When someone smokes outside comes back in and smells like it and others can smell it is it harmful like smoking and secondhand smoking?

To babies: To adults, the smell won't cause problems like second hand smoke exposure. It may aggravate allergies or runny nose symptoms. To babies, holding them up against tobacco smoke-infused clothing has been shows to increase respiratory problems.

Yes: Studies have found that 3rd hand smoke, what you are referring to, can be almost as dangerous as smoking in the house with someone.