HSE reports an estimated 52 new occupational asthma cases through specialist surveillance in 2024. Historical epidemiological studies suggest a much larger underlying burden. These measures cover different populations and should not be treated as interchangeable counts.
Occupational asthma can result from sensitisation to a substance at work or from irritant exposure. Flour and isocyanates are recognised causes. This guide distinguishes Great Britain’s HSE statistics, specialist THOR/SWORD surveillance and Industrial Injuries Disablement Benefit assessments from older epidemiological estimates.
Key facts and figures
- 9–15% of working-age asthma was attributed to occupational factors in the historical epidemiological studies cited by HSE.
- 7,500–9,000 annual cases in Great Britain are implied by a historical European incidence estimate; this is not a current measured total.
- 52 estimated new occupational asthma cases in 2024 from THOR/SWORD specialist reporting, compared with 94 in 2023.
- 35 new occupational asthma cases were assessed for Industrial Injuries Disablement Benefit in 2024, against a ~73-a-year average across 2010–2019.
- 22,000 new self-reported work-related breathing or lung problems a year, averaged over 2022/23–2024/25; this includes conditions other than asthma.
- 5 of the 35 IIDB asthma assessments in 2024 were attributed to flour or isocyanates.
- 40% of reported occupational asthma cases in 2020–2024 were in Skilled Trades Occupations, up from 34% in 2010–2019.
- 3.24% annual decline estimated by the THOR model for 2010–2024, with important uncertainty about changing reporting.
Checked on 15 October 2026 against HSE’s 2025 statistical releases. The specialist and benefit figures relate to 2024; survey figures use multi-year averages. Historical studies are identified separately.
How many people get occupational asthma in the UK each year?
HSE cites historical epidemiological studies estimating that occupational factors account for 9–15% of asthma in adults of working age. A European study estimated annual incidence at 25–30 cases per 100,000, implying roughly 7,500–9,000 cases in Great Britain. These are older research estimates used to illustrate the potential burden, not a direct count or a new 2026 estimate.
THOR/SWORD specialist reports produced an estimated 52 new occupational asthma cases in 2024, compared with 94 in 2023. HSE cautions that these figures substantially underestimate incidence. The scheme depends on referral to participating specialists and reporting, and its sampling adjustment does not capture every affected worker.
| Measure | Figure | Data period |
|---|---|---|
| Share of adult working-age asthma caused by work | 9–15% | Historical epidemiological studies cited by HSE |
| Implied new work-related asthma cases, Great Britain | ~7,500–9,000 a year | Historical European study; not a current count |
| New occupational asthma cases reported by chest physicians | 52 | 2024 (THOR/SWORD) |
| New occupational asthma cases assessed for IIDB | 35 | 2024 (IIDB01) |
| Average IIDB assessments a year | ~73 | 2010–2019 average |
What do the self-reported and benefit figures show?
The Labour Force Survey estimates 22,000 new self-reported work-related breathing or lung problems a year, averaged over 2022/23–2024/25 (95% confidence interval 14,000–30,000). Among people who worked in the previous year, estimated prevalence was 49,000 (36,000–61,000), or about 140 per 100,000 workers, using the same period. These are broad respiratory categories and cannot be read as asthma counts.
There were 35 new occupational asthma assessments for IIDB in 2024, compared with 30 in 2023 and an annual average of about 73 in 2010–2019. Assessment counts are not identical to benefit awards. The scheme covers prescribed diseases and occupations and has eligibility conditions; the figures should not be combined with specialist or survey estimates.
What is the most common cause of occupational asthma at work?
Flour and isocyanates were the two most commonly reported agents before 2020 and continue to be commonly cited by HSE. Together they accounted for 5 of the 35 IIDB asthma assessments in 2024. Isocyanates occur in some two-pack paints, foams and coatings; flour exposure occurs in bakeries and food manufacture. Sensitisation can make very low subsequent exposure harmful, so prevention and suitable controls are essential.
Other recognised asthmagens include glutaraldehyde, latex and colophony in rosin-based solder flux. Welding fume, metalworking-fluid mist and wood dust also present respiratory risks. Assess both supplied substances and those generated by the work: generated dust or fume may have no supplier safety data sheet.
Which jobs have the highest risk of occupational asthma?
Vehicle paint technicians, bakers and flour confectioners, fishmongers and poultry dressers, and welding trades had high specialist-reported rates in 2010–2019. HSE continues to identify these exposures as important, but small recent case counts and reporting changes make a current occupation ranking unreliable.
The trade-level rates make the small-number caution unavoidable. Bakers and flour confectioners had an occupational-asthma incidence of 35.5 per 100,000 workers a year in 2010–2019, falling to 6.1 per 100,000 in 2020–2024 — but that fall is based on only around 12 versus 2 estimated cases a year, so year-to-year movement should be read with care. At the broad occupational-group level the picture is steadier: Skilled Trades Occupations made up 40% of reported occupational asthma cases in 2020–2024, up from 34% in 2010–2019, while Process, Plant and Machine Operatives fell to 19% (from 29%).
| Occupation / group | Figure | Data period |
|---|---|---|
| Bakers and flour confectioners — incidence rate | 35.5 per 100,000/yr | 2010–2019 (THORR04) |
| Bakers and flour confectioners — incidence rate | 6.1 per 100,000/yr | 2020–2024 (small numbers) |
| Skilled Trades Occupations — share of cases | 40% | 2020–2024 |
| Skilled Trades Occupations — share of cases | 34% | 2010–2019 |
| Process, Plant & Machine Operatives — share | 19% | 2020–2024 (was 29%) |
Manufacturing has a higher specialist-reported asthma rate than the all-industry average. The 2010–2019 data identified high rates in food products, motor vehicles, chemicals, basic metals and some other manufacturing activities. These historical comparisons do not establish an unchanged ranking for 2020–2024.
