Occupational Health and Environmental Practices
Occupational Health and Environmental Practices
This domain tests how workplace conditions affect health and how a technician controls them: noise, illumination, heat, dust and fume, chemical handling, ergonomics and waste disposal. Expect questions giving a measured exposure and asking whether it is acceptable, or asking where a particular waste stream must go.
Limits worth memorising
- Noise: the 8-hour limit is 90 dB(A). Under the equal-energy rule a 3 dB rise halves the permitted time (95 dB → 4 h, 100 dB → 2 h). Hearing protection becomes mandatory once the limit is exceeded.
- Illumination: general workshop work about 200–300 lux, precision inspection 500–1000 lux. Glare and shadow cause as many errors as low level.
- Dust: silica from grinding causes silicosis; welding fume causes metal-fume fever. Local exhaust ventilation is an engineering control and beats a disposable mask.
- Heat: comfort band roughly 20–27 °C and 40–60 % RH; heat stress needs fluid, rest cycles and acclimatisation.
Chemicals and environment
Read the SDS before use - it gives hazard class, PPE, first aid and spill response. Store acids apart from bases, keep solvents away from ignition, never decant into unlabelled bottles. Segregate waste: used oil and coolant to authorised recyclers, e-waste (PCBs, batteries, mercury sensors) never into general bins, oily rags in covered metal bins. Spills are contained with a spill kit or bund, never hosed to the drain.
Worked example
A grinder operator works 4 h at 95 dB(A) and 4 h at 85 dB(A). Allowed time at 95 dB is 4 h; at 85 dB it is 16 h. Dose = 4/4 + 4/16 = 1.25. Because the dose exceeds 1.0, the exposure is over the limit: reduce exposure time, enclose the machine, then issue ear muffs.
Traps
Treating a mask as the primary control; forgetting the 3 dB exchange rule; discarding e-waste as scrap metal; ignoring skin absorption of solvents.