Introduction to Health and Safety at Work

13.9.3 Substitution
Substitution is the best solution. It is much better to 
replace a dangerous substance with a substance or 
process that totally eliminates the risk. In practice this 
is diffi cult to achieve so it is more likely that the danger-
ous substance will be replaced with one that is less haz-
ardous (e.g. by replacing a low-fl ashpoint solvent with a 
high-fl ashpoint one).
Designing the process so that it is less dangerous is 
an alternative solution. For example, a change could be 
made from a batch production to a continuous production 
process; or the manner or sequence in which the danger-
ous substance is added could be altered. However, care 
must be taken when carrying out these steps to make 
sure that no other new safety or health risks are created 
or increased, as this would outweigh the improvements 
implemented as a result of DSEAR.
The fact is, that where a dangerous substance is 
handled or stored for use as a fuel, there is often no 
scope to eliminate it and very little chance to reduce the 
quantities handled.
Where risk cannot be entirely eliminated, control 
and mitigation measures should be applied. This should 
reduce risk as follows.
13.9.4 Control 
measures
Control measures should be applied in the following 
order of priority:
➤
reduce the amount of dangerous substances to a 
minimum
➤
avoid or minimize releases
➤
control releases at source
➤
prevent the formation of an explosive atmosphere
➤
use a method such as ventilation to collect, contain 
and remove any releases to a safe place
➤
avoid ignition sources
➤
avoid adverse conditions (e.g. exceeding the limits 
of temperature or other control settings) that could 
lead to danger
➤
keep incompatible substances apart.