Effluvium is a smelly gas, vapor, or an exhalation. You wouldn't want to breathe in the effluvium from a cargo ship or you might become ill. Stick to sailing.
Not a particularly common word these days, effluvium dates back to the 1600's, meaning "a flowing out of air." Since the effluvium seeping out of the tire factory's chimney was invisible, park officials took months to realize fumes were killing hundreds of birds. The Romans were the first to invent a sewage system, thereby diverting effluvium into the drains and out of the city. Thank you, Romans.