Who develops occupational asthma — and at what age?
HSE’s 2025 report describes cases across working ages, with 18% aged 25–34, 17% aged 35–44, 26% aged 45–54 and 28% aged 55–64 in its THOR age profile. This distribution describes reported cases; it does not by itself establish age-specific risk or explain when exposure or symptoms began.
THOR/SWORD estimated 473 new occupational respiratory disease cases in 2024. About 14% were shorter-latency conditions such as asthma and hypersensitivity pneumonitis, while most were long-latency diseases. This specialist-reported case total is separate from annual deaths or the Labour Force Survey estimate.
Is occupational asthma rising or falling?
The THOR model estimated an annual change of −3.24% across 2010–2024 (95% confidence interval −5.63% to −0.78%). HSE warns that reporting fatigue and pandemic disruption complicate interpretation and cannot be fully adjusted for. Its assessment is that current incidence may be similar to the period before 2019; the fall in reports should not be presented as proof of an equivalent fall in disease.
Prevention still requires avoiding exposure where reasonably practicable and otherwise adequately controlling it through substitution, enclosure and extraction, with suitable RPE where necessary. Health surveillance can help identify early effects where the COSHH criteria apply. These controls are justified by the hazards, rather than by an assumed explanation for the reporting trend.
| Trend measure | Figure | Data period |
|---|---|---|
| Modelled change in occupational asthma incidence | -3.24% a year | 2010–2024 (THOR model) |
| Chest-physician cases (THOR/SWORD) | 94 → 52 | 2023 → 2024 |
| IIDB assessments | 30 → 35 | 2023 → 2024 |
| Work-related breathing/lung problem rate | ~200 → ~140 per 100,000 | Early 2000s versus 2022/23–2024/25 average |
Is occupational asthma covered by COSHH, and what does it cost?
Substances causing occupational asthma fall within COSHH. For an asthmagen, adequate control includes reducing exposure as low as reasonably practicable, applying the control principles and observing any WEL. Assess the need for health surveillance under Regulation 11; it is not automatically the same programme for every exposed worker.
A 2011 study estimated £70–100 million in lifetime costs for a cohort developing occupational asthma in 2003, using 2004 prices. In that historical model, individuals bore about 49%, the state 48% and employers 3%. This is not a current annual cost. IIDB may be available subject to its conditions. RIDDOR reporting applies when the diagnosis and significant or regular exposure to a known respiratory sensitiser meet the specified criteria.
Frequently asked questions
How many people get occupational asthma in the UK each year?
THOR/SWORD estimated 52 new cases through specialist reports in 2024, while IIDB recorded 35 new assessments. Neither is a complete population count. The much larger 7,500–9,000 annual estimate cited by HSE comes from historical epidemiological research, rather than a current direct measurement.
What is the most common cause of occupational asthma at work?
Flour and isocyanates were the most commonly reported agents before 2020 and remain commonly cited by HSE. Together they accounted for 5 of 35 IIDB asthma assessments in 2024. These small counts do not establish a complete current ranking of all causes.
Which jobs have the highest risk of occupational asthma?
Historical 2010–2019 surveillance identified high rates in vehicle painting, baking, fish and poultry preparation, and welding. Skilled Trades Occupations accounted for 40% of specialist-reported cases in 2020–2024. Recent detailed rates involve small numbers and should be interpreted cautiously.
Is occupational asthma covered by COSHH, and can you claim compensation?
COSHH requires assessment and prevention or adequate control of exposure to asthma-causing substances, with health surveillance where its criteria apply. IIDB has prescribed disease, occupation and disablement conditions. RIDDOR reporting requires a diagnosis and the specified significant or regular exposure to a known respiratory sensitiser.
Related guides
- COSHH Statistics UK: Hazardous Substances at Work
- Welding Fume Statistics UK: Exposure & Lung Disease
- Metalworking Fluid Statistics UK: Mist & Respiratory Risk
- Wood Dust Statistics UK: Exposure, Asthma & Cancer
- What Substances Are Covered by COSHH? (And What Isn’t)
Sources & references
- HSE: Work-related asthma statistics, 2025
- HSE: Occupational lung disease statistics, 2025
- HSE THORR04: occupational asthma by occupation
- HSE THORR05: occupational asthma by industry
- HSE: occupational asthma
- HSE: reportable occupational diseases
- GOV.UK: Industrial Injuries Disablement Benefit
- Ayres and colleagues: lifetime costs of the 2003 occupational asthma cohort, published 2011
- HSE: COSHH Approved Code of Practice
Make sure your team can recognise respiratory sensitisers like isocyanates and flour dust and apply the right controls before exposure causes asthma.
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Mark writes about workplace health & safety, COSHH and accredited online training for COSHH Training, part of Online CPD Academy.