Dust samples are collected by vacuuming a specified area (for example, a bed), for a specified amount of time. The sample is collected on a sampling membrane or collection bag that is attached to the vacuum modified for this purpose. The sample is then sent to a laboratory to identify and quantify the presence of specific allergens. As of the 2006 AHHS, the 90th percentile of cockroach allergen was 0.51 Units/g in house dust samples. Targeting reductions in the concentrations at high percentiles (i.e., 90th percentile) is significant from a public health perspective because these exposures represent a worst case scenario for adverse health effects (i.e., asthma and allergies). Also, research has shown that there is an association between the presence of pest problems related to substandard housing making these homes important to target for the mitigation of hazards. Note, also, that a large percentage of AHHS households (86%) had non-detect values, making central measures of little utility.