It turns out that air pollution may have a higher cost than anyone thought. Scientists have found that premature births are linked to air pollution and could be costing as much as $4.33 billion in the United States each year.

In this latest study, the researchers looked at information collected by the Environmental Protection Agency, the Centers for Disease Control and Prevention and the Institute of Medicine. Using this data, the researchers then calculated the average air pollution exposure per year and the number of premature births per county. After doing this, the researchers then calculated long-term health implications of premature birth. These implications include early death, decreased IQ, work absences due to hospitalizations and overall poor health.

"Air pollution comes with a tremendous cost, not only in terms of human life, but also in terms of the associated economic burden to society," said Leonardo Trasande, lead study investigator and professor at NYU Langone. "It is also important to note that this burden is preventable, and can be reduced by limiting emissions from automobiles and coal-fired power plants."

But how expensive is air pollution in terms of premature births? According to the new study, the national percentage of premature births in the U.S. has declined from a peak of 12.8 percent in 2006 to 11.4 percent in 2013. However, these numbers still remain above those that are found in other developed countries.

The current decline currently won't meet the goal of 8.1 percent by 2020. This goal was set by the March of Dimes but may be unrealistic considering the amount of air pollution still present in the United States.

One of the most interesting findings of the new study is that the number of premature births that were linked to air pollution was the highest in urban communities. This is particularly true in southern California and the eastern United States. The peak numbers were found in the Ohio River Valley.

The findings reveal a bit more about the dangers of air pollution. Not only that, but scientists can see how much this will decline over time, which may help show what needs to be done in order to meet goals.

The findings are published in the March 2016 journal Environmental Health Perspectives.