Sitting in traffic has a bigger impact on your health than you may think. All the pollution being generated by neighboring vehicles can actually seep into the buses cabin, creating a concentrated solution of toxic air. As the air recycles through the bus, the toxins can reach levels of up to 10 times those found in normal city air. These pollutants, which are sometimes referred to as particulate matter, are absorbed by the lungs, and can cause problems with the respiratory system, the heart, asthma, lung cancer and various other infections. Exposure to particulate matter pollution can also result in decreased life expectancy. Diesel vehicles are the worst offenders, responsible for 79 percent of vehicle-oriented particulate matter pollution.