Last reviewed 12 December 2014

The air in many workplaces contains hazardous chemical or biological agents in the form of dusts, fumes, mists, gases and vapours. When inhaled, many of them (known as irritants) can cause harm to the lungs or other parts of the airways, leading to a range of different inhalation disorders. Lisa Bushby discusses the different types of ill health that may result, preventative action lab managers can take to minimise inhalation risk and the early intervention measures that should be taken to help employees with respiratory problems.

Types of inhalation disorder and occupation risk

There are many types of disorder that can result from inhalation of hazardous substances, some of which, such as asphyxiation or cancer, which can occur through exposure to asbestos, crystalline silica, diesel exhaust particles, etc, can be fatal.

Many substances commonly encountered in labs are known to be irritating to the airways. In particular, highly soluble gases, such as ammonia, chlorine and sulphur dioxide, can have an immediate effect on the upper respiratory tract, while high or prolonged exposure to the substance can also affect the smaller airways, leading to pulmonary oedema, which can be fatal if not treated. Exposure to other gases, such as phosgene, nitric acid and ozone, may have no immediate effect, but can cause a delayed reaction, also leading to pulmonary oedema.

Some irritants can cause permanent lung damage, especially if exposure is very high or occurs frequently. Others can predispose people to conditions such as asthma or chronic obstructive pulmonary disease (COPD) as described below.


Asthma is a chronic condition characterised by periodic inflammation of the bronchi and tightening of the muscles surrounding them. Typical symptoms include wheezing, coughing, tightness in the chest and shortness of breath.

Occupational asthma can be caused by a wide range of agents, known as asthmagens, and include chemicals such as isocyanates and acid anhydrides, and biological materials such as flour dust and some proteins. Individuals with pre-existing asthma may find their condition is aggravated by the substances they are exposed to at work. Hazardous substances that irritate the airways can cause asthma attacks in people with asthma.


Inhalation of irritants can also cause rhinitis, a condition characterised by inflammation of the cells that line the nose. Symptoms include congestion, itching, sneezing and nasal discharge.


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.

While the main cause of COPD is smoking, occupational exposures to certain substances such as cadmium, mineral, organic and silica dusts, have the potential to cause COPD, particularly if exposure is high and over a long period of time.


Pneumoconiosis is a group of lung diseases caused by breathing in insoluble dusts (silicosis results from exposure to silica dusts). Frequently it is a progressive disease, meaning it gets worse even when exposure has stopped. It is marked by an increasing difficulty in breathing, at times leading to death.

Extrinsic allergic alveolitis

Alveolitis is the inflammation of the alveoli by an allergen. Symptoms usually start a few hours after exposure to certain organic materials, commonly fungal spores, with flu-like symptoms. Continued exposure can lead to chronic symptoms and fibrosis of the lungs.

Inhalation fever

Inhalation fever includes polymer fume fever and metal fume fever. Polymer fume fever is caused by breathing in fumes released when polytetrafluoroethylene (PFTE or Teflon) is heated to a high temperature. Metal fume fever is caused by breathing in fumes that contain some types of metal oxides, for example zinc oxide and magnesium oxide, or by breathing in fumes released when heating or melting metals. Symptoms include fever, cough, and pains or tightness in the chest.

Preventive action

To prevent or minimise respiratory problems at work, lab managers should have a respiratory protection management programme in place. The programme should cover the following.

  • Risk assessment. Control of Substances Hazardous to Health (COSHH) regulations require a risk assessment to be completed when working with irritants that includes identifying the hazards, deciding who might be harmed and how, evaluating the risks and deciding on precautions, recording the findings and implementing them, reviewing the assessment and updating it if necessary.

  • Control measures. Wherever possible, the irritating substance should be substituted for a safer one. Where using the irritant cannot be avoided, the work process should be reviewed and redesigned wherever possible so exposure may not occur. If this is not practical, effective control measures for inhalation irritants include local exhaust ventilation and enclosures. Breathing protection should be used as a last resort.

  • Monitoring of exposure. Some inhalation irritants have mandatory workplace exposure limits, in which case it will be necessary to measure airborne concentration levels to ensure the limits are not exceeded. This issue will be discussed further in a future article.

  • Health surveillance. This is mandatory where work with specified solvents, fumes, dusts, biological agents and other substances hazardous to health is carried out. It is done to help identify where more control measures are required or to identify early signs of work-related ill-health among those who are exposed to hazardous agents.

  • Instruction and training. There is a duty to provide those working with hazardous substances with suitable and sufficient information and training on the possible risks to health and the precautions they should take when working with such substances. It should include what symptoms to look out for and how to report symptoms should they arise.

Early intervention

When a lab manager becomes aware of any respiratory symptoms, identified either through the health surveillance programme or via an individual reporting symptoms to him or her, the lab manager should take immediate action to protect the individual from further exposure while the cause of the symptoms is investigated and identified.

Meanwhile, anyone identified with work-related ill health should be referred for diagnosis and/or treatment via the company medical advisor. The medical advisor should be made aware of details pertaining to the individual’s work and the type of substance they have been exposed to.

Where indicators of ill health are found, control measures should be improved. The Health and Safety Executive (HSE) advises that the following be (re)considered along with results from the subsequent health surveillance.

  • The type and duration of work the employee has been carrying out.

  • That all risks in the work activity have been assessed.

  • The most effective and reliable controls are being used.

  • That all routes of exposure have been considered.

  • That sufficient training, both for the job and in the use of equipment used to control the risk has been provided.

  • That control measures are maintained/checked to ensure they remain effective.

  • That any necessary personal or respiratory protective equipment is provided and used correctly. Also that it is being maintained.

  • Non-work related activities that could have caused ill health.

It may be the case that restrictions on the types of substance the individual can be exposed to become necessary to avoid further ill health. This may require adapting the workplace or giving the individual an alternative set of duties.

It may also be necessary to inform the HSE or the local authority of the incidence of ill health under the Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 2013.