Development of an Environmental Relative Moldiness Index for US Homes

Objective: The objective of this study was to establish a national relative moldiness index for homes in the United States. Methods: As part of the Housing and Urban Development's American Healthy Homes Survey, dust samples were collected by vacuuming 2 m² in the bedrooms plus 2 m² in the living rooms from a nationally representative 1096 homes in the United States using the Mitest sampler. Five milligrams of sieved (300 µm pore, nylon mesh) dust was analyzed by mold-specific quantitative polymerase chain reaction for the 36 indicator species in 1096 samples. Results: On the basis of this standardized national sampling and analysis, an "Environmental Relative Moldiness index" was created with values ranging from about -10 to 20 or above (lowest to highest). Conclusions: The Environmental Relative Moldiness Index scale may be useful for home mold-burden estimates in epidemiological studies.