Inhalation disorders are dysfunctions
associated with the breathing in of a substance which can be in the
form of a dust, fume, mist, gas or vapour.
Types of inhalation problems:
definitions and symptoms
Chronic obstructive pulmonary
The air in many workplaces contains hazardous substances in the
form of dusts, fumes, mists, gases and vapours. These substances
can be chemical or biological agents, for example, animal
allergens, fungal spores and bacteria. When workers inhale them,
they can harm the lungs and other parts of the airways. In some
cases, hazardous agents move through the lungs to other parts of
the body, harming other organs.
The respiratory system is divided into three areas:
- the upper airways or respiratory tract, which includes the
mouth, nose, sinuses, pharynx and larynx
- the middle airways, including the trachea and bronchi
- the lower airways, including the bronchioles and
Many people have a genetic tendency towards allergic disease.
After they’ve been exposed to chemical or biological agents,
they’re more likely to develop conditions such as rhinitis and
asthma. Many of the diseases described in this section of the
website can occur without occupational exposure.
Types of inhalation problem: definitions and symptoms
- chronic obstructive pulmonary disease (COPD)
- extrinsic allergic alveolitis
- inhalation fever
- cancer (including mesothelioma)
Irritation of the airways can be produced by a
number of dusts, gases, vapours and fumes. These gases can also
irritate the eyes. The part of the respiratory tract affected by a
gas or fume is determined by its solubility. Highly soluble gases,
such as ammonia, have immediate effects on the upper respiratory
tract (and eyes). Usually, if someone is exposed to an irritant
they’ll move away from the source, limiting any damage. Very high
exposure or continual exposure to a dangerous substance can lead to
the smaller airways being affected, leading to inflammation and
oedema in the bronchiolar and alveolar walls (pulmonary oedema),
which can be fatal if not treated. Other soluble gases include
chlorine and sulphur dioxide. Relatively insoluble gases, such as
phosgene, might have no immediate effect, but can cause pulmonary
oedema some hours after exposure. Nitric acid, fluorine and ozone
can also cause a delayed reaction.
Some irritants can also cause permanent lung damage, especially if
exposure is very high or occurs frequently. Others can predispose
people to conditions such as chronic obstructive pulmonary disease
(COPD) or pneumonia.
Asthma is the most commonly reported
occupational respiratory disease in Britain. It’s a chronic
condition characterised by periodic inflammation of the bronchi and
tightening of the muscles surrounding them. It occurs in response
to one or more triggers. Typical symptoms include wheezing,
coughing, tightness in the chest and shortness of breath.
Asthma caused by work can be divided into two categories:
occupational asthma and asthma that is aggravated by work.
Occupational asthma can be caused by a wide range of agents,
known as ‘asthmagens’. These include chemicals such as isocyanates
and acid anhydrides, as well as biological material such as flour
dust and some proteins and laboratory animal allergens such as the
skin, urine, fur or saliva of rats and mice. Typically, the
condition of employees who suffer from occupational asthma worsens
during the working week, and improves at the weekend or while away
Asthma which is aggravated by work is pre-existing asthma that’s
exacerbated by something in the workplace. It is sometimes referred
to as work-related asthma.
Hazardous substances that irritate the airways can cause asthma
attacks in people with occupational asthma, as well as those with
To find out more about the causes of asthma, check out the HSE’s
list of workers commonly
affected and the substances which
cause occupational asthma and asthmagen
Rhinitis is inflammation of the cells that line
the nose. Symptoms include congestion, itching, sneezing and nasal
discharge. Asthma and rhinitis often coexist. Associated with
asthma and rhinitis is conjunctivitis, which is characterised by
itchy, watery and inflamed eyes. It’s important that employers and
employees take rhinitis seriously, as it can develop into
Chronic obstructive pulmonary disease (COPD) is
a lung disease in which the airways become narrower over time,
making it difficult to breathe. Other symptoms include coughing,
wheezing and an increase in the production of phlegm. Chronic
bronchitis and emphysema are types of COPD.
The main cause of COPD is smoking, although exposure to
different types of hazardous substance can cause or contribute to
Byssinosis is caused by breathing in
unprocessed cotton dust. It’s now very rare in the UK and other
developed countries. Symptoms include shortness of breath, coughing
and obstruction of the airways. Symptoms typically occur on the
first day of the working week and subside on later days. If an
employee is exposed to cotton dust for a long time, their symptoms
can become chronic.
Pneumoconiosis covers a group of lung diseases
that are caused by breathing in insoluble dusts, mostly mineral
dusts, that the lungs can’t get rid of. The most common diseases in
this group are silicosis, coal miners’ pneumoconiosis and
- Silicosis is caused by inhaling crystalline
silica (quartz) dust. It commonly occurs in people who work in
quarrying, mining and sand blasting, as well as those who work in
the pottery industry and iron and steel foundries. It’s a
‘progressive’ disease – it gets worse even after exposure has
stopped – and is marked by an increasing difficulty in breathing,
at times leading to death.
- Coal miners’ pneumoconiosis is caused by
inhaling coal dust. It is characterised by a slight cough and the
production of black sputum. In some people, it leads to progressive
massive fibrosis, disability and death. With the decline of the
mining industry in the UK, this disease has become less
- Asbestosis is characterised by scarring or
fibrosis of the lungs following long-term asbestos exposure.
