Did you know that your biggest daily exposure to air pollutants comes while driving your car to work?  Until manufacturers start making intelligent vehicles that automatically keep the car cabin’s air clean, the ventilation settings on your car’s dashboard are the best way to protect your health. Fan speed, ventilation mode, and cabin air recirculation options can help protect your respiratory health, but how do you know what the best combinations are?  Cabin air filters were originally designed to remove relatively large particles like pollen and dust and are not very good at filtering out the much smaller, submicrometer particles from vehicle emissions. Gases like carbon dioxide, which is exhaled by passengers; and nitrogen oxide, which infiltrates the cabin from vehicle emissions, aren’t usually filtered and can impair decision making, make people sleepy, or exert adverse health effects. Cabin air quality can be affected by heavy or stop-and-go traffic, ventilation fan speed, vehicle speed, pollutants in outside air, and the number of passengers in the car.  Over the course of a long drive, your car’s cabin can accumulate levels of particulate matter and gases that are very u...