Introduction to Health and Safety at Work

Chemical and biological health hazards and control
229
Occupational asthma
has approximately 4 m suffers 
in the UK and it is estimated that 13 m working days are 
lost each year as a result of it. It is mainly caused by 
breathing in respiratory sensitizers, such as wood dusts, 
organic solvents, solder fl ux fumes or animal hair. The 
symptoms are coughing, wheezing, tightness of the chest 
and breathlessness due to a constriction of the airways. 
It can be a mild attack or a serious one that requires 
hospitalization. There is some evidence that stress can 
trigger an attack.
The following common agents of health hazards will 
be described together with the circumstances in which 
they may be found:
Ammonia
is a colourless gas with a distinctive odour 
which, even in small concentrations, causes the eyes to 
smart and run and a tightening of the chest. It is a cor-
rosive substance which can burn the skin, burn and ser-
iously damage the eye, cause soreness and ulceration of 
the throat and severe bronchitis and oedema (excess of 
fl uid) of the lungs. Good eye and respiratory protective 
equipment is essential when maintaining equipment con-
taining ammonia. Any such equipment should be tested 
regularly for leaks and repaired promptly if required. 
Ammonia is also used in the production of fertilizers and 
synthetic fi bres. Most work on ammonia plant should 
require a permit-to-work procedure.
Chlorine
is a greenish, toxic gas with a pungent smell 
which is highly irritant to the respiratory system, produ-
cing severe bronchitis and oedema of the lungs and may 
also cause abdominal pain, nausea and vomiting. It is 
used as a disinfectant for drinking water and swimming 
pool water and in the manufacture of chemicals.
Organic solvents
are used widely in industry as cleans-
ing and degreasing agents. There are two main groups – 
the hydrocarbons (includes the aromatic and aliphatic 
hydrocarbons) and the non-hydrocarbons (such as tolu-
ene, white spirit, trichloroethylene and carbon tetrachlor-
ide). All organic solvents are heavier than air and most 
are sensitizers and irritants. Some are narcotics, while 
others can cause dermatitis and after long exposure 
periods liver and kidney failure. It is very important that 
the hazard data sheet accompanying the particular solv-
ent is read and the recommended personal protective 
equipment is worn at all times.
Solvents are used extensively in a wide variety 
of industries as varnishes, paints, adhesives, glue 
strippers, printing inks and thinners. They are at highest 
risk when used as sprays. One of the most hazardous 
is dichloromethane (DCM) also known as methylene 
chloride. It is used as a paint stripper normally as a gel. 
It can produce narcotic effects and has been classifi ed 
as a category 3 carcinogen in the European Community. 
The minimum personal protective equipment require-
ments are impermeable overalls, apron, footwear, long 
gloves and gauntlet and chemically resistant goggles or 
visor. Respiratory protection equipment is also required 
if it cannot be demonstrated that exposure is below the 
workplace exposure limit (WEL).