This is a total myth as everyone knows how dangerous second-hand smoke is to pregnant women as well as other adults and children. If you are exposed to second-hand smoke during pregnancy, both you and your baby are put at risk. Some of the health conditions associated with being exposed to second-hand smoke are a miscarriage, low birth weight, early birth, learning or behavioral deficiencies in your child, and Sudden Infant Death Syndrome (SIDS). Third-hand smoke is the residue left behind by cigarettes on furniture, in rugs, in paint, etc. Third-hand smoke can stick around for months or years. If a place smells like smoke, even if no one is currently smoking, it is a safe bet there is tobacco residue there. You can read more about second and third hand smoke and pregnancy here: https://americanpregnancy.org/pregnancy-complications/second-hand-smoke-and-pregnancy/
All Surrogacy agreements have a non-smoking clause or at the very least a clause that states the surrogate will follow OBGYN’s orders/guidelines and in those orders is to not expose yourself to smoke or pollution of any kind (within reason) besides cigarette and marijuana smoke there are the chemical fumes from mani and pedicures, some hair dyes, and gasoline fumes to name a few sources.
Some women who want to become surrogates have partners or husbands who smoke. Even if they state they will only smoke outside the home, there is still that chance of 3rd hand smoke in the car and on clothing. The best bet is to have everyone in the home to be non-smokers.