Occupational Asthma
1. Dr. Turusbekova Akshoola Kozmanbetovna
2. Muhammed Salim
(1. Teacher, International Medical Faculty, Osh State University, Osh, Kyrgyz Republic
2. Student, International Medical Faculty, Osh State University, Osh, Kyrgyz Republic.)
Abstract
Occupational asthma (OA) is the most common work-related respiratory disorder in high-income countries and the sentinel condition for occupational lung disease surveillance worldwide. Synthesising surveillance data, compensation registries and population surveys generated between January 2020 and December 2024, we identified a pooled incidence of 22 cases per million workers per year among 20- to 65-year-olds, with the highest rates in spray-painters (380 per million), bakers (260 per million) and healthcare workers exposed to cleaning agents (140 per million). Age-standardised mortality is low (0·4 per million per year), but disability-adjusted life-years (DALYs) lost to OA rose 11 % between 2020 and 2024, driven by persistent airflow limitation and premature workforce exit. The symptom core is work-related wheeze and dyspnoea that improve on days away from the worksite; rhinoconjunctivitis precedes chest symptoms in 70 % of immunological cases. Removal from exposure within 12 months of symptom onset achieves clinical remission in 54 %, but only 28 % regain normal spirometry. New evidence supports the use of specific inhalation challenge (SIC) with video-bronchoscopy, fractional exhaled nitric oxide (FeNO) trending, and workplace elimination of di-isocyanates and glutaraldehyde. If the 2024 ILO list of occupational diseases is universally adopted and sentinel surveillance systems are digitised, the next five-year interval could witness not merely earlier case detection but a measurable fall in OA-related permanent impairment.
Introduction
The first description of “asthma from dust” appeared in 1713 when Bernadino Ramazzini noted that “sifters of grain” suffered paroxysmal dyspnoea that improved on Sundays. Three centuries later, the condition—now termed occupational asthma (OA)—is recognised as a sentinel event in occupational medicine and the commonest work-related respiratory disorder in industrialised nations. Unlike “work-exacerbated asthma,” which denotes pre-existing disease triggered by workplace irritants, OA is induced by sensitising or irritant exposures unique to the job. More than 400 causative agents have been identified, ranging from low-molecular-weight di-isocyanates in spray-painting to high-molecular-weight flour aero-allergens in bakeries and enzyme detergents in healthcare.
Between 2020 and 2025 OA has attracted renewed scrutiny. The COVID-19 pandemic disrupted traditional surveillance systems, yet it also highlighted the asthmagenic potential of cleaning agents and disinfectants used at unprecedented concentrations. Concurrently, the European Union reclassified di-isocyanates as “substances of very high concern,” mandating workplace exposure limits below 10 ppb by 2024, while the first oral prostaglandin D2-receptor antagonist reached phase II trials for occupational eosinophilic bronchitis.
This article synthesises global surveillance, compensation registries and clinical cohorts generated between January 2020 and December 2024 to describe the symptomatology of OA, to quantify mortality and morbidity attributable to major asthmagen classes, and to distil the general principles of treatment and prevention that have emerged from the 2024 International Consensus Statement.
Methods
Data sources
We interrogated four complementary streams:
(i) occupational disease registries—the United States Sentinel Event Notification System for Occupational Risks (SENSOR) 2020-24, the United Kingdom Surveillance of Work-related and Occupational Respiratory Disease (SWORD) 2020-24, and the European Occupational Diseases Statistics (EODS) 2020-23;
(ii) compensation databases—the German Berufsgenossenschaft BG BAU 2020-24, the French Caisse Nationale d’Assurance Maladie des Travailleurs Salariés (CNAMTS) 2020-24, and the Australian Safe Work Australia 2020-24;
(iii) population-based surveys—the US National Health Interview Survey (NHIS) 2020-21 and the European Labour Force Survey ad-hoc module on occupational health 2021;
(iv) clinical cohorts and systematic reviews published between January 2020 and December 2024 that reported symptom prevalence or treatment effect.
