Running protects the lungs from pollution

When you exercise in polluted air increases the amount of inhaled air pollution. Becomes more dangerous for cyclists and runners who inhale large amounts of air. Breathing through the mouth, bypassing the natural filtering mechanism of the air - the nose.
Based on these arguments, athletes are in danger when trained in polluted air. New research shows conflicting results. 

Air pollution increases inflammatory processes and subjected lung of stress which increases the risk of death. Aerobic exercise reduces inflammatory processes and stress. So a dispute arose whether the benefits of exercise outweigh the risks that bring training in an environment with the air.
Once the tested mice for five weeks, the researchers found that mice that run in polluted air are less damaged by the mice in an environment where the air which does not run. Aerobic exercise reduces inflammatory processes in mice caused by polluted air.

We are not mice, so their results can hardly be true for humans. If you have respiratory or heart problems should check with your doctor when you exercise in an environment with polluted air. For everyone else, training with polluted air is recommended rather than sit back and relax.