Ventilation plays a crucial role in maintaining a clean indoor environment. However, ventilation systems can also be major sources of airborne pollutants as a result of inadequate system design, distribution, cross-contamination, etc. Thus, air filtration technology plays a key role in protecting human health by removing indoor air pollutions, while also providing an alternative solution for reducing energy usage, operating costs and thus delivering a way to achieve sustainability.

The main pollutants in the air can be divided into three categories: suspended particles, volatile organic pollutants and microorganisms. In terms of suspended particles, the main purification technologies are filtration, water washing purification, electrostatic precipitation and anion technology. Filtration is currently the most widely used purification technique of particulate matters.

The most effective and commonly used purification method for harmful gases is adsorption. Because of its simplicity, effectiveness and low cost, activated carbon is a widely used adsorption material.

In addition, photocatalytic and plasma cleaning technologies are also effective for the purification of volatile organic pollutants. For the elimination of microorganisms, the most efficient method is ultraviolet (UV) light, followed by photocatalytic and plasma purification. Filters are more effective in the case of bacteria with larger diameter, while they are not suitable for eliminating virus.