The smoke makes me feel so sick, how can I get roommates to understand?

I'm 8 weeks pregnant, I'm surrounded by smoke. 24/7 weed and cigarettes and cigars. I can't escape, and if no one is smoking the house lingers with the smell. I'm sick from the smell all day. My roommates(4 of them) will not leave the house and smoke outside. I have one window that opens in my room and it's open all day. Smoke seeps in through the door and I'm so sick, literally and figuratively of the smell. How can I get it through everyones head that I'm pregnant and can't be around the smell? I have sprays and they're always gone by the end of the month. They make jokes when I'm walking around with something over my nose, I feel I should move out but can't ATM. They have absolutely no respect for anyone(not even themselves), so how can I gain they're understanding?