The ammonia vapors will build up and possibly keep the bear from disturbing the trash. It is important to remember that bears are very opportunistic feeders and have keen memories of food sources. If a bear has found a meal of garbage, pet food or bird feed, it will more likely return to the site to feed again. A bear that associates food with people or residences will eventually lose its natural fear of man. This may lead to a bear needing to be relocated or even destroyed.
Most bears are easily frightened into leaving.
Never approach the animal. Observe it only from a distance. Make your presence known through clapping, talking, singing or making other sounds. Make sure the bear has an escape route. These are warning signs that you are too close.