Pregnant and people blowing smoke in my face.

Is there anything I can legally do about people smoking around me at my job? I work the drive thru at fast food and people pull up all the time smoking and blowing smoke in my face against my will and it's obvious I'm pregnant. I would go to my boss or even my district manager about it but even the district manager smokes around me inside the building in the back in the kitchen! I'm at a loss of what to do because I don't want to lose my job!