During an asthma attack, the patient's airways become irritated, narrowing and constricting, causing difficulty in breathing by restricting airflow.

Why do some people have asthma while others don't? Why is asthma more common in the Western world?

The causes of asthma are complicated.

It is include our genes, the things that we are exposed that may develop into allergies and contributing factors in the environment such as pollution that can determine whether these genes and allergies will cause asthma at some time during our lives.

Although asthma is not contagious and you cannot catch it through contact with another person, you can inherit the asthma tendency from your parents.

If a parent is a smoker then a child is twice as likely to develop asthma than children of non-smoking parents.

Children whose mothers smoked during pregnancy are often born with smaller airways, which can greatly increase the chances of the disease developing.

The "westernised" lifestyle and the environment in developed countries has a lot to do with the chances of whether a person will develop asthma or not.

These factors include pollution, allergies to house dust mites, cats, dogs, and moulds.

Ironically, it seems that childhood infections and exposure to substances from bacteria in a dirty environment, assuming such an environment doesn't kill you, seems to build up a protection against allergies and resistance to asthma that is why richer populations have more allergic disease.

Allergies are the cause of almost all asthma in young people, meaning that the patient has both inherited genes that have a tendency towards asthma and have been exposed to allergy - producing things in their environment. Both the allergies and the genes are the causes for developing asthma, because if either of them were not present then no asthma would develop.

At a Glance Asthma - Causes

 When talking about diseases such as asthma, it is important to distinguish between causes and triggers.

 A cause is something without which the effect of having asthma will not happen. Without a cause a patient would not be asthmatic.

 Common causes of asthma include a family history of asthma, allergies and exposure to certain infections when young.