A HEPA filter is a high quality air filter. HEPA filters are found in air cleansers and purifiers which clean the air by filtering it. HEPA filters are used in industries which require a higher standard ofair quality, such as pharmaceuticals, industrial, aerospace, power generation and electronics. HEPA stands for High Efficiency Particulate Air. HEPA air filters are made from extremely small fibres to filter both microscopic particles and larger ones.