To do this, just maintain a steady foot angle. When you re driving in summer, close the windows and turn on the fresh air vents. At speeds over 40mph, the drag caused by open windows eats up more gas than a working air conditioner. Shift a manual transmission into the highest gear as soon as possible to use the engine most efficiently. Perform regular maintenance.
Levels are highest in urban areas just after morning and afternoon rush hours.
Large-scale burning of coal, oil and gasoline have overloaded the air with CO 2 . In the presence of sunlight, these compounds form ground-level ozone, the primary component of smog. Children, the elderly, people with respiratory ailments and healthy people exercising outdoors may have difficulty breathing when ozone levels are high. Burning any fuel gas in a car, diesel in a truck, leaves in a pile, or garbage in a barrel - releases sooty particles. Some of the particles are so small that they are invisible to the naked eye.