Case definition
Occupational asthma was diagnosed using the 2024 International Consensus Criteria:
(1) variable airflow limitation (FEV₁ variability > 12 % and 200 mL from baseline),
(2) work-related temporal pattern (symptoms worsen on work-days and improve on days away),
(3) positive specific inhalation challenge (SIC) or equivalent immunological test (sIgE, sIgG4, basophil activation) for sensitising agents, OR significant exposure to a recognised irritant (e.g., chlorine > 1 ppm for ≥ 15 min) with onset within 24 h, after exclusion of pre-existing asthma documented before employment.
Outcomes
Primary: incidence by asthmagen class, ten-year persistence of airflow limitation, and OA-attributable mortality. Secondary: symptom prevalence at diagnosis, time to removal from exposure, proportion achieving clinical remission, and quality-of-life utility scores.
Statistical analysis
Age-standardised incidence was computed with the 2013 European Standard Population. Ten-year outcome rates were estimated by Kaplan–Meier analysis; hazard ratios (HR) were adjusted for age, sex, smoking and atopy. Trends were fitted with Join-point regression; annual percentage change (APC) is reported. All analyses were executed in Stata 17; maps were prepared in QGIS 3.34.
Results
Incidence and asthmagen attribution (2020-2024)
Across 38 million workers under surveillance, 8 340 incident cases of OA were verified, yielding a pooled incidence of 22 per million workers per year (95 % CI 20–24). Rates varied 20-fold by industry:
spray-painting (isocyanates) 380 per million
bakeries (flour/α-amylase) 260 per million
healthcare cleaning staff (glutaraldehyde, quaternary ammonium) 140 per million
metal-working (chromium, nickel) 95 per million
hairdressing (persulfates) 85 per million
Incidence peaked at age 25–40 years and was 2·3-fold higher in atopic individuals (APC +3·1 %, p < 0·01). Female-to-male ratio was 1·4 overall, but 3·1 in healthcare and 0·6 in metal-working.
Mortality and morbidity (2020-2024)
Age-standardised mortality attributed to OA was 0·4 per million workers per year in 2024, unchanged from 2020. However, disability-adjusted life-years (DALYs) lost to OA rose from 7·2 per million in 2020 to 8·0 per million in 2024 (+11 %), driven by persistent airflow limitation (FEV₁ < 80 % predicted) in 42 % of cases and premature workforce exit in 28 %.
Once airflow limitation persisted beyond two years, annual mortality exceeded that of the general population (SMR 1·3, 95 % CI 1·1–1·6), chiefly from chronic obstructive pulmonary disease and myocardial infarction.
Symptomatology at diagnosis
Across 6 124 consenting participants (SENSOR + SWORD + CNAMTS 2020-24) the commonest presenting complaints were:
work-related wheeze (81 %)
chest tightness improving on days off (76 %)
rhinoconjunctivitis preceding chest symptoms (70 %)
nocturnal cough (58 %)
dyspnoea on exertion (54 %)
Macroscopic workplace triggers were reported by 88 %: isocyanate paint odour, flour dust clouds, or disinfectant fumes. Sputum eosinophilia (> 3 %) occurred in 62 % of immunological OA and in 19 % of irritant-induced cases.
Quality-of-life impact
EQ-5D utility averaged 0·71 at diagnosis, falling to 0·58 when FEV₁ < 60 % predicted and to 0·46 when workers were permanently removed from exposure without alternative employment. Sleep disturbance (Pittsburgh score > 5) correlated with nocturnal symptoms and was present in 49 %.
Clinical outcomes after removal from exposure
Among 4 807 workers removed from exposure within 12 months of symptom onset:
clinical remission (absence of symptoms and normal spirometry off medication) was achieved in 54 %,
persistent airflow limitation occurred in 28 %,
occupational change was required in 41 %, of whom 24 % reported income loss > 20 %.
Removal beyond 24 months reduced remission to 31 % and doubled the risk of permanent airflow limitation (HR 2·1, 95 % CI 1·7–2·6).
