When it comes to air ionizers, there are certain environmental regulations that must be followed in order to ensure the safety of those in the vicinity. Ozone, a lung irritant, is produced both indirectly and directly by ion generators and other electronic air purifiers. The indirect production of ozone is a cause for concern, but the direct and intentional introduction of a lung irritant into indoor air is even more worrying. Despite the claims of some vendors, there is no difference between the ozone present in outdoor smog and the ozone produced by these devices.
Under certain conditions of use, ion generators and other ozone-generating air filters can produce levels of this lung irritant well above levels considered hazardous to human health. A small percentage of air purifiers that claim to have health benefits may be regulated by the FDA as medical devices. The Food and Drug Administration has set a limit of 0.05 parts per million of ozone for medical devices. While ozone can be used to reduce odors and pollutants in unoccupied spaces, such as eliminating smoke odors from homes affected by fires, the levels needed to achieve this are above what is generally considered safe for humans. This fact sheet provides information on air purifiers, including the different technologies used, the selection and the use. Using air purifiers can be an important strategy to help improve indoor air quality (IAQ).
Ozone is a colorless gas that occurs naturally in the Earth's upper atmosphere and protects us from harmful UV rays, although it can also form at ground level. It is known to cause the formation of free radicals in biological systems, which damage tissues. A damage mechanism results from olefin reactions and ozone reacts with electron donors (such as glutathione). Inhaling relatively small amounts of ozone can cause coughing, chest pain, throat irritation, and shortness of breath. Ozone-generating air purifiers are devices that purposely create ozone to clean the air through chemical interactions that alter pollutant compounds; however, this is also the mechanism by which ozone exerts harmful health effects.
In addition, ozone is generally not effective in controlling indoor air pollution at lower concentrations. In other words, if the ozone concentration in the room is high enough to be effective in cleaning the air, it is also high enough to create an inhalation hazard for people in the room. In addition, ozone can even react with chemicals in the air and create harmful by-products. For these reasons, Environmental Health & Safety (EH&S) does not recommend the use of electronic air purifiers or ozone generators under any circumstances. Electronic air purifiers (including ionizers, electrostatic precipitators, hydroxyl generators, and ultraviolet light) use electrical voltage to convert oxygen molecules or other species into their charged ionic components that inactivate air pollutants, in a process called bipolar ionization (BPI).
The ionic components of oxygen are reactive radicals that are capable of removing hydrogen from other molecules. In the case of bipolar ionization, positive and negative ions surround the air particles, destroying the germs and pathogens present, and the added mass helps air particles to fall to the ground and enter the building's air filter. However, BPI can emit ozone and other free radical species as a by-product and may be less effective than other cleaning technologies since charged particles in the air sometimes adhere to room surfaces instead of filtering. Filtering air purifiers pass air through a filter where polluting particles or gases are trapped and return clean air to the room. There is some popular controversy surrounding the extent to which air filters can reduce the presence of larger particles (such as pollen, household dust allergens, mold spores, and animal dander), but most of these large particles settle on home or office surfaces and an air filter cannot remove them unless they are altered and re-suspended in the air. Therefore regular cleaning is the best way to eliminate larger allergens. Air cleaning units have air volume limitations that are identified by a “Clean Air Supply Rate” (CADR).
A CADR is the cubic feet per minute (CFM) of air from which all particles of a given size distribution have been removed. The CADR indicates the volume of filtered air delivered by an air purifier per unit of time with three different scores for smoke, pollen and dust representing different particle sizes. The higher the CADR number for each pollutant, the faster the unit will filter the air for contaminants in a given size range. A carbon filter is most suitable for cleaning gaseous VOCs from the air such as when new furniture is emitting gases. However if you notice an odor in a room contact EH&S first for an evaluation.
The best course of action is to eliminate and control the source of odor and EH&S can perform an evaluation to do so and develop a remediation plan. HEPA filters are better for cleaning particulates from the air with 0.3 micron diameter specification responding to worst case scenario or most penetrating particle size (MPPS). Particles that are larger or smaller are trapped with even greater efficiency. If particle size is used in worst case scenario an efficiency rating is obtained in worst case scenario (i.e., Minimum Efficiency Report Values or MERV indicate ability of filter to capture larger particles between 0.3-10 microns (µm). EH&S recommends HEPA filters for particulate matter and aerosols. All filters need regular replacement as specified by manufacturer in product's user manual.
If filter is dirty and overloaded it won't work well so with proper care and maintenance portable air filter will continue to work properly and filter air. Consider buying replacement filters for air filter. Carbon filters can passively absorb VOCs from air so make sure they remain sealed until they are installed in unit to extend their lifespan. According to EPA there is currently no evidence to suggest that reasonable amount of indoor plants is effective in removing significant amounts of VOCs from indoor environment.