A number of studies have found evidence that air pollution may contribute to the problem of preterm births, raising babies' risk of health complications. Now for the first time researchers are putting a price tag on the impact. According to a new report, the economic cost of preterm births linked to air pollution in the United States totals over $4 billion a year.

The study, published in journal Environmental Health Perspectives, estimated that almost 16,000 premature births across the country in 2010 -- about 3 percent of the nationwide total of 475,368 -- were related to exposure to high levels of air pollution. This leads to about $4.33 billion in additional costs, including $760 million spent on prolonged hospital stays and long-term use of medications, as well as $3.57 billion in lost economic productivity due to physical and mental disabilities associated with preterm birth.

"For policy makers, decisions about regulating air pollution come down to a trade off between the cost of preventing air pollution and the health and economic benefits of limiting air pollution sources," study author Dr. Leonardo Trasande, associate professor in the Departments of Pediatrics, Population Health and Environmental Medicine at NYU Langone Medical Center, told CBS News. "Without data documenting the health effects of air pollution on preterm births, there's only one side to that discussion. So what we did was to quantify the disease burden and economic cost associated with preterm birth that could be traced to air pollution."

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Past research has shown exposures to high levels of air pollution increases toxic chemicals in the blood and can weaken the immune system, causing stress to the placenta and leading to preterm birth (defined as birth before 37 weeks of pregnancy). Premature babies face greater risk of health issues including heart and breathing problems, weaker immune systems, anemia, jaundice and other complications. Longterm, while many preemies grow up healthy, they can be more likely face hearing or vision problems or developmental disabilities.

For the study, Trasande and his team examined national data from the Environmental Protection Agency, the Centers for Disease Control and Prevention, and the Institute of Medicine. They calculated average air pollution exposure and the number of premature births at the county level. After analyzing the numbers, they found that 15,808 preterm births could be linked to air pollution.

The researchers then used a number of statistical methods to determine the economic costs associated with direct medical care in the immediate aftermath of preterm birth, health care costs for developmental disabilities in the first few years after preterm birth, and reductions in economic productivity over lifetime due to lower average IQ associated with premature birth.

The study authors emphasize that this burden is preventable and say they plan to share their findings with policymakers in an effort to help shape regulations and laws designed to reduce air pollution and protect public health.

"This really speaks to the need to continue with efforts to reduce air pollution from coal-fired power plants and vehicle exhaust," Trasande said.

Individuals can also take steps to protect themselves by using air filters and closing their windows and limiting time spent outdoors on high air pollution days -- which can be checked on airnow.gov.

The analysis also showed that the number of preterm births linked to air pollution was greatest in urban counties, primarily in Southern California and the eastern U.S., with the highest rate in the Ohio River Valley.

The study authors say they're planning future research examining the role of specific outdoor air pollutants, and whether any stages of pregnancy are more susceptible to their negative effects. They also plan to expand the analysis to a global level.

"These kinds of economic data have been very instrumental in being the foundation for policy change," Trasande said. "Unfortunately, sometimes these economic data are more compelling than the usual stories about individuals being affected."