In recent years, air ionizers have become increasingly popular as people look for ways to improve the air quality in their homes. But some critics believe that air ionizers emit dangerous levels of ozone, which can be hazardous to health. Additionally, ionizers are not effective at reducing VOCs (Volatile Organic Compounds) in the air. Research has shown that there is weak evidence that negative air ionization is associated with lower depression scores, particularly at the highest exposure level.
However, there was no constant positive or negative influence of air ionization on anxiety, mood, relaxation, sleep and personal comfort measures. Experts agree that ozone is harmful to health and certain regulatory bodies have taken action in this regard. In fact, air purifiers that generate ozone are banned in some places. These products generate significant amounts of ozone, which can cause long-term damage to olfactory cells and lungs if inhaled.
Even more worryingly, symptoms may disappear after repeated chronic exposure, leaving people unaware of the damage being done to their respiratory systems. Even small amounts of ozone can be harmful. A Canadian study found that measurable bronchial reactivity can occur at ozone concentrations as low as 0.35 parts per million. Ozone can also react to common household cleaners, such as terpenes, which are more commonly known in pine and citrus fragrances, forming formaldehyde - a group 1 human carcinogen. The SARS epidemic fueled the desire for personal ionizers in East Asia, including Japan (where many products have specialized to contain negative ion generators).
While some studies have reported a variety of pulmonary benefits after exposure to negatively charged air ions, and some studies have reported some mildly unfavorable pulmonary responses after exposure to positively charged air ions, overall the literature provides no reliable evidence of the effects of negative or positive air ions on pulmonary, respiratory or metabolic measures. A study on air ionizers in school classrooms reduced particle concentrations and led to some improvements in the respiratory health of children aged 11 to 14. However, it had an adverse effect on heart rate variability (a measure of cardiovascular health), meaning that any benefit to the lungs came at a cost to the heart. The California Air Resources Board has a page listing air filters (many of them with ionizers) that meet their indoor ozone limit of 0.050 parts per million. The market for air purifiers is booming but a new study has found that some air cleaning technologies marketed for COVID-19 may be ineffective and have unintended health consequences. In a study of 46 adults with severe emphysema or fibrosis, or both, 13 patients were exposed to negative air ions for 1 hour and 33 patients were exposed to negative air ions for 3 hours, and there was no significant effect on lung volume measurements. Overall, while there is evidence that negative air ionization may be associated with lower depression scores and improved respiratory health in children, there is no reliable evidence of any major health benefits associated with using an air ionizer. In addition, because ionization doesn't filter particles from the air or kill mold or viruses, these viable particles continue to accumulate in the room. Therefore it is important to be aware of the potential risks associated with using an air ionizer.
