Focusing on Children

Children face special risks from air pollution because their lungs are growing and because they are so active.

Just like the arms and legs, the largest portion of a child’s lungs will grow long after he or she is born. Eighty percent of their tiny air sacs develop after birth. Those sacs, called the alveoli, are where the life-sustaining transfer of oxygen to the blood takes place. The lungs and their alveoli aren’t fully grown until children become adults.68 In addition, the body’s defenses that help adults fight off infections are still developing in young bodies.69 Children have more respiratory infections than adults, which also seems to increase their susceptibility to air pollution. 70

Furthermore, children don’t behave like adults, and their behavior also affects their vulnerability. They are outside for longer periods and are usually more active when outdoors. Consequently, they inhale more polluted outdoor air than adults typically do.71

Air Pollution Increases Risk of Underdeveloped Lungs

Another finding from the Southern California Children’s Health study looked at the long-term effects of particle pollution on teenagers. Tracking 1,759 children between ages 10 and 18, researchers found that those who grew up in more polluted areas face the increased risk of having underdeveloped lungs, which may never recover to their full capacity. The average drop in lung function was 20 percent below what was expected for the child’s age, similar to the impact of growing up in a home with parents who smoked.72

Community health studies are pointing to less obvious, but serious effects from year-round exposure to ozone, especially for children. Scientists followed 500 Yale University students and determined that living just four years in a region with high levels of ozone and related co-pollutants was associated with diminished lung function and frequent reports of respiratory symptoms.73 A much larger study of 3,300 school children in Southern California found reduced lung function in girls with asthma and boys who spent more time outdoors in areas with high levels of ozone.74

Cleaning Up Pollution Can Reduce Risk to Children

There is also real-world evidence that reducing air pollution can help protect children.

In Switzerland, particle pollution dropped during a period in the 1990s. Researchers there tracked 9,000 children over a nine-year period, following their respiratory symptoms. After taking other factors such as family characteristics and indoor air pollution into account, the researchers noted that during the years with less pollution, the children had fewer episodes of chronic cough, bronchitis, common cold, and conjunctivitis symptoms.75


68. Dietert RR, Etzel RA, Chen D, et al. Workshop to Identify Critical Windows of Exposure for Children’s Health: immune and respiratory systems workgroup summary. Environ Health Perspect. 2000; 108 (supp 3); 483-490.

69. World Health Organization: The Effects of Air Pollution on Children’s Health and Development: a review of the evidence E86575. 2005.  Available at .

70. WHO, 2005.

71. American Academy of Pediatrics Committee on Environmental Health, Ambient Air Pollution: health hazards to children. Pediatrics. 2004; 114: 1699-1707. Statement was reaffirmed in 2010. 

72. Gauderman WJ, Avol E, Gilliland F, Vora H, Thomas D, Berhane K, McConnell R, Kuenzli N, Lurmann F, Rappaport E, Margolis H, Bates D, Peters J. The effect of air pollution on lung development from 10 to 18 years of age.  N Engl J Med. 2004; 351:1057-1067.

73. Galizia A, Kinney PL. Year-round Residence in Areas of High Ozone: association with respiratory health in a nationwide sample of nonsmoking young adults. Environ Health Perspect. 1999; 107:675-679.

74. Peters JM, Avol E, Gauderman WJ, Linn WS, Navidi W, London SJ, Margolis H, Rappaport E, Vora H, Gong H, Thomas DC. A Study of Twelve Southern California Communities with Differing Levels and Types of Air Pollution. II. Effects on Pulmonary Function. Am J Respir Crit Care Med. 1999; 159:768-775.

75. Bayer-Oglesby L, Grize L, Gassner M, Takken-Sahli K, Sennhauser FH, Neu U, Schindler C, Braun-Fahrländer C. Decline of Ambient Air Pollution Levels and Improved Respiratory Health in Swiss Children. Environ Health Perspect. 2005; 113:1632-1637.