## Occupational hygiene in OHS

Scenario 1 – Biological Monitoring
There is a manufacturing company that produces lead containing products. The process is isolated
such that only a small number of workers are potentially exposed. Two of these workers are males
and one a female of reproductive capacity. In the most recent round of biological monitoring one of
the males (M1) returned a blood lead level of 32 μg/100 mL, the other (M2) a level of 23 μg/100 mL,
and the female (F1) a level of 27 μg/100 mL.
There is a requirement that a worker be removed from lead risk work immediately if the measured
blood lead level is above 2.42 μmol/L for males, and females not of reproductive capacity or if the
blood lead level is above 0.97 μmol/L for females of reproductive capacity. Based on the measured
levels, determine if any of the workers should be removed from performing lead risk work, and then
discuss the requirements for returning to work and the frequency of follow up measurements for all
workers.
Discuss the potential health effects, both acute and chronic, of lead exposure.
Scenario 2 – Personal Sampling
Respirable crystalline silica represents a significant hazard to workers. A mine with significant amounts
of silica present has requested an assessment be done on their workers. This assessment is interested
in determining individual worker exposure. Detail the equipment you would require to collect a
respirable dust sample, via an active means for a worker. This should include all equipment required
to collect and analyse the sample, including pump flow rate.
After 12 hours (a single shift) of sampling, the following masses of respirable dust were collected.
Worker Mass of Dust (µg)
Crusher Operator 2007
Mechanic (1) 529
Mechanic (2) 507
Calculate the average airborne respirable dust concentration for each worker, and compare to the
OES for both respirable dust and crystalline silica (you will need to use the Brief and Scala method
here).
Based on the results of your calculations discuss any potential issue with exposure and any potential
actions which may be required.
Scenario 3 – Noise
A farmer operates an old tractor for the purposes of seeding, on a large farm. The task is likely to take
several days and they do not stick to regular shifts. For the purposes of conducting a noise assessment,
the farmer is fitted with a noise dosimeter one morning before commencing work for the day. After 5
hours and 17 minutes of monitoring, the tractor breaks down and the farmer and work stops until the
tractor can be fixed. The sound level recorded during this time was, LAeq = 87 dB, adjust this value to
an equivalent 8 hour exposure. If the farmer was able to fix the tractor, should he continue working?
A neighbouring farm is also seeding, however are using a different make and model of tractor. A noise
dosimeter is fitted to the farmer, and records the duration of the work for the day. The sound level
recorded was, LAeq,15hr = 83 dB, adjust this to an equivalent 8 hour exposure. Based
on this result what recommendations would you make?
Briefly discuss the limitations associated with using noise dosimetersin these kind of situations, where
it is not possible to observe the worker for the whole job task.
Scenario 4 – Controls
In an underground mine there are a variety of diesel powered vehicles in use. Many of these are old
and have been in use for a considerable length of time. The mine is mechanically ventilated, though is
very hot and humid in a number of locations and has many dead end passages where the air circulation
is poor. There is a concern about worker exposure to diesel particulate matter (DPM) in the mine. A
monitoring study has been conducted and found that a number of workers are being exposed to DPM
concentrations above the TWA limit. Discuss possible control measures, within the context of the
hierarchy of controls. Which of the measures you have discussed, would you recommend be
implemented, and why?