Childhood asthma is a common condition. According to the American Lung Association, approximately 6.8 million children under the age of eighteen in the United States had asthma in 2006. The children most greatly affected are children between the ages of five and seventeen. Asthma is one of the leading causes of absenteeism from school.

African American children have a higher incident rate than Caucasians. Asthma in African American children is also more likely to have devastating effects. According to information gathered in 1993 comparing asthma in African American children and Caucasian Americans, very young African American children are six times more likely to die from asthma. Boys were also more likely to die from asthma than girls.

Children who live in the suburbs and rural areas are less likely to have asthma than children who live in urban areas. Prolonged exposure to air pollution is thought to be the risk factor responsible for this discrepancy in incidence rates of children in urban areas versus rural areas. Asthma is the leading reason for hospitalizations of children under fifteen in New York City.

However, the urban and rural effects can be different in different countries. In England, the highest incidence rates of childhood asthma are outside the major cities. A proposed reason for this is an elevated level of seasonal allergies and hay fever affecting children in rural areas.

The International Study of Asthma and Allergies in Childhood (ISAAC) collected information on the incidence rates of asthma for different countries. The countries with the highest rates of childhood asthma are the UK, Australia, New Zealand, and Ireland ranging from thirty-six percent in the UK to twenty-eight percent in Ireland. The incidence rate in the United States is twenty-four percent.

Tree-lined streets have been associated with less risk of asthma. Trees seem to decrease the risk of asthma among young children in urban areas. The average amount of trees along New York City streets is 613 trees per kilometer. There is an average of nine percent of children diagnosed with asthma. In areas of New York City that have significantly more trees per kilometer, the rate of asthma has been found to be at least one quarter less than average.

In some cases of childhood asthma, the symptoms are ignored or not recognized by parents, teachers, or physicians. This can prolong the time it takes for a child to be properly diagnosed with asthma. A toddler or young child may stop and grab their chest while playing or running. A young child may not be able to describe how they feel. Children with asthma may say that their chest hurts or their chest feels funny. A child with asthma may often cough during the night.