Not sure if it was a TL margin comment or TLed mangaka/artist margin note on p6 -
worth noting that Negative Ions are not pseudoscience, there is a well documented biochemical effect e.g. from rainstorms, waterfalls, etc, as published in officially recognised scientific and medical journals - however it is true that there are countless products on the market which claim to produce them even if they do not do so with any significant area-of-effect -
and as healing as the sight of yuri may be to us, it is most likely not as a result of negative ions.