C.M.R. 06, 096, ch. 424, app 096-424-C
Composite Dust Sampling
If composite sampling is used, a minimum of three separate composite dust samples should be collected. A fourth composite sample is needed if wall-to-wall carpets are present. The composite samples should be collected from floor, interior windowsills, and window troughs.
Risk assessors should follow the composite sampling protocol found in Appendix A of this Chapter. The following rules should be observed when conducting composite dust wipe sampling.
Separate composite samples are required from carpeted and hard surfaces (e.g., single composite sample should not be collected from both carpeted and bare floors).
Separate composite samples are required from each different component sampled (e.g., a single composite sample should not be collected from both floors and interior windowsills).
Separate composite samples are required for each dwelling unit.
Floor surface areas sampled in each room should be approximately the same size (1 ft2 or 929 cm2). Window trough and interior windowsill sampling sizes are dependent on window characteristics but should be as similar as possible from room to room (e.g., the surface sampling area should not be skewed so that one room is oversampled).
A new wipe should always be used for each spot sampled.
No more than four different wipes should be inserted into a single container for a composite sample. Acceptable recovery rates (80-130 percent of the "true" value) have been found when no more than four wipes are analyzed as a single sample (Jacobs, 1993©).
While a risk assessor should exercise professional judgement about the number and location of samples, three or four composite dust samples are sufficient for most evaluations in smaller dwelling units.
In an unoccupied dwelling unit or a dwelling unit facing turnover, the areas that are most likely to have lead-contaminated dust should be sampled. In general, floor samples should be collected in the four rooms with the greatest evidence of chipping and peeling paint. In a dwelling unit where children reside, however, areas where young children are most likely to be exposed to lead hazards should be sampled. The recommended subsampling locations for houses with children are the following:
Principal playroom for children (usually the TV room, living room, or dining room).
Kitchen.
Bedroom of the youngest child, who is over 6 months of age (children under 6 months are unlikely to be exposed to dust[1]).
Bedroom of the next oldest child.
The preceding locations for subsamples can be used for both single-family and multifamily dwelling unit risk assessments. However, substitute locations will be necessary in dwelling units where the room designations cannot be determined. For example, in vacant units, the living room should be substituted for the playroom and the smallest bedroom for the youngest child's room.
1https://www.cdc.gov/nceh/lead/prevention/children.htm.
C.M.R. 06, 096, ch. 424, app 096-424-C