Asthma and automobile emissions are closely related. This was experimentally proven by the significantly reduced number of asthmatic individuals who consulted a physician, were admitted to a hospital or had to be taken into intensive care on a day which had a noticeably lower traffic level than usual.

The greater the amount of emissions from an automobile, the bigger a threat it is toward asthma-prone people. It goes without saying that in larger vehicles cause much more pollution in general, having more powerful engines and using greater amounts of fuel. But what is even more surprising is that many small cars also cause a great deal of pollution, due to inefficient fuel processing systems.

Automobile emissions contain many types of noxious vapours and particles, many of which serve as allergens to asthma-prone individuals, causing them to undergo asthmatic seizures upon contact. Although the allergen sensitivities of people vary widely from person to person, car exhaust fumes contain enough different types of contaminants to infect entire demographics. Research has shown that prolonged exposure to automobile emissions in urban environments may even cause long-term damage to be done to the lungs.