High Efficiency Particulate Air, or HEPA, represents very high standards by which air filtration is measured and the most sophisticated, modern, and high-tech vacuum systems employ filters based on this standard.
According to specifications in the United States, a filter must trap at least 99.97% of all particles that are 0.3 microns or larger in diameter. The filter must always retain a high level of airflow as not to reduce suction.
One thing is certain: regulations on exposure to dust particles will continue to be more stringent in coming years. Be prepared by choosing a dust extraction system based on the HEPA standard.