The Blueair 402 air purifier is specifically recommended for those who suffer from allergies and other respiratory ailments. This powerful air purifier uses a HEPA silent filtration system for general indoor air pollution control. There are also choices of filters to use particularly for those who are sensitive to smoke and other chemical fumes. This air purifier could effectively serve the air purifying needs of a room 365 square feet big. It has a durable steel housing in a contemporary Swedish design that is easy to maintain. It operates quietly and is energy efficient. This air purifier is also environmentally sound as it uses non-toxic components to purify the air. It combines the ioniser-electrostatic technology with filter technology in order to clean indoor air.

The HEPA silent technology used by the Blueair 402 air purifier is highly efficient. It effectively captures 99.97% of airborne particles up to .1 micron in size. This includes most allergy-provoking pollens and grains as well as dust mites, mold spores, and pet dander. This air purifier uses a two-stage filtration method that puts together an ionizing chamber and a filtration media. The air purifier draws the particles in an enclosed chamber wherein a charged ions attach themselves to the airborne particles. These charged particles allow the air pollutants to cling to the filter media easily. As the charge dissipates over time, this air purifier continuously charges incoming particles to keep the filtration system working constantly.

The filters used in the Blueair 402 air purifier do not contain any harmful components. They are made of ultra-thin non-toxic polypropylene fibers that effectively trap minute airborne particles as they pass through their pleats. These filters do not shed and disintegrate while in use. It does not release any fumes or harmful residue into the air even when it has been rendered ineffective due to soiling. It is actually naturally resistant to bacterial or viral contamination. There are replacement filters specifically designed for this air purifier to ensure optimal air purification for years. Even the discarded filters are environmentally friendly as they are decomposed and converted into carbon dioxide and water. Changing the air purifier filters is recommended every six months. There is an optional SmokeStop filter that could be used for those who are irritated by smoke, gas, odor, and chemical fumes.

This Blueair air purifier operates on less than 20 watts of power consumption on low to about 80 watts of power on high. This energy efficiency is brought about by the way the HEPA silent filtration system works. The combination of two filtration systems make the entire system work smarter instead of harder. The air purifier effectively moves the air through the ionizing chamber and filter media that are not too dense so as to hamper air flow and to make the fans work harder. As the air to be purified as well as the purified air moves freely, the unit's fan does not have to work as hard. Its structural design allows for clean purified air to be gently diffused into the room instead of in gusts of drafty air. The SurroundAir system that this Blueair air purifier is equipped with makes this possible. This air purifier comes in a box-type design measuring 23 inches by 20 inches by 11 inches.