City Streets in Summer
More specifically, any foul odor—a public restroom, old squeegees, fish bits or any other nose-wrinkler—primes the subconscious to send you a message: "Protect yourself!" The result of spending time in a stinky space is that we unthinkingly have safer sex, finds a study at the University of New Mexico. Men and women sitting in a room that smelled (they were told a sewage pipe broke) reported significantly greater intentions to use condoms than those in a normal-smelling room. An innate disease-avoidance mechanism kicks in—which (if an off odor doesn't turn us off completely) could lead to fewer STIs and unplanned pregnancies.