In September of 1992, the HEPA House Cleaning Project began with 120 families and high expectations. The study was intended to measure the effect of regular and thorough vacuuming with a "High Efficiency Particulate Air" vacuum. The Lead Program hoped that this study might result in a significant decrease in children's blood lead levels and floor dust lead levels. Unfortunately, vacuuming every six weeks did not produce the results hoped for, but many useful insights were gained during the course of the study.

When the study began, names of the participating families were randomly drawn to determine which 60 would form the treatment group (those that would receive the vacuuming once every six weeks during the 10 month period) and which 60 would form the control group (a comparison group that would not receive vacuuming).

The study was completed in June of 1993, with over a thousand dust samples having been collected.

The study found that there is a direct relationship between dust and lead. If the level of dust on a floor is high, the level of lead is also high. This relationship was seen in all of Trail's neighbourhoods.

As expected, each time the floors and carpets were vacuumed, the amount of lead on the carpets decreased. Over the course of the study, the amount of lead on carpets in homes which were HEPA vacuumed dropped, while the control home results did not change. However, the drop was not large enough to cause a measurable difference in blood lead levels between the two groups.

Some items of general interest from the study were that: vacuum cleaner power heads increase cleaning effectiveness, older carpets tend to have higher amounts of lead, removing shoes at the door has a measurable impact on indoor lead levels, and children with pets tend to have higher levels of lead on their hands and carpets.

Children with higher blood leads tended to have more lead dust on the carpets and hands, which indicates that it is important to vacuum carpets regularly and ensure children wash their hands frequently.

After the final vacuuming, 18 of the treatment homes received carpet dust sampling once every seven days for six weeks. The purpose of the additional sampling was to observe how quickly lead re-accumulated on the carpets. Levels were found to decline after the vacuuming and then return to "normal" in a period of 2.5 days to 3 weeks.