Air Pollution :: Adverse effects of air pollution on births in Los Angeles County

Women who lived in regions with high carbon monoxide or fine-particle levels — pollution caused mainly by vehicle traffic — were approximately 10 to 25 percent more likely to have a preterm baby than women who lived in less polluted areas.

This was especially true for women who breathed polluted air during the first trimester or during the last months and weeks of pregnancy.

IMPACT: Air pollution in Los Angeles County remains a major public health problem that affects everybody, particularly pregnant women. This study provides further facts to policymakers to weigh the costs and benefits of reducing air pollution, both in terms of dollars and human health.

AUTHORS: Dr. Beate Ritz, professor of epidemiology at the UCLA School of Public Health; Michelle Wilhelm; Katherine J. Hoggatt; and Jo Kay C. Ghosh.

JOURNAL: The study appears in the American Journal of Epidemiology, online at

BACKGROUND: The first large-scale air pollution study of its kind, this study collected detailed information on more than 2,500 women who gave birth in 2003. Through personal interviews, researchers were able to determine the risks due to air pollution separate from other risk factors, such as smoking, exposure to secondhand smoke and alcohol use. This work follows two earlier studies that only used information from birth certificates to link air pollution to low birth weight and preterm birth. This latest research factored out other possible explanations, such as smoking, and included specific information on where women spend their time–outdoors, at home, in the car, at work, etc.–which would affect how much polluted air they breathe.

FUNDING: Funding from the National Institute of Environmental Health Sciences, and partial funding from the Southern California Environmental Health Sciences Center, supported the research.

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