Health & Safety - silicosis

Dr Prassana Krishnan is a specialist in occupational medicine. Here he offers some advice on one of the issues most relevant to stonemasonry - silicosis

Most stone contains silica and cutting, drilling and grinding it can produce Respirable Crystalline Silica (RCS), which can kill. There are around 2,000 stonemasons in the UK who are potentially exposed to RCS, according to the Health and Safety Executive (HSE). Exposure to RCS can result in varying forms of damage to the lungs, one of which is silicosis.

Silicosis is a slowly progressive, irreversible, potentially fatal disease that usually develops many years after initial exposure. Breathlessness is the main symptom and can be accompanied by coughing and wheezing. The highest risk of developing silicosis is from exposure to dry, freshly fractured fine particles of RCS.

Chronic obstructive pulmonary disease (COPD) is an umbrella term that covers emphysema and chronic bronchitis and can be caused by exposure to RCS. The condition usually develops over many years. The symptoms are usually a cough with phlegm and/or wheezing and/or shortness of breath. Smoking can influence the development of silicosis and COPD.

Acute silicosis occurs in people who have very high exposures over a few months or years. It can result in death within months of exposure.

Heavy and prolonged exposure to RCS under the conditions that produce silicosis can also cause lung cancer. Tuberculosis is also associated with silicosis.

Factors affecting exposure to RCS include the type of stone, nature of task, wet or dry working (pre-soaking stones reduces airborne dust levels and water suppression should be provided where possible, although RCS can still be carried in water particles as a fine mist), hand or power tools used (power tools generate much more dust), provision of exhaust ventilation, length of time on task, segregation of work areas, provision and maintenance of respiratory protective equipment (RPE) and good housekeeping.

An HSE review identified a 20% risk of developing silicosis in those exposed to RCS at the workplace exposure limit of 0.1mg/m3 eight hour time waited average (TWA).

The aim of health surveillance is the periodic assessment of exposed workers with a view to protecting and preventing occupationally related diseases. Health surveillance needs to be considered under the Control of Substances Hazardous to Health Regulations (COSHH) 2002 and HSE guidance note G404, Health surveillance for those exposed to respirable crystalline silica.

HSE guidance indicates that "where there is a reasonable likelihood of silicosis developing in the particular conditions of work, health surveillance will be necessary". Other HSE guidance recommends health surveillance when individuals are likely to be exposed to 0.1mg/m3 of RCS for an eight hour TWA.

Setting up a respiratory health surveillance programme should involve an occupational health professional visiting the particular site and assessing the workplace hazards. As part of the surveillance programme all employees potentially exposed to RCS would be seen, respiratory health questionnaires completed and lung function testing (spirometry) performed.

Chest x-rays may be appropriate for individuals with new or worsening respiratory symptoms but are no longer performed routinely as part of respiratory health surveillance. The occupational health professional will issue fitness certificates for each employee, which will form part of their health record and be kept by the employer.

The confidential clinical information obtained from the individual assessments will be kept and maintained by the occupational health provider who performed the assessments.

A responsible person in the company, to whom individuals can report symptoms in between their periodic health checks, needs to be nominated. This person should liaise with the occupational health provider if there are concerns about possible work related ill health.

HSE does not specify the frequency of health checks but it is good practice to keep employees exposed to RCS under annual health surveillance.

Dr Prassana Krishnan is a specialist in occupational medicine accredited with the Faculty of Occupational Medicine of the Royal College of Physicians of London and recently set up his own occupational health business. He has a special interest in the occupational hazards to stonemansons. He was the Lead Physician to the Greater London Authority and British Transport Police. He is currently an occupational health advisor at Ford Motor Company and Coryton Petroplus Oil Refinery. Tel: 02089581185.