Exposure to diesel exhaust is part of our everyday lives. We encounter diesel-powered vehicles, and the air pollution they create, each day. This occurs in our neighborhoods where diesel-powered vehicles make deliveries or pick up trash, or when we drive behind them during our daily rounds to the store or travel on a highway. Most often, Americans are exposed to diesel pollution on their way to and from work or school, whether commuting via a car, riding on diesel buses and trains, or on foot or bike near a busy thoroughfare.