Action News vol 3 no 4 Spring 1995.
Clean-up and Clearance Prior to
by Prof. Brian Gulson and Fred Salome
The following is an extract from the Workshop Manual for the Lead Paint Management training programme being offered in 1996 by Macquarie University Graduate School of the Environment in conjunction with CTI Consultants. The authors have granted permission for this extract to be reproduced. This extract covers final clean-up and clearance prior to rehabitation, which is an important subject not covered in the "Lead Alert" The Six Step Guide To Painting Your Home brochure distributed by the Commonwealth EPA.
All lead hazard control activities can produce dangerous quantities of leaded dust. Unless this dust is properly removed, a building will be more hazardous after the work is completed than it was originally. Once deposited, leaded dust is difficult to clean effectively. Whenever possible, ongoing and daily cleaning of leaded dust during lead hazard control projects is recommended. Regular cleaning is also necessary to minimise worker exposures.
Cleaning is the process of removing visible debris and dust particles too small to be seen by the naked eye. Removal of lead-based paint hazards in a dwelling unit will not make the unit safe unless excessive levels of leaded dust are also removed. This is true regardless of whether the dust was present before or generated by the lead hazard control process itself.
Many of the special cleaning methods and procedures required for lead paint management are not standard operating procedure for general building or painting contractors. Therefore, contractors must follow the methods and procedures recommended below, even though some may appear to be redundant and unnecessary. These methods have been shown to be feasible and effective in many situations and skipping steps in the cleaning procedures can be counterproductive.
When cleaning is complete, surface dust sampling should be carried out to verify the dwelling is suitable for occupancy. This is referred to as clearance testing.
Cleaning activity should be scheduled at the end of each workday when all active lead hazard control throughout the dwelling has ceased. Sufficient time must be allowed for a thorough and complete cleaning (usually about 30 minutes to an hour).
Daily cleaning will later help to achieve clearance dust levels by minimising problems that may otherwise occur during final cleaning, and will limit worker exposures.
Daily cleaning should consist of:
The only way that lead hazard control work can proceed safely in occupied dwellings is to ensure that cleaning is completed before residents re-enter the work area. Daily cleaning is especially important when residents are present in the dwelling while work is in progress, or when residents return in the evening after work has been completed for the day.
Neither debris nor plastic sheeting may be left overnight outside the dwelling or in any area where passers-by or children could come into contact with these materials.
Wait for at least one hour after the completion of any work that results in the generation or disturbance of dust before commencing the final clean-up operations.
The following equipment is needed to conduct cleaning:
The first step in cleaning up is to thoroughly vacuum all surfaces using a HEPA vacuum cleaner. HEPA vacuum cleaners differ from conventional vacuum cleaners in that they contain high-efficiency filters that are capable of trapping extremely small, micron-sized particles. These filters can remove particles of 0.3 microns or greater from air at 99.97 percent efficiency or greater.
Vacuuming by conventional machines is unlikely to be effective, because much of the fine dust will be exhausted back into the environment where it can settle on surfaces. A recent Canadian study revealed that fine-dust air levels were exceedingly high when a standard portable vacuum with a new bag was used.
There are a number of manufacturers of HEPA vacuums: HEPA filters are often fitted as optional items on industrial vacuum cleaners. At present, at least one manufacturer in Australia distributes a domestic machine which has HEPA filtration as a standard item. It is Model GM 210 from Nilfisk of Australia Pty Ltd.
Surfaces requiring vacuuming in final cleaning include ceilings, walls, floors, windows, interior and exterior sills, doors, heating, ventilation, air conditioning equipment (heating diffusers, radiators, pipes, vents), fixtures of any kind (light, bathroom, kitchen), built-in cabinets, and appliances.
To aid in dislodging and collecting deep dust and lead from carpets, the HEPA vacuum must be equipped with a beater bar (agitator head) which is fixed to the cleaning head. This bar should be used on all passes on the carpet face during dry vacuuming.
All rooms and surfaces should be included in the HEPA vacuum process, except for those which were found not to have lead-paint hazards and were properly sealed from work areas before the process began.
