Download PDF version (250.1k) Log In or Register to view the full article as a PDF document.

Commonsense Lead Safety

- Continued

Dust-Free Demo

Our heavy weapon for dust control, especially during the demo phase, is a 2,000-cfm negative air machine that keeps the entire work area under negative pressure (Figure 5). This $750 unit (from Abatement Technologies) is a lot pricier than the familiar window-mounted exhaust fan, but it's a much more capable machine.

Image

Image

Image

Figure 5. A 2,000-cfm air handler (above left) keeps the work area under constant negative pressure to prevent dust from escaping. The filtered exhaust air is vented through a 12-inch mylar hose (above right), which is securely taped to a plywood panel mounted in an open window. Besides reducing the lead hazard, the air handler makes demo work much less uncomfortable. The layer of dust on the air handler prefilter (left) represents an hour's worth of tearing down ceiling drywall backed with blown fiberglass. In an unventilated area, most of that would be clogging the air.

Unlike a conventional fan — which blows dust out onto the lawn — the negative air machine forces the intake air through a high-efficiency filtration system that removes virtually all particulates. (The outer prefilter has to be changed at least once a day during demo work, but the more expensive inner filter lasts about a year.) The clean exhaust air is vented through a 12-inch mylar hose mounted in a window

opening. To make sure the negative pressure won't cause backdrafting of the furnace, water heater, or other fuel-burning appliances, we temporarily seal any ductwork with tape. This also keeps dust out of the ductwork and prevents it from spreading throughout the house. Mist and dust. Because it pumps air through the space so quickly, the air handler scrubs most dust out of the air before it has a chance to settle. If we're doing really dusty work, like tearing down old horsehair plaster, we use a hand-pumped garden sprayer to prevent dust from forming in the first place. The trick is to apply a fine mist that dampens the surface thoroughly without leaving it dripping wet (Figure 6). Paint prep is another major source of possibly lead-laden dust, so we have our painting sub wet-sand whenever possible.

Image

Figure 6. Drywall, plaster, and other dusty materials are misted with water before removal to keep airborne dust to a minimum. Material on the floor is misted again before being shoveled into bags for disposal.

These measures work so effectively that you can walk onto a site where demo is going on and not smell any dust. Although our workers occasionally wear nuisance-dust masks, we never need respirators. In fact, our lead-safety trainer tells us that "respirator" is a bad word. If you're producing enough airborne dust to require one, you're doing something wrong. Handling waste. If we're going to discard lengths of standing trim or other bulky material, we place a big sheet of our 6-mil poly in the middle of the floor, pile the scrap on top of it, and mist it. When the pile gets big enough, we roll up the poly and seal it with tape so we can carry it out to the dumpster without sprinkling the floor with paint chips. Smaller pieces of waste, like old plaster, are also misted before they're shoveled into 4-mil contractor bags, sealed with duct tape, and hauled to the dumpster.

Cleanup and Monitoring

Daily cleanup at a lead-safe job site is almost identical to cleanup on any well-managed job site. The big difference is that instead of going over the site with an ordinary shop vac, we use a HEPA (short for "high-efficiency particle arrestance") vac, which is said to filter out 99.97% of all particles down to 0.3 microns. The ten-gallon HEPA vacs we use (from Pullman-Holt) cost us $320 each — pricier than a Craftsman shop vac but manageable for a piece of equipment that will last for several years (Figure 7).

Image

Figure 7. Each job has its own ten-gallon HEPA vac. Unlike that of an ordinary shop vac, its exhaust is almost entirely free of even the tiniest dust particles. Because the used vacuum bags and filters may contain lead dust, they are considered low-level hazardous waste.

During demolition, we may vacuum several times a day, but we always vacuum thoroughly before leaving for the night. That keeps the clients from tracking lead-laden dust into the living space when they look over the site after we've left. Hazardous waste. Even if they contain some lead-based paint, lumber, plaster, and other ordinary demolition waste don't require any special handling by our waste hauler. But the concentrated dust collected by our air handlers and HEPA vacs is considered to be hazardous waste, because it may contain a lot of paint particles. The vacuum bags and used filters are sealed into the same kind of heavy-duty bags we use for construction debris and brought back to our shop, where we put them in a 55-gallon drum with a band seal provided by a local environmental firm. When it gets full, we call the firm, and someone comes to take it away and bring us a new one. Each drum holds the waste from about ten of our projects and costs us about $200 to have emptied. Personal hygiene. We require all of our workers to wash their hands and faces before breaks and meals and at the end of the day. We also provide a dispenser of moist hand wipes that work well and are easy to use. It wasn't easy to get everyone to go along with this at first, but we were persistent. Once it becomes a habit, there's no problem.

Because lead-containing dust can cling to a worker's clothes and affect family members at home, we also require everyone to vacuum their clothing with the HEPA vac at the end of the day. We recommend that workers change into clean clothes before leaving work for the day and bag their work clothes for transportation home. You can't really control behavior off the job, but we also recommend that clothing worn during demolition be washed separately, so that no lead gets transferred to other clothing. Blood testing. All of our employees have their blood lead level tested within 30 days of coming to work for us and every six months after that. Tracking lead levels protects the employee, but it also protects us. If you don't keep records and an employee develops symptoms of lead poisoning, you don't know whether it resulted from working with you, exposure to lead paint at home, stripping paint on a moonlighting job, or a hobby of casting little lead soldiers. Periodic testing takes away some of that uncertainty. It's never happened to us, but if testing showed an increase in an employee's lead level, we could compare it to the records of other workers on the same job. If their levels were unchanged, that would suggest that the first employee's lead exposure was unrelated to work. When our trainer urged us to set up a testing program, we were worried that it would mean a lot of expense and added paperwork, but it doesn't cost us anything. The employees go to their primary care physician, who performs a test to rule out lead poisoning and sends the bill directly to our HMO. The initial test reports go in the employees' personnel files, and 30 days before they're due for another test we remind them to make an appointment with their doctor. If they don't get tested, they can't come to work. Ron Havilandis operations manager at Design Plus Kitchens and Baths in Worcester, Mass.

Sources of Supply

Abatement Technologies

2220 Northmont Parkway

Suite 100

Duluth, GA 30096-5895

800/634-9091

Negative air machines and filters

Pullman-Holt

10702 N. 46th St.

Tampa, FL 33617

800/237-7582

HEPA vacs, bags, and filters