Yes, traffic pollution can cause asthma.

More Info: Although most cases of asthma are due to genetic factors, scientists have performed tests that show that children who are exposed to unsafe levels of air pollution while in their younger years have a greater risk of developing asthma and asthma related disorders such as allergies and respiratory problems.

Correlation between Asthma and Pollution

Sciencedaily.com reports that a group of European scientists recently monitored 4,000 children who were born in both high pollution areas and low pollution areas near Stockholm. The group's results show that children who lived in higher pollution areas had about a 60 percent greater risk of having asthma-related symptoms. (see source)

Not all children who grow up in a high traffic area will necessary have asthma. Scientists have simply shown that there is a correlation between people who are exposed to large amounts of pollution and people who have been diagnosed with asthma. Other factors are much more important when diagnosing asthma.

Asthma Typically Related to Genetics

Asthma has typically been shown to be related to genes. Parents who experience asthma symptoms have a good chance that their children will also have the same symptoms. This factor is much greater in determining whether or not a child will have asthma than pollution related issues, but pollution should not be ignored in the diagnosis.

While determining the cause of asthma within a person may be difficult, it is extremely clear that person who have been diagnoses with asthma are much more susceptible to asthmatic attacks if they live in or visit areas of high pollution.