While some students and professors have valid concerns about the presence of smokers on campuses around the country, demanding that people extinguish their cigarettes everywhere on campus is unreasonable — not to mention unenforceable for an urban school like Boston University.

The restrictions that exist at nearly 100 schools with entire-campus smoking bans turn colleges into arbiters of personal decision, rather than protectors of public health. To think that students who want to avoid a cloud of smoke are inhibited at every square inch of public, outdoor space on a campus is absurd.

Restrictions on smoking around entrance ways and in other crowded public spaces are reasonable, and such limits at BU could help ensure that the courtesy smokers should show others by avoiding poorly ventilated or heavily trafficked areas is codified. By instituting a 10-foot area surrounding all doors from the College of Arts and Sciences to individual brownstones and placing placards around campus to inform students of the expected standard, BU could make sure that students who want to avoid smoke in unavoidable areas, like stoops and porches, can do so.

Prohibiting smoking inside all dormitories, classroom buildings and other indoor areas sufficiently guarantees clean air for nonsmokers, while setting reasonable limits for those who choose to smoke. It protects the rights of the university community to fresh air while not overstepping the role of the university in making students’ decisions regarding completely legal activities. A prohibition on loitering and smoking in the areas around doorways is a reasonable and, importantly, enforceable boundary. Ordinary people who are not affiliated with BU can pass through this area while smoking, but also recognize from a sign what courteous behavior is expected here.