Childhood Asthma


Childhood Asthma and Tobacco Smoke

Childhood Asthma and Diesel Exhaust

Asthma: An Introduction


Asthma is a chronic inflammatory disease that is characterized by hyper responsive bronchial smooth muscle, leading to episodic reversible bronchoconstriction triggered by various stimuli. During an asthma attack, several things occur:

  • tightening of the airways that run from the nasal cavity down to the lungs
  • delicate cellular linings (mucosa) of these airways become irritated and inflamed, and as a result the air tubes become swollen
  • mucus production increases, which clogs up the air tubes

Symptoms of an asthma attack, which may last for hours and at times even days, include:

  • wheezing
  • shortness of breath
  • chest tightness
  • coughing

The development of asthma is associated with a complex combination of genetic, allergenic, environmental, psychosocial and socioeconomic factors likely acting in concert with one another. While the ontogeny of asthma is still fairly poorly understood; there is a better understanding of the agents that contribute to its exacerbation.

Asthma symptoms can be triggered by a variety of agents, which can be broken down into two large categories: allergens and irritants.

  • Allergens include mold, pollen, dust mites, cockroach droppings and pet dander.
  • Irritants include environmental tobacco smoke, air pollution, chemicals, and cold air.
    o Indoor exposures include dust mites, cockroach droppings, animal dander, mold and tobacco smoke
    o Outdoor exposures include pollen and air pollution. Specifically, automotive exhaust -- the oxides of nitrogen, ozone, sulfur dioxide, sulfuric acid, fine particulates and carbon monoxide, as well as ambient air pollution -- particulate matter and ozone.

For the purposes of this website, we will be focusing on Environmental Tobacco Smoke (ETS) as an indoor pollutant and irritant.

Overview of Childhood Asthma

Asthma is one of the most common chronic childhood diseases, affecting nearly 5 million children under the age of 18 in the U.S. Consider the scope of this large public health problem:

  • Asthma is the leading cause of school absenteeism due to chronic illness, with 14 million school days missed annually
  • Asthma is the third-ranking cause of hospitalizations in children under age 15
  • One out of every six pediatric emergency room visits is attributable to asthma
  • Between 1980 and 1994, the prevalence of asthma in children age 5-14 years of age increased 74%

Children are especially vulnerable to respiratory hazards for several reasons:

  • children’s airways are narrower than adults
  • children breathe more air per pound of body weight than adults, and thus breathe more pollutants
  • children often spend more time engaged in vigorous outdoor activities
  • children have little control over their indoor environments, thus may be exposed to high doses of ETS

The Role of Environmental Tobacco Smoke in Childhood Asthma

  • The EPA estimates that between 200,000 and 1,000,000 children’s asthmatic conditions are worsened by exposure to environmental tobacco smoke (ETS) each year.
  • ETS is a risk factor for the development of new cases of asthma in previously asymptomatic children.
  • Approximately 43% of children aged 2 months to 11 years live in a home with at least one smoker
  • This is a significant Public Health Issue!

The Role of Diesel Exhaust in Childhood Asthma

  • Because the recent worldwide increase in the number of children with asthma has been linked to environmental factors, including air pollution, the contribution of air pollution from transportation, and specifically diesel exhaust, in the development of pediatric asthma is highlighted in the linked pages.