How does a household air filter trap dust particles?

Household air filters trap dust particles through a few primary mechanisms, depending on the type of filter used.

Mechanical Filtration

Many high-efficiency filters, such as HEPA filters, utilize a dense, pleated mat of randomly arranged fiberglass fibers. As a motorized fan forces air through this medium, dust particles are trapped when they adhere to the fibers or become embedded within them. While it is a common misconception that these filters act like simple sieves—catching only particles larger than the holes in the mesh—they actually capture a wide range of sizes. Very small particles, in particular, collide with gas molecules, which slows their passage and increases the likelihood that they will strike and stick to the fibers.1

Electrostatic Filtration

Some air filtration systems leverage static electricity to improve capture efficiency. In these units, airborne particles are given an electric charge as they enter the system. The filter layers are designed with an opposite charge, creating an attractive force that pulls the particles out of the airstream and traps them on the filter surface. This principle is also used in industrial electrostatic precipitators, where particles are attracted to oppositely charged collection plates.23