Car exhaust can contain particulates, especially if the vehicle is an older car or runs on diesel. Scientists are concerned that the particulates carry toxic chemicals, such as nitrous oxide and carbon monoxide, deep into our lungs where they can make us ill.
The US EPA reports (2024) that a typical passenger vehicle emits about 4.6 metric tons of carbon dioxide per year. CO2 is a greenhouse gas. Although vehicles have become more fuel efficient, we are driving larger vehicles (SUVs) and over longer distances.