Vacuuming should begin on the ceilings and end on the floors, sequenced to avoid passing through rooms already cleaned, with the buildings entryway cleaned last.
Verandahs, footpaths, driveways, and other exterior surfaces should be vacuumed if exterior hazard control work was conducted, or if debris was stored or dropped outside.
At the conclusion of the initial HEPA vacuuming, all vacuumed surfaces should be thoroughly and completely washed with a high-phosphate solution or other lead-specific cleaning agent and rinsed.
Several types of detergents have been used to remove leaded dust. Those with a high-phosphate content (containing at least 5 percent trisodium phosphate, also known as TSP) have been found to be the most effective. TSP detergents are thought to work by coating the surface of dusts with phosphate or polyphosphate groups which reduces electrostatic interactions with other surfaces and thereby permits easier removal.
Users of cleaning agents for leaded dust removal should follow manufacturer's instructions for the proper use of a product, especially the recommended dilution ratio. Even diluted, trisodium phosphate is a skin irritant and users should wear waterproof gloves. Eye protection should also be worn, and portable eyewash facilities should be available. Consult manufacturer's directions for the use of other detergents.
Because a detergent may be used to clean leaded dust from a variety of surfaces, several types of application equipment are needed, including cleaning solution spray bottles, wringer buckets, mops, variously sized hand sponges, brushes, and rags. Using the proper equipment on each surface is essential to the quality of the wet-wash process.
As with the vacuuming, wet washing work should proceed from ceilings to floors and be sequenced to avoid passing through rooms already cleaned. To avoid re-contaminating an area by cleaning it with overly dirty water, the cleaning mixture should be changed after its use for each room. As a rule of thumb, 20 litres should be used to clean no more than 100 square metres.
Used cleaning mixture is potentially hazardous waste; consult with your local water and sewage utility for directions on its proper disposal. Wash water should never be poured onto the ground. The wash water is usually filtered and then poured down a toilet, if the local water authority approves.
Final HEPA Vacuum
A final HEPA vacuuming is carried out to remove any remaining particles dislodged but not removed by the wet wash.
Clearance testing determines whether the premises or area is clean enough to be reoccupied after the completion of a lead paint hazard control project. A cleaned area may not be reoccupied until compliance with clearance standards has been established. To prevent delays, final testing and final cleaning activities should be coordinated.
The number of locations at which surface dust is to be sampled will depend on the nature of ambient lead sources (internal and external) and their accessibility especially to children. Lead dust sampling is most important if renovations have been recently carried out, or if deteriorating lead paint is present.
Hard non-absorbent surfaces should be targeted. These typically include windows, floors, shelves and exterior parts of buildings such as window sills, tiled verandahs, and garden furniture. Surfaces exposed to rain or regular use will usually have low dust levels, whereas sheltered surfaces (under eaves, verandahs, window wells, tops of doors or features) may have accumulated fall-out from petrol or other sources giving high lead levels.
Chalking paint surfaces can also be sampled to gauge the likelihood of lead dust being liberated by paint deterioration.
An area is marked out on the surface to be sampled. The area should be at least 250 cm2, preferably 900 cm2 depending on the amount of dust present. Mark out the sample area using masking tape, measure the lengths of the sides of the sample area and calculate the surface area; make a note of this figure.
To prevent contamination, wear disposable gloves and change gloves after each sample. Use commercially available wipes moistened with a non-alcoholic wetting agent such as Diaparene‘ Baby Wash Cloths. Place a wipe flat onto the surface to be sampled and rub in an "S" pattern.
Fold the wipe in half with dust inside and rub at 90o to the first "S". Fold the wipe again with the dust inside and place it in a sterile sample container usually supplied by the analytical lab.
Label the tube with the sample number, location and surface. Carefully document the exact sample location for future reference.
The sample is then sent to an analytical laboratory for determination of the amount of lead by AAS or ICP.
According to the United States Department of Housing and Urban Development (US HUD) Guidelines, the permissible amount of leaded dust remaining on each of the following surfaces following lead hazard work is:
system lead poisoning |
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