BCD 2018

154 C AT H E D R A L COMMU N C I AT I O N S C E L E B R AT I N G T W E N T Y F I V E Y E A R S O F T H E B U I L D I N G CO N S E R VAT I O N D I R E C TO R Y 1 9 9 3 – 2 0 1 8 Built before 1992? Paint or Varnish Is encapsulation or overpainting possible? No Yes RISK MANAGEMENT PLAN Coating in good condition? Accessible to children? Yes No No Do not disturb Yes Yes Consider risk assessing: • Lead • Toxic metals and metalloids • Asbestos • Silica • Organic components • Allergens and carcinogens No Is item removal possible? Remove item: • Minimise dust generation during removal Yes No Select lowest risk paint or varnish stripping method possible Non-specialist options Replace item: • Consider specialist waste disposal Strip off-site: • Treat stripped item as hazardous until surface- sealed Full CLAW and COSHH risk assessments for all persons affected (direct and indirect): • Medical surveillance and air testing • Stringent controls, containment and decontamination • Local isolation and extraction with PPE and RPE • Industrial HEPA vacuuming and wet cleaning PAINT TOXICITY and RISK HESAAN SHERIDAN A SMALL BUT vocal contingent in the UK is trying to persuade architects and contractors to treat lead in paint as asbestos, encouraged perhaps by a flourishing US lead abatement and mitigation industry. This lobby is assisted by a lack of independent expertise and by insufficiently robust support from the government on the subject. Although it is true that lead paint is a hazard in old buildings that all designers and contractors should be aware of, demonising lead while ignoring the other heavy metals found in paint is simply not a good risk assessment model. Conservationists must also be mindful of the possible conflict between health risks and the preservation of significant historic features. This article aims to set the record straight by outlining the scientific evidence for concern, and advocates the use of evidence-based risk assessments. UNDERSTANDING THE RISKS Paint or varnish that is in good condition or buried under newer non-lead coatings is unlikely to be hazardous provided it remains encapsulated and undisturbed. However, any redecoration, refurbishment or alteration work represents a potential risk of exposure or environmental contamination. An awareness and thorough understanding of the risks by all those involved is the key to their management. Lead compounds used in paint include: • white pigments and fillers: basic forms of lead carbonate, sulphate, silicates and ‘leaded zinc oxide’ (zinc oxide and basic lead sulphate) • lead tetroxide (‘red lead’) and other coloured anti-corrosive metal primer pigments including calcium plumbate, lead chromate and lead silicochromate • lead monoxide (‘litharge’) and/ or fine metallic lead • lead chrome greens and yellows (lead chromate with/without Prussian blue pigment) • drying agents such as lead naphthenates, acetates, and octenates (which speed up film-formation by catalysing the polymerisation of the binder). The quantity of lead and other paint toxins present in a building is related to its age and the accumulation of multiple coats of paint. The Public Health England National Poisons Information Service reports that ‘despite the toxicity of lead being well known, lead exposure remains a cause of morbidity not only in industry but also to members of the public, particularly to children’, with paint-stripping identified as the most common source for both occupational and non-occupational exposure (see Further Information: Brackenridge). Within the scope of The Housing Act 2004 , the UK Housing Health and Safety Rating System Operating Guidance classifies lead poisoning as a ‘Class 2 harm’ (out of 7, where 1 is highest). Immediate symptoms of workers who stripped paint in old buildings have been documented as fatigue, malaise, loss of appetite, nausea/vomiting, abdominal pain, constipation, headaches, dizziness, mental impairment, joint and muscle pain, weakness of hands and pricking or tingling sensations. Para-occupational lead exposure has been documented where contractors take lead dust home, exposing their own children. The ‘harm’ resulting from lower-level lead exposure may not cause visible symptoms. The human body is particularly bad at removing lead, so it bioaccumulates within bone and dentine throughout our lifetime. There is also evidence that lead within bone is re-released into the blood during pregnancy, at times of stress or poor nutrition, or as we age. Growing research over the past 20 years has indicated subclinical effects in cognition and higher systolic blood pressure in adults and IQ reduction and behavioural problems in children under four Consider risk assessing: • Silica • Organic components • Allergens and carcinogens • Asbestos (pre-1999) • Toxic metals and metalloids (pre-2007) Encapsulate or encase under: • Dry-lining • Over-plaster (with bonding agent) • Other encasement Options for preparation for over-painting: • Wet down and remove loose paint flakes • Light wet sanding • Liquid de-glosser • Specialist sealants, fillers and primers Specialist options: • Laser • Cryogenic • Poulticing • Wet blasting • Dry blasting with efficient vacuum extraction Safest: • Infra-red or heat gun stripping at low temperature • Non-corrosive stripper gel, paste or poultice Moderately safe: • Corrosive or high VOC chemical stripper, paste or poultice • Wet sanding • Sanding with power tools with effective on tool and local extraction Unsafe: • Dry sanding by hand • Dry sanding with power tools using passive dust bags or without on-tool extraction • Gas blow torch or heat gun at high temperature • Train and inform workers • Good hygiene with no hand-to-mouth • No dry sweeping or dust generation • Risk assess inhalation, ingestion, skin absorption • PPE (nitrile gloves, goggles, overalls, face-fitted FFP3 respiratory protection) • Decontaminate work areas and clothing