According to the definition in 40 CFR 745.83:
"HEPA vacuum means a vacuum cleaner which has been designed with a high-efficiency particulate air (HEPA) filter as the last filtration stage. A HEPA filter is a filter that is capable of capturing particles of 0.3 microns with 99.97% efficiency. The vacuum cleaner must be designed so that all the air drawn into the machine is expelled through the HEPA filter with none of the air leaking past it."
Therefore, renovation firms should look for a vacuum cleaner that was designed to be operated with a HEPA filter, rather than a shop vacuum that can be fitted with a HEPA filter in place of the original basic filter. A vacuum retrofitted with a HEPA filter is not necessarily properly sealed or designed so that all of the intake air goes through the HEPA filter. EPA also recommends that renovation firms ask the manufacturer or retailer whether the machine has been tested to ensure that it achieves the high efficiency required of a HEPA filter (capturing 99.97% of 0.3 micron particles).
