Occupational asthma is a highly distressing and potentially life-threatening disease which can seriously damage the health of workers in modern computing and electronic sectors and traditional industries alike.

The Health and Safety Executive in Britain estimates that 138,000 people suffer from work-related asthma each year and that a further 129,000 suffer from other respiratory diseases "caused or made worse by their work".

Employers are legally and morally obliged to identify any respiratory sensitisers in the workplace. A respiratory sensitiser is any substance which when inhaled can cause an irreversible allergy. This sensitisation might take place over a period of up to two years.

It must be stressed that once sensitisation has taken place, the worker will often be permanently damaged and may even lose his or her livelihood. As Dr Muiris Houston, occupational physician and medical journalist told this column: "It's serious. You can be saying to employees `You can't work in this industry for the rest of your life'."

Sensitisers include agents like: isocyanates (used in spray painting and foam manufacture), flour, grain, soldering flux (a health risk in modern high-tech computer and electronic industries), wood dusts, hardening agents, antibiotics, laboratory animals and insects.

Other sensitisers include: glues, resins, paints, cutting oils, cleaning products and disinfectants; organic agents like certain plants, crustaceans, fish and some animal antigens; chemicals like glutaraldehyde, formaldehyde and chlorine; and metal agents like welding fumes, nickel and cobalt.

Some sensitisers will be labelled: "May cause sensitisation by inhalation (R42)."

Apart from the life-crisis occupational asthma can present to the worker, an employer can face litigation as a result.

Figures for the incidence of occupational asthma appear not to be published for Ireland even though Irish cases are collated by SWORD (Surveillance of Work-related and Occupational Respiratory Disease) at the Imperial College School of Medicine in London. However, Dr Houston says that all sources agree occupational asthma is on the increase.

Traditional industries where workers are vulnerable to occupational asthma include: baking, milling, sawmilling and woodworking; while modern industries are chiefly the high-tech computer and electronic sectors.

Other workplace activities where workers are particularly vulnerable to occupational asthma include: vehicle spray painting, chemical processing, foam manufacturing, plastics manufacturing, metal treatment, food processing, grain-handling, laboratory animal work and the curing of epoxy resins.

An employer is legally obliged to identify any workplace sensitisers and to record them on the company Safety Statement. The employer must inform employees about any workplace sensitiser and ensure that they understand the risks these present to their health. Employers must satisfy themselves that each employee has grasped and can put into practice all safeguards or protective measures and they must ensure that these safety procedures are appropriately supervised.

An airborne sensitiser can affect many more people than only those who work directly with it so employers need to determine which employees are potentially exposed to the sensitiser. Employers can manage workplace respiratory sensitisers as follows:

Substitute a safer substance for the sensitiser if possible.

If substitution is not possible, restrict the number of workers exposed to the sensitiser by cordoning off the area where it is used.

Provide exhaust ventilation at the point of work to prevent or reduce sensitisers becoming airborne.

If after these control measures a sensitiser remains a threat to workers' health, provide workers with respiratory protective equipment.

Make sure employees know how to use and that they do actually use safeguards and controls to reduce exposure to sensitisers.

Engage an occupational physician to devise an on-going comprehensive respiratory health surveillance programme for workers. Candidates at pre-employment medicals should fill out a questionnaire on respiratory symptoms and allergies, and undergo pulmonary function tests (PFTs).

Pick up problems at an early stage even before a worker becomes symptomatic by using PFTs as part of a regular respiratory screening programme.

Train workers to appreciate that occupational asthma could end their career and leave them with lifelong respiratory problems.

Make sure employees are trained to report without delay even apparently minor symptoms like runny or itchy eyes and nose to the doctor, manager and safety representative. Symptoms of more developed asthma which should be reported include: shortness of breath, wheezing, a tightened chest and coughing.

Check that workers understand that early diagnosis can prevent occupational asthma from becoming debilitating.

Move any worker to new duties whom the occupational physician believes could have become sensitised to a workplace sensitiser.

Re-examine current control measures and upgrade them to protect other workers and your business.