Thus far the only one that I could find that was 100% non-toxic and made of substances that won’t outgas harmful gases was Heavenly Heat’s Infrared Sauna. It is custom made for MCS (chemically sensitive) patients, so it is not actually listed on the website. You will have to call them and special order it. I think it cost us like $3400.
I think there might be a few other companies that make safe models as well, but I do not know their names. If you google Sherry Rogers Saunas or purchase the book called ‘Detox or Die’ she has a list of good infrared saunas and how to use them.