carbon monoxide,asbestos,legionella bacteria,hepatitis virus-Nebosh Question and Answers

For EACH of the following agents, outline the principal
health effects AND identify a typical workplace situation
in which a person might be exposed:
(i) carbon monoxide (2)
(ii) asbestos (2)
(iii) legionella bacteria (2)
(iv) hepatitis virus. (2)

Carbon monoxide is a colourless, tasteless and
odourless gas. It causes headaches and breathlessness
and at higher concentrations unconsciousness
and death. The most common occurrence of carbon
monoxide is in exhaust gas from a vehicle engine.
Working in a vehicle repair garage without proper
ventilation to exhaust gases would expose a person
to carbon monoxide fumes.
(ii) Asbestos produces fine fibres which can become
lodged in the lungs. This can lead to asbestosis
(scaring of the lungs), lung cancer or mesothelioma –
cancer of the lining of the lung. Asbestos can be
found in buildings, in ceiling tiles and as lagging
around heating pipes. When these sites are disturbed,
the asbestos fibres become airborne and
inhalable affecting those engaged in maintenance or
demolition work.
(iii) Legionella is an airborne bacterium and is found in
a variety of warm water sources between 20 and
45ÂșC. It produces a form of pneumonia caused by
the bacteria penetrating the alveoli in the lungs.
The disease is known as Legionnaires’ disease
and has symptoms similar to infl uenza. The three
most common systems at risk from the bacteria are
water systems that incorporate a cooling tower, air
conditioning units, and showers. People working
on these systems or working in the area of infected
systems are at risk, particularly if they are over
45 years of age and it affects men more than
(iv) Hepatitis is a disease of the liver and can cause
high temperatures, nausea, jaundice and liver
failure. The virus can be transmitted from infected
faeces (Hepatitis A) or by infected blood (Hepatitis
B and C). Hospital workers and fi rst aiders who
come into contact with blood products are at risk of

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