Transcript Document
Silica Risks from Kerb, Paving and Block Cutting What is the Problem? One of the most abundant materials on earth Found in varying amounts in many materials: • • • • Sandstone (>70%) Sand, gravel, flint (up to 70%) Cement, mortar, concrete (25 to 70%) Brick (up to 30%) What is the Problem? Why is it a Problem? • Particles need to be “respirable” to cause harm • Issue is Respirable Crystalline Silica or RCS • RCS particles can penetrate to deep lung • Usually invisible under normal conditions Why is it a Problem? Why is it a Problem? • • • • • Main concern is SILICOSIS Lung Disease Reduced lung function Can cause death Disease continues to develop when exposure has stopped • Can also cause lung cancer and COPD Why is it a Problem? Statistics are imprecise: • Affects 10 – 20 % of construction workers??? • Over 500 silica related deaths in 2004 – – Over 10 a week • Research suggests silica is the second most important cause of occupational lung cancer after asbestos Why is it a Problem? Industry appreciation of the risk is poor: • People not aware of these health risks • Think that it is ‘just dust’ • Underestimation of exposure levels • Require convincing that control measures work How Much is a Problem? • COSHH sets WEL for RCS at 0.1mg/m3 (8hr TWA) How Much is a Problem? 15 years daily exposure to RCS dust at average airborne concentrations (for an 8-hour shift) of: 0.02 mg.m-3 Risk of developing silicosis within 15 years following cessation of prolonged daily exposure 0.25% 0.04 mg.m-3 0.5% 0.1 mg.m-3 2.5% 0.3 mg.m-3 20% How Much is a Problem? How Much is a Problem? 15 min SLAB CUTTING (40% silica) in open air, no control • Diamond blade = RCS exposure of 1.6 mg/m3 • Resin blade = RCS exposure of 4.8 mg/m3 Control Solutions • Can the risk be eliminated? • Can a ‘dust free’ method of work be used? Control Solutions Water Suppression Control Solutions Water Sources Control Solutions Water Suppression has other advantages: • Extends the life of expensive diamond blades • Helps prevent build up of dust in the machine workings Control Solutions Issues associated with water suppression use: • Marking the cut line • Slurry generation • Wet legs Control Solutions On-Tool LEV is also an option What about RPE Disposable (FFP3) Power Assisted PF = 20 More information • Time to Clear the air – free leaflet http://www.hse.gov.uk/pubns/misc830.pdf • Time to clear the air! Using cut-off saws for cutting kerbs and flag paving – DVD http://www.hse.gov.uk/construction/clearth eair/index.htm