a sensitiser, carcinogen or reproductive hazard, or the route and level indicate a health effect worth monitoring for. The trigger should follow directly from the hazard properties identified earlier, not be decided separately.
How often should a chemical exposure assessment be repeated?+
Whenever the process, quantity, method or control arrangement changes materially, and at whatever periodic interval the local programme sets as a backstop. A substitution trading one hazard for an unstudied one is itself a trigger for reassessment.
Keep going
Related templates and programmes
Industries this is written for
Programmes this belongs to
Used together in Occupational Health Surveillance
Similar Exposure Group Register
Groups workers who share the same tasks, agents and exposure patterns
Qualitative Exposure Assessment
Rates likely exposure using professional judgement, task knowledge and existing data, before any sampling
Personal Air Sampling Record
Records a sample taken from a worker's breathing zone over a shift
Area Monitoring Record
Records fixed point sampling in a work area rather than on a person
Noise Dosimetry Record
Records a worker's noise exposure over a full shift using a personal dosimeter
Exposure Result Review
Reviews sampling results statistically across a group, rather than judging single samples
More in Exposure Monitoring
Similar Exposure Group Register
Groups workers who share the same tasks, agents and exposure patterns
Qualitative Exposure Assessment
Rates likely exposure using professional judgement, task knowledge and existing data, before any sampling
Personal Air Sampling Record
Records a sample taken from a worker's breathing zone over a shift
Area Monitoring Record
Records fixed point sampling in a work area rather than on a person
Noise Dosimetry Record
Records a worker's noise exposure over a full shift using a personal dosimeter
Exposure Result Review
Reviews sampling results statistically across a group, rather than judging single samples
Written and reviewed by
Siddarth Singh
Founder & Chief Executive Officer, Knowella
Certified Safety Professional and industrial and systems engineer with more than a decade inside food supply chain, freight and manufacturing operations. This page was written against the current text of the standards it cites, not against secondary summaries of them.
- Certified Safety Professional (CSP), Board of Certified Safety Professionals
- MBA, University of Chicago Booth School of Business
- MS and BS, The Ohio State University, Industrial and Systems Engineering
- Six Sigma Black Belt
Sources and last review. Reviewed 16 August 2026 against:
- ACGIH — Threshold Limit Values and Biological Exposure Indices
- WHMIS — Hazardous Products Regulations (Canada)
- OSHA 1910.1200 — Hazard Communication
- OSHA 1910.1000, subpart Z — Air contaminants
- OSHA 1910.134 — Respiratory Protection
This page is general guidance, not legal advice. Confirm requirements with your jurisdiction’s regulator.