With all the attention becoming paid to lead paint these days, researchers within Wisconsin set out recently to shed light on the danger posed by sanding wood ground varnish in older homes. Their work says refinishing older varnished floors created “high” levels of lead dust; however, they also found that the danger posed by this particular lead dust might be lessened by attaching a HEPA-equipped vacuum in order to sanding machines.
The researchers found that sanding old varnished surfaces created lead dust amounts that were higher than federal occupancy standards, or dirt clearance standards. In addition, they determined that certain varnish refinishing operations can produce lead in atmosphere above OSHA standards for workers.
To accomplish the study, researchers frequented 35 homes exactly where Bob Ikens, a report co-author as well as owner of Ikens Hardwood Floors (Madison, Wis.), was refinishing wood flooring; all homeowners volunteered to have their houses tested for the study. Twenty-six of the homes were built before 1930 and nine were built in 1930 or later. Whereas previous studies of wooden floor varnish only looked at lead content in varnishes, for this report the researchers measured for lead before, during as well as after refinishing work had been completed.
Before sanding, researchers took lead level readings from the floor using an X-ray florescence (XRF) analyzer and by scraping the varnish and sending the sample to a laboratory for analysis. While sanding work was being performed, researchers collected air samples within the staff members’ breathing zones to assess lead content in the air; doors and windows were kept closed during sanding. 1 hour after sanding work had been completed, researchers utilized a HUD-approved dust clean sampling method to measure the amount of dust existing. After the work was performed and all examples collected, the areas were cleaned and made secure for re-occupancy.
Researchers looked at samples both exactly where machines (big machine, edger and buffer) were fitted with HEPA-equipped vacuums and exactly where they were not.
Key results include:
The level of guide in a varnish before sanding “significantly correlated” along with airborne lead during sanding.
Machine retrofits resulted in an approximately 54.5 percent reduction in lead within settled dust following sanding was completed.
When machine retrofits were in use, 90 percent of air samples had no noticeable lead.
Pre-refinishing testing found more lead on stairs that on floors, perhaps because steps most often still donned original varnish. As a result, refinishing stairs resulted in higher resolved lead dust levels than refinishing floors.
Hands scraping on stairs produced higher lead-in-air levels than power sanding on flooring. Also, researchers decided that hand-scraping will likely create lead in the air above OSHA-permissible levels when a preliminary lead varnish measurement surpasses 0.18 mg/square-centimeter.
It’s more difficult to get a good vacuum seal on edgers and thus more difficult to control lead in dirt when refinishing stairs than when refinishing floors.
It’s more accurate to measure lead in varnish using a scrape sample instead of relying on a studying from a portable XRF analyzer. This is because the federal standards accustomed to calibrate XRF instruments are not sensitive enough to recognize lead in varnish that could cause hazards.