My neighbors are making me sick

A lot of the work I do is done at home. I grade papers, write lesson plans, respond to students' e-mails, and complete my own research for my graduate studies. I also have a part-time job working for a website, and I am able to complete this work on my laptop. I have a desk at school, but I'm only on campus three or four days a week and I do my work every day.

The problem is my neighbors' smoking. They have a right to smoke in their own apartments. But I have a right to breathe freely in my apartment. I also should not have health problems because of my neighbors' habits. Every night the people who live next door come home and smoke for hours. How do I know? Because the smell of their smoke seeps into my apartment. I've tried opening my windows to air out the place, but my apartment happens to be on the second floor, directly above the front door. Several people in the building smoke in the doorway, so whenever my window is open the stink of their cigarette smoke comes into my apartment. It's ironic that they smoke outside so that their own apartments won't smell bad, but in the process they make my own apartment reek. I wish I could post a NO SMOKING sign on my door and on my window. I've also thought about pouring a bucket of freezing water over the smokers' heads, but I guess that would be too extreme.

I've tried using scented candles, air purifiers, Febreze, and potpourri to resolve the problem, but nothing really works. It's not like I can knock on my neighbors' door and ask them to stop smoking. I have considered, though, asking the people who smoke outside to at least step away from the doorway so that their smoke doesn't come directly into my apartment. Or would that be rude? I've also been tempted to slip a package of nicotine gum under my neighbors' door, though I guess that would be rude too. But it's often hard to complete my work when I keep coughing and sneezing from all the cigarette smoke. They say if you can't beat them, join 'em. But cigarettes are really expensive, and I'm too broke to smoke.