Hi yoyo,
In that article, I recommend that any memory foam or polyurethane foam be certified for offgassing or toxicity by a reputable testing organization, such as Oeko-Tex or CertiPur.
There are different testing organizations with differing criteria for different types of foams, some of the more popular ones I describe in post #2 here, which is linked to frequently on the site and easily found. Additionally, I speak about the CertiPur process in post #12 here and how it evolved and some of the other testing organizations, such as Oeko-Tex, LGA, Eco-Institut and Greenguard.
I don’t favor one group over the other and it would be up to you to determine the level of testing, certification, and what is “safe enough” for your own personal use. Post #2 talks a bit more about this and chemicals in a mattress.
Phoenix