Bests & Worsts Reviews from Amazon

Air purifiers with ionizers are tested to not exceed 50 ppb of generated ozone, they are not tested to produce 0 ppb. Ozone is unhealthy. In shopping for an air purifier I found various forms of misleading information regarding one stage of filtering called ionizing (plasma, ion). It is true that if you create an intense electrical field you can strip electrons of particles such as dust to make the dust electrically charged and therefore be attracted to an anode plate be collected instead of in the floating in the air. This same process may also kill bacteria and mold. But it is also true that the same mechanism strips electrons off of gasses such as oxygen and nitrogen. When oxygen is affected by the ionizer it becomes ozone. Ozone is a very unstable, highly-reactive, oxidizer. Think of it as a free-radical that wants to bond with something and most likely make something bad or at least unintended. It is toxic. The California Air Resources Board (CARB) limits for ozone emission concentration is 0.050 parts per million or better yet 50 parts per billion. For every billion molecules or air you are not allowed to exceed 50 molecules of ozone. That is a very, very, very small amount. It would seem like the fact that CARB has set this limit then everything should be ok. Well, the irritating ingredient in smog is ozone. On smoggy days ozone levels often exceed 100 ppm. During 2017 in Southern California ozone exceeded 100 ppb for 145 days in a row. Smog related ozone tends to drop every night. But if you are using an ionizer 24/7 and add its ozone output to the background levels of ozone you could create a real health hazard. The NIOSH recommended exposure limit for ozone is 100 ppb. According to NIOSH, Ozone levels of 500 ppb or higher are considered immediately dangerous to life or health. For filtering a mechanical filter is safer – coarse washable pre-filter, heap filter, and activated carbon are all you really need.