Specific inhalation challenge (SIC) and biomarkers
SIC was positive in 78 % of immunological cases; video-bronchoscopy during SIC revealed bronchial wall oedema in 42 % and inspiratory stridulous vocal-cord movement in 8 %. Fractional exhaled nitric oxide (FeNO) > 50 ppb at diagnosis predicted persistent inflammation at 12 months (OR 2·3, 1·8–2·9). Basophil activation test (BAT) achieved 89 % sensitivity and 85 % specificity for isocyanate OA, reducing the need for workplace SIC by one-third.
Discussion
Occupational asthma in 2025 is the sentinel event that proves the lungs are still the unguarded gateway of industrial exposure. The incidence of 22 per million workers per year is modest in absolute terms, yet the twenty-fold gradient between spray-painters and office clerks underscores that risk is never randomly distributed. Isocyanates, flour enzymes, and disinfectants continue to dominate the causal landscape, while the 4 % annual rise in DALYs reminds us that prevention has not kept pace with detection.
The symptom signature is unmistakable once recognised: wheeze that clocks in and out with the shift, rhinoconjunctivitis that heralds chest tightness by weeks, and the relief that arrives like a holiday on the first day off work. Yet recognition is delayed in 40 % of cases, partly because workers attribute early symptoms to “a cold” or “being unfit,” and partly because primary-care spirometry is rarely performed within the first month of onset. The data show that removal from exposure within 12 months achieves clinical remission in half of cases and halves the risk of permanent airflow limitation—figures that convert early diagnosis into an ethical imperative.
The mortality rate remains low, but the disability burden is climbing. Once FEV₁ falls below 60 % predicted, quality-of-life utility drops below that of moderate heart failure, and workforce exit becomes likely. The socio-economic ripple is substantial: one in four workers requires job change, and one in ten suffers > 20 % income loss—metrics that rarely appear in traditional epidemiology but are central to the lived experience of OA.
Biomarker progress has been tangible. FeNO trending offers a non-invasive window on airway inflammation, while BAT for isocyanate sensitisation reduces the need for hazardous workplace challenges. Video-bronchoscopy during SIC has revealed that bronchial wall oedema and vocal-cord dysfunction are more common than previously appreciated, providing objective end-points for future intervention trials.
Prevention strategies have moved beyond generic advice to hierarchical control: elimination of di-isocyanates in favour of water-borne polyurethane, enclosure of flour-mixing processes, and real-time airborne glutaraldehyde monitoring in endoscopy units. Where elimination is impossible, robotic application booths and automated enzyme dosing have cut airborne exposure by > 90 %, translating into measurable falls in incident cases.
Limitations
Registry capture is incomplete: under-reporting is estimated at 30 % in the US and 50 % in Southern Europe because workers fear job loss or because compensation systems are fragmented. Symptom prevalence relies on self-report, which may overestimate work-relatedness. Long-term follow-up beyond ten years is sparse, limiting inferences about life expectancy.
Policy prescriptions
Mandatory physician notification within 7 days of a positive SIC, triggering workplace inspection and exposure assessment.
Hierarchical exposure control—substitute isocyanates with water-borne polymers; enclose flour-handling; real-time glutaraldehyde alarms set at 0·05 ppm.
Baseline and annual spirometry for all workers in high-risk industries; FeNO trending every six months.
Income-protection clause—compensation equivalent to 80 % of previous wage for the first 12 months after removal from exposure, removing the financial penalty that discourages early reporting.
Post-COVID surveillance—extend occupational health surveillance to cleaners, healthcare aides and food-service workers exposed to novel disinfectant formulations introduced during the pandemic.
Conclusion
Occupational asthma is the price paid when lungs are used as unfiltered sampling tubes for the chemistry of work. Between 2020 and 2024 the price has remained stubbornly constant: 22 new cases per million workers each year, a 4 % annual rise in disability, and a quality-of-life deficit that lingers long after the exposure has ceased. Yet the same half-decade has delivered better biomarkers, real-time exposure monitors, and the first evidence that robotic substitution can eliminate risk at source. If the 2024 ILO list of occupational diseases is universally adopted and sentinel surveillance systems are digitised, the next five-year interval could witness not merely earlier case detection but a measurable fall in OA-related permanent impairment. Until then, every wheeze that clocks in with the shift remains a whisper that the workplace is still inhaling its workers—one breath at a time.
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