Based on the data from the breadth of Canada (∼4300 km), one-third of Canadian homes have ventilation rates below the recommended standard of 0.3 air changes per hour and are at risk for moisture problems. For the purposes of this investigation, a literature review was performed on the health risks associated with exposure to living and drying marijuana plants and the fungi associated with large numbers of indoor plantings. Analysis was made of the impact on Canadian homes if used to grow marijuana. These are commonly called “marijuana grow operations” based on measured ventilation rates from homes in Windsor, Ontario and Regina, Saskatchewan (representing diverse climates) and derived moisture loadings from published data. The growing and drying of marijuana plants contributes considerable amounts of water vapour to the indoor environment. Depending on the scale of production, considerable mould damage in the building can result. There are also a number of abiotic hazards resulting from marijuana production including pesticides, carbon monoxide, and products of unvented combustion appliances. Both indirect and direct evidence are described for the health impact of living in these conditions. This has a number of implications in terms of documentation and personal protection for industrial hygienists, home inspectors, and public health officials.

This study examines decontamination processes that were developed on an emergency basis to eliminate Bacillus anthracis spores from deliberately contaminated buildings. The recommended steps include a survey with sampling, the removal of sensitive items, and HEPA vacuuming of all readily available surfaces, followed by biocide treatment and subsequent analyses for viable cells. There are several analytical challenges posed by this approach. These include the ability to discriminate the added strain from naturally occurring resident microbes, determining detection limits for anthrax spores in settled dusts, and detecting viable but nonculturable spores. There are also logistical issues relating to the various skill sets required from investigation to reconstruction. In the present study, a model office was constructed, and a strain of Bacillus pumilus was isolated from the carpet and reintroduced to the office in excess. The abundance of the B. pumilus strain was monitored in settled dust using a strain-specific, quantitative polymerase chain reaction (QPCR)-based detection method following repeated HEPA vacuum cleanings. The QPCR method had a limit of detection corresponding to < or = 10(2) colony forming units per gram of settled dust. QPCR results were compared with measures of dust recoveries and fungal glucan and endotoxin levels in the dust samples. The largest fraction (ca. 81%) of added spores was recovered during the first HEPA cleaning. Subsequent cleanings resulted in incrementally lower recoveries, with removal of 93% of the initial inoculum by the third HEPA vacuuming. HEPA vacuuming prior to removal of items such as office contents and furnishings would result in much less resuspension of dust and limiting the extent of contamination. This approach also ensures that residual contaminants are as low as can be reasonably achieved.