My Mom, who is 89, has had asthma most of her life, is allergic to lots of things including strawberries [not only can't eat them, she breaks out in giant whelps if she touches them!]. She is now in the latter stages of COPD, even though she has never smoked ... she is just allergic to everything and is on oxygen 24/7! Being "non-allergenic" was certainly a plus for Toto ... when we are home, Toto is at my Mom's house every day [we discussed it with her Doctor first] ... Toto climbs all over her, covers her with puppy kisses and licks her to pieces!!
Being around Toto has never affected her at all and surely if there were anything about a yorkie to cause an allergic reaction, my Mom would react!! Toto doesn't spend much time outside so it would be my guess that if someone does have an allergic reaction around a yorkie, it would be something that was picked up on their coat and not the coat itself?