Symptoms include shortness of breath, a non-productive cough and
‘finger clubbing’ – a deformity of the fingers and fingernails.
It’s typically progressive, invariably resulting in death. It’s
also associated with mesothelioma and cancer of the bronchus (see
Extrinsic allergic alveolitis is caused by
breathing in certain organic materials, commonly fungal spores.
Alveolitis is the inflammation of the alveoli by an allergen.
Symptoms usually start a few hours after exposure, with flu-like
symptoms: fever, fatigue and shivering. As the disease progresses,
the sufferer experiences breathlessness and develops a cough.
Continued exposure can lead to chronic symptoms and fibrosis of the
lungs. ‘Farmer’s lung’ is a type of extrinsic allergic alveolitis
and is caused by inhaling dust or spores from mouldy hay, grain or
Inhalation fever includes polymer fume fever
and metal fume fever. Polymer fume fever is caused by breathing in
fume that’s released when polytetrafluoroethylene is heated to a
high temperature. The symptoms resemble flu and include fever,
cough, and pains or tightness in the chest.
Metal fume fever is caused by breathing in fume that contains
some types of metal oxides, for example, zinc oxide and magnesium
oxide, or by breathing in fume that’s released when heating or
melting metals. The sufferer experiences flu-like symptoms,
including fever, cough, and pains or tightness in the chest. It’s
typically found in welders and foundry workers.
Cancer can occur anywhere in the respiratory
tract, from the nose to the lungs. Although, the biggest cause of
lung and other respiratory cancers is smoking, hazardous substances
found in some workplaces can also cause cancer, for example,
crystalline silica, diesel exhaust particles and radon gas.
Exposure to asbestos can cause lung cancer or mesothelioma –
cancer of the lining of the lung or bowel. Relatively low level or
short term exposure to asbestos can cause both types of cancer.
People typically exposed to asbestos, and therefore at higher risk,
are plumbers, carpenters and other construction and building
maintenance workers. There’s usually a long delay between first
exposure and the onset of symptoms (up to 50 years). If workers are
exposed to asbestos and they also smoke, they have a much higher
risk of developing lung cancer than those who are exposed to
asbestos only, or who only smoke. For more information, visit the
HSE’s web pages on asbestos-related
lung cancer and mesothelioma.
People who are exposed to polycyclic aromatic hydrocarbons, such
as coke workers, face a higher risk of lung cancer. Other lung
carcinogens include arsenic, cadmium, chromium and nickel.
People who work with wood or leather and who are exposed to
dusty conditions are at an increased risk of cancer of the nasal
You can get information on the impact of cancers of the lung,
mesothelioma and the nose/sinuses in the HSE’s Burden of
occupational cancer in Great Britain.
Infections caused by agents in
the workplace account for a very small proportion of more serious
work-related inhalation problems. In 2006, 51 cases of occupational
respiratory infectious diseases were reported to THOR.
Occupationally related infections include anthrax, psittacosis,
Legionnaires’ disease and
influenza (bird flu). You can find out more in the HSE’s report
on Infections at work:
controlling the risks.
Asphyxiation is a hazard for people who work in
confined spaces, such as welders. When oxygen is displaced by a gas
or vapour, it can be difficult and even impossible for people to
breathe. Asphyxiants can be divided into simple and chemical
asphyxiants. Simple asphyxiants are inert gases or vapours such as
nitrogen, carbon dioxide, hydrogen and methane, which displace
oxygen from the air when they’re in high concentrations. Chemical
asphyxiants include carbon monoxide, which combines with
haemoglobin to prevent the delivery of oxygen to the cells, and
hydrogen cyanide and hydrogen sulphide, which disrupt respiration
at a cellular level.
Approximately 12,000 people die each year
due to occupational respiratory disease and about two-thirds of
these due to asbestos-related diseases or COPD.
According to the Labour
Force Survey, an estimated 35,000 workers who had worked
in the year 2011/12 suffered breathing or lung problems which they
believed were caused or made worse by their work. This
estimate includes respiratory diseases other than occupational
asthma. The survey also concludes that 667,000 working days were
lost due to breathing or lung problems in the same year, resulting
in an average of 19.3 working days lost per case.
The HSE-financed THOR Scheme estimates the
incidence rate of work-related respiratory disease to
be approximately 240 new cases per million workers per year
during the period 2009-11. This is equivalent to about 7,000
new diagnosis of respiratory disease each year. However, the THOR
scheme is subject to under reporting and other evidence suggests
that the true incidence rate may be much higher.
The HSE has web pages on the latest available statistics
pneumoconiosis and silicosis and
other respiratory diseases such as allergic rhinitis,
byssinosis, farmer’s lung etc. The HSE also has statistics on
lung cancer and mesothelioma.
In the UK, between 9 and 15 per cent of asthma in adults is due
to occupational factors. Approximately 15 per cent of COPD cases
are work-related, and there are around 4,000 deaths a year from
COPD caused by past exposure to dusts, chemicals or fumes.
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Inhalation disorders | Non work-related conditions