Health Surveillance for Occupational Asthma: What You Need to Know (G402)
Why this matters
Occupational asthma (OA) remains a serious and preventable work-related disease. Exposure to sensitising agents in the workplace — even at low levels — may trigger asthma symptoms in susceptible individuals. Early detection and intervention are vital to prevent long-term harm. The HSE’s guidance sheet G402 provides clear, practical advice on setting up health surveillance for OA under COSHH.
For businesses across a wide spectrum — spray painters, woodworkers, lab staff, bakers, cleaners, and more — understanding G402 is a key part of meeting your legal obligations and protecting your workforce.
Key points from G402
1. What is occupational asthma and when is surveillance needed
- Occupational asthma (OA) is defined as asthma caused by exposure to substances in the work environment.
- Once sensitisation develops, even very low levels of exposure can provoke symptoms.
- Health surveillance is appropriate when:
• Workers are exposed to known asthmogens (e.g. isocyanates, wood dust, flour dust, glues)
• Substances carry a hazard label like H334 (“may cause allergy or asthma symptoms if inhaled”)
• Control relies on respirators (i.e. PPE is the main barrier)
• A confirmed OA case arises in the workforce
2. What a suitable health surveillance scheme should involve
- The scheme should be designed and overseen by a competent occupational health professional (doctor or nurse) familiar with respiratory risks.
- It must include:
• A baseline assessment before or soon after exposure begins (ideally within six weeks)
• Ongoing surveillance, typically annually (though more frequent for new or high-risk roles)
• Use of a respiratory questionnaire plus spirometry testing (lung function)
• Interpretation of results both at the individual and group (exposed workforce) level, to spot trends and triggers - Employers should appoint a responsible person (trained, supported by the occupational health expert) to help administer questionnaires and manage records.
3. Raising awareness & capturing symptom reports
- Workers should be informed of typical symptoms (e.g. wheezing, recurring cough, chest tightness, shortness of breath, runny/blocked nose) and encouraged to report them promptly — ideally via a clear reporting protocol.
- Surveillance should never replace a risk assessment or control measures; it complements them.
4. Reviewing controls in light of findings
- If any case of OA is suspected or confirmed, your risk assessment must be revisited, and controls improved (or worker moved to lower exposure role) where necessary.
- Health surveillance outcomes are an important feedback loop into your overall risk management.
5. Record keeping
- A health record must be maintained for each worker under surveillance, containing:
• Personal identifiers & exposure details
• Dates, durations, and frequency of exposure
• PPE used
• Results of questionnaire and spirometry
• Recommendations and any action taken - Records must be stored securely for at least 40 years from the last entry.
What your business should do now
- Check your processes: Do you use or handle substances known to cause OA (paints, wood dusts, enzyme cleaners, etc.)? Are you relying heavily on respirators?
- Engage an occupational health professional: If you don’t already have one, bring on board someone qualified to set up the surveillance scheme.
- Baseline your workforce: Establish a starting point for existing staff and set timelines for new starters.
- Inform & train workers: Make sure they know the symptoms, the reporting route, and why health surveillance matters.
- Review and improve controls: Use the surveillance data to feed back into risk assessments and control strategies.
- Record rigorously: Ensure health records are complete, kept secure, and retained for the legally required period.
How Outsource Safety can help
At Outsource Safety, we understand that implementing health surveillance — especially for respiratory risk — can be complex and resource-intensive. We support organisations by:
- Advising on appropriate surveillance schemes tailored to your industry and risk profile
- Liaising with occupational health professionals to deliver questionnaire + spirometry packages
- Auditing existing surveillance records and recommending improvements
- Integrating surveillance data into your broader COSHH and risk management systems
If you’d like support to review or set up an occupational asthma surveillance programme in your business, get in touch — we’d be happy to guide you through the process.
