Understanding the dangers of silica dust

Matthew Judson of JSP considers the precautions that construction workers should take to protect themselves from silica dust

The effects of inhaling dust from silica, a very common mineral that occurs naturally in many materials found or used on construction sites, should never be underestimated, just because they may take many years to manifest themselves. Breathing silica dust can be life-threatening and devastating for construction workers, who are at increased risk of developing silicosis, lung cancer and other serious lung diseases such as chronic obstructive pulmonary disease (COPD) and tuberculosis (TB). Silicosis is incurable, since silica particles lodge in the lung tissue, causing fibrosis (permanent scarring), severe shortness of breath and a chronic cough that may also be accompanied by chest pain, fever and weight loss. Many hundreds of construction workers die each year from exposure to silica dust.

Silica has two forms, crystalline and noncrystalline.

The very fine dust from the crystalline form found in sand, sandstone, quartzite, slate, gravel, clay, granite and other types of rock is the most dangerous to human lungs and is known as respirable crystalline silica (RCS).

Common materials used by construction workers containing silica including bricks, tiles and concrete put them at risk of exposure to RCS when using tools such as drills, grinders, saws, sanders, sand blasters, cutters and concrete mixers, or even brooms and shovels. Workers are especially vulnerable to smaller airborne silica particles, which can be inhaled deep into the lungs where they cause irreparable damage.

So what can be done to protect workers from the potentially damaging effects of silica dust on construction sites? Using less hazardous materials, isolating the activity, ventilating the area where work takes place on silica, removing dust by vacuuming and using local exhaust ventilation systems, and suppressing it by spraying water, are all good options for controlling the dust, but they are not enough on their own and cannot always practically be put in place. Well-fitting, appropriate, comfortable, respiratory protective equipment (RPE) should also be provided and workers trained in its correct use and maintenance to prevent them from breathing the dust that inevitably becomes airborne despite these other measures.

The law Several pieces of legislation are concerned with silica dust. In 2006, RCS was assigned a new maximum exposure limit (MEL) of 0.1 mg/m3, (reduced from 0.3 mg/m3) expressed as an 8-hour time weighted average. Activities which may expose workers to silica are subject to the Control of Substances Hazardous to Health Regulations 2002 (COSHH), which require the health risks from silica to be assessed and then prevented or controlled. Fit testing of tight fitting respiratory protection is also mandated under these Regulations. In the European Union, the selection and use of respiratory protection comes under the 2005 Standard EN 529, which obliges employers to put in place both suitable RPE and training in its correct use, fitting and maintenance.

Fit-testing Providing RPE that does not fit the wearer properly can be more dangerous than them not wearing any protection, since it may give a false sense of security. Since the quality of fit-testing in the past has not been adequate and it has often been carried out incompetently, Fit2Fit (Fit Test Providers Accreditation Scheme) was launched by the BSIF in 2009, focusing on raising the quality of fit-testing in the UK.

In their current 'Clean Air - Take Care' initiative, the HSE and BSIF are advocating fit testing of respirators to overcome their often ineffective use in the workplace.

According to the HSE, there are 12,000 deaths every year from respiratory diseases caused by occupational exposure, including silica. One of the HSE's particular concerns is incompatible PPE and the fit testing of combinations of PPE that are normally worn at the same time, such as disposable masks and safety eyewear, because fit test results may become irrelevant when different eye and respiratory PPE are used together.

JSP's innovative FilterSpec, and FilterSpec Pro (a version suitable for power tooling incorporating goggles), combine independent eye and respiratory protection to work in harmony with maximum effectiveness in one integrated, compatible unit that helps to address the challenge of fit and satisfy the HSE's concerns over the quality of the fit. The combined PPE solution solves many of the problems, with high quality P3 level filters, face fit compliance, fog free vision and a comfort that will encourage responsible use.

Using sensible precautions will help ensure that silica dust does not become the new asbestos in 20 years' time.