Crime against tourists is almost always of the petty sort, such as pickpockets in crowded markets or buses - things smart travelers can easily guard themselves against. Some neighborhoods where you should be careful at night are Constitución (around the train station), the eastern border of San Telmo and La Boca (where, outside tourist streets, you should be careful even during the day). Minor nuisances include lack of respect for pedestrians (do not expect cars or buses to stop or even slow down when you're crossing a street), lax pollution controls and cigarette smoke everywhere.