Detecting the presence of lead in the property is not often a straightforward process. It involves obtaining samples from different areas in the property, and sending these samples for testing and analysis to certified lead-analysis laboratories.
There are three sampling methods commonly used to measure the amount of lead in the property, prior to undertaking lead abatement activities. A lead abatement worker collects the samples following guidelines set forth by the EPA. The soil is the first area where lead is possibly located. Dust and dirt can also carry lead in trace amounts. Finally, exterior and interior lead-based paints are often sources of lead structures constructed prior to 1978.
Dust Wipe Sampling
Dust particles can carry lead amounts as they circulate within the property. Dust wipe sampling is not only capable of pinpointing lead contamination, it is also used in post-lead abatement activities. Dust wipe sampling can confirm if the lead cleanup has been successful in removing lead from the area.
Dust samples can only be collected from hard, smooth and nonporous surfaces. Dust from textured surfaces like rough concrete or brickwork will not guarantee good samples, as well as dust sampled from fibrous surfaces such as carpets and cloth-covered furniture.
To collect dust samples, floors and window sills are often the target location. With the use of plastic gloves, the lead abatement worker marks the sampling location with a masking tape or template. A new pair of clean plastic gloves is then used for the actual wipe. The first wipe is from side to side, making sure the entire target surface is covered. The second wipe is from top to bottom using the cleaner side of the wipe, to maximize dust pick-up.
Gravity sends falling lead particles down to the ground from emission sources like car exhausts, industrial factories, and even peeling lead-based paints. Years of fallout may be stored in the ground soil, particularly near roads or manufacturing areas.
Soil sampling is often not required for compliance to Hazardous Waste regulations, but disturbed soil has to be sampled. If the ground soil is opened up by new construction, or a landscaping activity, or from damage caused by physical load or traffic, the long-held lead particles may be released into the air. Lead will eventually lodge in footwear and clothing and result in lead contamination.
As part of lead abatement pre-testing activities, soil samples are obtained through either a coring or scooping method. A half-inch of soil is collected from the top. This sample can be composited in preparation for chemical analysis in the lab.
Paint Chips Sampling
Paint chips sampling can measure the presence of lead in paint. Paint chips are either collected directly from the sample surface or with the help of a portable XRF device that can scan and measure the lead content in the target surface.
For the first method, the lead abatement professional gathers all paint layers in the target area. In using an XRF device, it should be operated following the EPA guidelines and procedures for XRF sampling. In cases when XRF readings are doubtful, such as in non-intact or damaged surfaces, paint chips collection must be conducted to gain conclusive results.
Lead abatement activities should always start with sample collection from any possible sources of lead contamination. Once done, the lead abatement process can proceed with a more accurate knowledge of the extent of lead contamination. Any lead abatement process should strictly adhere to local and state laws for collection, detection, removal and disposal. The safety of workers, the general public and the surrounding environment is a top priority.