A reader asks:

 What is the relationship, if any, between negative air ions and ozone?


There is always some ozonization when negative ions are produced. Depending on the design of an ionizer, the level may be appreciable or negligible. The ionizers that have undergone controlled clinical trials for seasonal and non-seasonal depression produce negligible ozone levels (well below safety cutoffs) that dissipate in the immediate area of the ionizer electrodes. All that said, however, one sometimes reads claims for a specific therapeutic-psychoactive benefit of high levels of ozone. Such claims are unsubstantiated in the scientific literature, and such treatment should be avoided.