Respirable Crystalline Silica

Respirable crystalline silica (RCS) is a serious problem in some industries, particularly the construction industry. The cancer burden study of the number of deaths from lung cancer associated with exposure to RCS shows there are about 600 deaths per year, with about 500 of these deaths occurring from exposure to silica dust in the construction sector.

What is silica & how does respirable crystalline silica arise?

Silica is a natural substance found in most rocks, sand and clay and products made from these materials, such as bricks and concrete. In the workplace (including construction sites) these materials create dust when they are cut, drill, sanded, polished, etc. Preparation of concrete floors, such as through bead blasting or shot blasting may lead to substantial quantities of airborne respirable crystalline silica. Some of this dust may be fine enough to reach deep inside the lung, this is known as respirable crystalline silica (RCS) and can cause harm to health. Significant exposure to respirable crystalline silica can cause silicosis and lung cancer.

Exposure levels for respirable crystalline silica

Respirable crystalline silica has a workplace exposure limit (WEL), which contains exposure below a set limit, preventing excessive exposure.

The WEL for RCS is 0.1 mg per cubic metre, expressed as an 8-hour time-weighted average (TWA).

How to control exposure to respirable crystalline silica

The starting point for controlling worker exposure to respirable crystalline silica is a COSHH Assessment. As a substance hazardous to health,  respirable crystalline silica is covered by the COSHH Regulations.

This section of this article will be expanded.

Ill health arising from exposure to respirable crystalline silica

Exposure to respirable crystalline silica can lead to a range of lung diseases:

• Silicosis: Silicosis makes breathing more difficult and increases the risk of lung infections. Silicosis usually follows exposure to RCS over many years, but extremely high exposures can lead rapidly to ill health. Silicosis causes small hard nodules of scar tissue to develop in the lungs that are seen on a chestX-ray. Silicosis usually takes some years to develop. There is also an acute form of silicosis that occurs at very high exposures. This can start within a short time and can kill within a few months of first exposure.The main symptoms are a cough and difficulty in breathing. Workers with silicosis are at increased risk of tuberculosis and lung cancer and may also develop kidney disease and arthritis and related diseases.

• Chronic obstructive pulmonary disease (COPD): COPD is a group of lung diseases, including bronchitis and emphysema, resulting in severe breathlessness, prolonged coughing and chronic disability. It may be caused by breathing in any fine dusts, including RCS. It can be very disabling and is a leading cause of death. COPD interferes with air movement in and out of the lungs and causes breathlessness, often with a chronic cough and sputum (phlegm). Smoking cigarette can make the situation worse.

• Lung cancer: Heavy and prolonged exposure to RCS can cause lung cancer. When someone already has silicosis, there is an increased risk of lung cancer.

Lancashire boarding school has been fined £100,000 after a stonemason exposed to silica dust

A historic private school in Clitheroe has been fined £100,000 over health and safety failings after one of its stonemasons developed a potentially fatal lung disease. Stonyhurst College has been fined after a stonemason developed an incurable lung disease following work to undertake repairs of the 200-year-old buildings, he was diagnosed with silicosis in 2011 from silica dust found in stones. According to the HSE, he may have been exposed to silica dust more than 80 times the daily limit. The school admitted a Health and Safety breach and said it was “remorseful”.

As its buildings needed repairs for wind and weather proofing, Stonyhurst College had employed the 55-year-old worker from June 1999. According to the HSE, he was diagnosed with silicosis in July 2011,  four months before being made redundant by the school. During that period, a couple of other stonemasons were employed to help build a new four-storey, sixth form building. It is understood that the project required more than 400 tonnes of sandstone and the stonemasons worked with powered hand tools cutting, shaping, chiselling and finishing the sandstone.

The HSE investigation found that Stonyhurst College failed to monitor or reduce the exposure to silica dust, despite sandstone containing between 70% and 90% of those particles. The stonemason with silicosis has suffered severe and irreversible health effects as a result of his exposure. He has a reduced lung function, suffers from breathlessness and can no longer continue with his profession.

Stonyhurst College was fined £100,000 and ordered to pay over £31,500 in costs.

After the trial, HSE Inspector Mike Mullen said:

There was no attempt by the college to assess and manage its workers’ exposure despite having their attention drawn to the risks by its own health and safety consultant in 2008.

A worker who was previously very active now struggles to play outside with his grandchildren, and will suffer breathing difficulties for the rest of his life.

 Academic dust-up: Academics have called on the Regulators to tighten the workplace safeguards against harmful silica dust.

According to a new study from the University of Stirling, hundreds of thousands of workers are put at risk and 1,000 could die every year due to exposure to harmful workplace silica dust.  According to Profs Rory O’Neill and Andrew Watterson of the University of Stirling’s Occupational and Environmental Health and Safety Research Group (OEHSRG), crystalline silica is second only to asbestos as a cause of occupational cancer deaths.

The HSE, however, have said tighter limits are not practical. Currently, a workplace exposure limit of 0.1 milligrams per cubic metre is set in the UK under health and safety law.
The same limit is set in the US, but the American regulator OSHA has argued in favour of cutting it by half, as it is based on research dating back as far as 1968. The OEHSRG academics want the HSE to follow suit and tighten standards, but the British regulator is opposed to the move due to technological limitations in monitoring silica levels that precisely.
Prof O’Neill said:

“Modern science can obtain and analyse dust on Mars. “If HSE’s science can’t obtain and analyse adequately one of the most commonly encountered and deadly workplace dust exposures here on Earth, who on Earth they are protecting?”

Prof Watterson added: “OSHA says a tighter standard is perfectly possible, can be monitored in the workplace and would save hundreds of lives and billions of dollars each year. Canadian provinces already monitor and enforce a tighter standard still.”

A spokeswoman for the Health and Safety Executive said the body focused on ensuring the correct controls were in place in workplaces. “When these are in place silica dust is usually reduced to significantly below the exposure limit,” she said. “The advice HSE has received indicates that it is not practical or achievable to consistently and reliably measure real workplace samples of respirable crystalline silica to significantly lower levels. “This is because the technical samplers currently used suffer from interference and poor precision at these low measurement masses.  “Measurement below the current workplace exposure limit would require complex sampling and analysis processes which have not been validated.”