RANT* cigarette smoke

I work in a very small office of 12 people they all know I'm pregnant and my desk is right by the front door yet a good amount of them still stand there and smoke constantly throughout the day. I've closed the door on several occasions but the next time one of them walks out they leave it open...not only is it really bad for the baby but it smells freakin horrible. I've tried switching desks but no one wants to be by the door (I wonder why🤔) also if I'm standing outside at the end of the day waiting on my ride I walk to the other side of the parking lot so I don't have to smell it and a few will follow me just to chat...I get they are young and most don't have kids or have never been pregnant but after explaining to them I can't be around it I shouldn't have to continue to bring it up ugh one more week and I'm out of there