HEPA (High Efficiency Particulate Air) is an air filter efficiency standard – a measure of a filter’s performance. To achieve HEPA performance, filters must meet certain criteria – usually a minimum of 99.95 per cent particle removal at the most penetrating particle size.

The material inside a HEPA filter is usually made of a PTFE or glass-fibre material, arranged as a mat of randomly arranged strands. Depending on the particle size, is it trapped by the HEPA filter in one of three ways:

Impaction: larger particles collide with and are trapped by the net-like structure of the filter fibres

Interception: smaller particles try to follow the air and flow around the filter fibres, getting stuck or snagged on the filter material

Diffusion: particles randomly move when suspended in airflow. Due to Brownian motion, they end up colliding with the fibres and becoming trapped in the filter

Dyson purification technology uses HEPA filtration to ensure particles like bacteria, viruses, pollen and dust are removed from the airflow, projecting cleaner air back into the room. Our HEPA filters are tightly pleated to fit more HEPA filter media into a given space, and which increases the surface area available for capturing pollutants.

To read more about Filtration at Dyson click on our At the core: Filtration link.