Occupational Health and Hygiene
Domain 7 tests the classic hygiene sequence and whether you can apply exposure limits and surveillance to construction health risks.
The sequence
Anticipate the hazard before work starts, recognise it on site, evaluate exposure by measurement, then control and verify.
Exposure limits
Long-term limits are usually 8-hour time-weighted averages; short-term limits cover around 15 minutes. Measured personal exposure is compared with the limit, not with a static background reading. Personal sampling on representative workers gives the defensible number.
Key construction exposures
- Respirable crystalline silica: water suppression, on-tool extraction, fit-tested RPE, health surveillance.
- Noise: action values commonly at 80 and 85 dB(A) over 8 hours with a 3 dB exchange rate; hearing protection zones and audiometry.
- Hand-arm vibration: control by tool choice and trigger time; surveillance for early symptoms.
- Manual handling: assess task, individual, load and environment.
- Heat stress: acclimatisation, fluids, rest cycles.
Worked example
A worker uses a grinder to chase concrete for four hours. Reasoning: personal sampling shows respirable dust above the workplace limit; controls applied in hierarchy order are water suppression and on-tool extraction, then RPE with fit testing, plus zoning and cleaning; repeat sampling confirms the effect; health surveillance follows because exposure is significant.
Traps
Assuming compliance with an exposure limit means no risk; relying on RPE without fit testing or face-fit checks; using static sampling to judge personal exposure; forgetting skin absorption and ingestion routes; putting medical surveillance results in the general personnel file.