This document provides general guidelines for the design of suitable ventilation systems
for vehicle decks on ro-ro ships, car carriers and car ferries.
Exhaust gas composition
Exhaust gases from motor vehicles contain hazardous substances. Carbon
monoxide (CO) from petrol engines, and nitric oxide (NO) and nitrogen dioxide
(NO2) from diesel engines are the substances whose health hazards are
discussed in this document. These hazardous substances can affect people in many
different ways. Certain substances have a tangible, immediate effect. Others only show
injurious effects after a person has been exposed to them for some time. The effect of a
substance normally depends on how long a person has been exposed to them and the
quantity inhaled.
Carbon monoxide (CO) is a colourless and odourless gas which, to a lesser or greater
extent inhibits the ability of the blood to absorb and transport oxygen. Inhalation of
the gas can cause headaches, dizziness and nausea and in extreme cases causes weakness,
rapid breathing, unconsciousness and death.
Nitric oxide (NO) and nitrogen dioxide (NO2) are compounds of
nitrogen and oxygen, together commonly referred to as oxides of nitrogen or
NOx. NO, a colourless gas is the main oxide of nitrogen formed in the
combustion process. NO itself is not of great concern as regards health effects;
however, a proportion of the NO formed will combine with oxygen to form NO2,
which is of concern from the point of view of human health. NO2 is a brown
gas which has a stinging, suffocating odour. It exerts a detrimental effect on the human
respiratory system. Asthmatics in particular are susceptible to exposure.
Measures
Measures should be considered as follows:
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A reduction in exhaust gas emissions;
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Provision of an adequate ventilation system;
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Limitation of exposure to the gases; and
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Prevention of accumulation of hazardous and flammable gases