airfiltration

Air filtration is the process of removing particulate matter and, in some cases, gases from indoor air by passing it through a filtration medium. The goal is to improve indoor air quality, protect occupants, and reduce contaminants in occupied spaces and industrial processes.

Filtration works through physical mechanisms such as interception, impaction, diffusion, and electrostatic attraction. Media used include mechanical filters (fibrous and pleated media) that trap particles, high-efficiency filters such as HEPA and ULPA for very small particles, and activated carbon filters that adsorb gases and odors. Some systems combine filtration with other methods, such as disinfection or gas-phase treatment, to address a broader range of contaminants.

Key standards and ratings help specify performance. HEPA filters typically remove at least 99.97% of 0.3-micron particles; ULPA filters offer even higher efficiency, often above 99.999% for smaller particles. In HVAC applications, MERV ratings (1–16) indicate overall particle removal efficiency, with higher numbers providing greater filtration. Standards such as ASHRAE 52.2 and European EN 1822 guide testing and performance.

Applications span residential HVAC, commercial and industrial buildings, healthcare facilities, cleanrooms, laboratories, and automotive cabin air systems. When selecting filtration, factors include the targeted particle sizes, required air flow, pressure drop (which affects energy use), replacement cost, and maintenance schedules.

Limitations include increased system resistance leading to higher energy consumption and the need for regular filter replacement. Proper disposal of used filters and appropriate selection to minimize bypass are important considerations in managing air filtration programs.