Air purifiers are an essential tool for improving indoor air quality (IAQ). Ozone is a naturally occurring gas in the Earth's upper atmosphere, but it can also form at ground level and cause damage to tissues. Inhaling ozone can lead to coughing, chest pain, throat irritation, and shortness of breath. Ozone-generating air purifiers create ozone to clean the air, but this is also the mechanism by which ozone exerts harmful health effects.
For this reason, Environmental Health & Safety (EH&S) does not recommend the use of ozone generators. Electronic air purifiers use electrical voltage to convert oxygen molecules or other species into their charged ionic components that inactivate air pollutants. This process is called bipolar ionization (BPI). BPI can emit ozone and other free radical species as a by-product and may be less effective than other cleaning technologies. Filtering air purifiers pass air through a filter, trapping polluting particles or gases and returning clean air to the room. Air cleaning units have air volume limitations that are identified by a “Clean Air Supply Rate” (CADR).
A higher CADR number indicates a faster unit for filtering contaminants in a given size range. Carbon filters are best for cleaning gaseous VOCs from the air, while HEPA filters are better for cleaning particulates from the air. HEPA filters respond to the worst case scenario or most penetrating particle size (MPPS).EH&S recommends HEPA filters for particulate matter and aerosols. All filters need regular replacement as specified by the manufacturer in the product's user manual.
Carbon filters should remain sealed until they are installed in the unit to extend their lifespan. Indoor plants are not effective in removing significant amounts of indoor air pollutants, so regular cleaning is the best way to eliminate larger allergens. Ions are produced by an electronic device as air passes through and molecules split. Forced air systems with two-speed or variable-speed fans can operate at a lower fan speed when a lower rate of air cleaning or fresh air ventilation is needed. To take full advantage of the benefits, a HEPA filter must be combined with ionization to remove odors and VOCs from the air.
If a space is larger than 90 m2, several air purifiers should be used depending on the total area of the space. Doing this will obstruct airflow and reduce exposure to air from your convection air purifier.
