Latex paints are more environmentally friendly than oil based paints. With oil based paints there are paint fumes to contend with that can be particularly bothersome on interior painting jobs. There is also a by product of dirty paint thinner that requires a trip to your local toxic waste site. There are other factors as well: Latex primers and finishes have been improving tremendously over the years and are very durable. For instance a latex finish on an exterior painting job will stay elastic for years, where oil based paint dries to form a hard and more brittle film.