American and Chinese researchers have found that shutting down an old, dirty, coal-fired power plant can reduce pollution and significantly improve cognitive development — the ability to think — in young children. VOA's Art Chimes has details on a new study of how children can benefit from cleaner air.

Children's developing nervous systems make them especially sensitive to toxic pollutants.

"This study compares children who were exposed in utero to pollution from coal-fired power plants with children who were not so exposed, and it demonstrates the benefits of closing the plant on children's development measured at age two," said Frederica Perera of Columbia University. She led the research team, which took advantage of a decision by Chinese officials to close down a power plant in the city of Tongliang, in Chongqing Municipality.

"This power plant was shut down because the Chinese government had ordered the closure of old, small, polluting power plants that burned coals, and this one was on the list."

The facility was a major source of chemicals called polycyclic aromatic hydrocarbons (PAHs). Earlier research has identified PAHs as toxic materials that can cause a variety of developmental defects in young children.

To evaluate the impact of PAHs, the researchers compared two groups of children. One group was born in 2002, before the power plant closed; the second group was born in 2005, after it shut down.

Most studies that look at the effects of pollution use indirect measures of how much pollution people are exposed to — such as where they live or where they work. Perera says this study was able to use a more direct measure of exposure.

"We collected umbilical cord blood from babies at birth, and we analyzed the levels of the chemicals, the PAHs, that we were concerned about. And this is a kind of marker or fingerprint of exposure at the individual level."

When the babies were two years old they were evaluated using a standard test of child development, the Gesell Developmental Schedules. And the group born after the coal-burning plant shut down scored higher, particularly in a measure of motor skills.

Perera says she and her university- and hospital-based Chinese colleagues took steps to account for other factors that might explain the change in cognitive development.

"And those did include things like socioeconomic status of the mother and her education, levels of lead; we also measured those in the blood. And second-hand tobacco smoke exposure," she said "We wanted to be sure that what we were seeing was, in effect, attributable to the PAHs and not to some unmeasured factors."

Perera says previous studies demonstrated that the pollutants could be harmful. But the researchers here were able clearly demonstrate the benefits of reducing pollution with compelling before-and-after data.

"This study was unique in that it allowed us to show the benefits of removing such a polluting source and to demonstrate that the children in the second group actually fared better in terms of developmental tests, particularly in the area of motor function," she said.

China has been closing older, dirtier coal-burning power plants. But with oil prices in record territory, coal remains a dominant fuel for generating electricity around the world. The newest, high-tech plants do have pollution controls, but many older ones remain in operation.

As the demand for electricity continues to increase, Dr. Frederica Perera says her research sounds a note of caution ... and, at the same time, demonstrates the benefits of cutting emissions from existing facilities.

"These findings do have relevance for environmental health and energy policy worldwide since these are pollutants that are extremely widespread from fossil fuel burning, particularly from coal, so they are a positive message both for China and the rest of the world."

Frederica Perera's paper appeared this week in Environmental Health Perspectives. The journal is published by the U.S. National Institute of Environmental Health Sciences.