The state Health Department is conducting another study on the respiratory health of people living near western North Dakota's lignite-fueled power plants.

A 2001 study found small but consistent differences in respiratory problems between children who live in "coal country" and their counterparts in the eastern part of the state.

State Health Officer Terry Dwelle said the results showed a "small but significant" difference.

"We, as the Health Department, need to determine whether or not that difference is real, then try to figure out why," Dwelle said.

Wayne Fisher with the Dakota Resource Council, a conservation group, said enough time was spent on the first study and subsequent reviews of the findings.

"It just seems like respiratory (dysfunction) is a major problem in this state, whether the state realizes it or not," Fisher said.

The first phase of the follow-up study, already under way, will gather more information about the occurrence of asthma in the state.

Officials also plan to create a surveillance system for chronic diseases and increase the number of air monitoring stations around North Dakota.

David Glatt, the department's environmental health chief, said officials want to install several new monitors, mostly in the west and central parts of the state, where power plant emissions are heaviest.

Most existing air-quality monitors are concentrated around areas considered the most sensitive to air pollution, such as Theodore Roosevelt National Park and the Lostwood National Wildlife Refuge, near Stanley.

Glatt said those monitors routinely show little or no air pollution from power plants. The results are part of an ongoing air-quality dispute between state health officials and the Environmental Protection Agency, which contends that industrial pollution is violating federal rules in western North Dakota.

Dwelle said the state will analyze the study's health and air-quality data before deciding if any action is needed to protect public health.

"If there is a real difference, then we would need to determine how we would proceed," he said.

Jeffrey Verhey, a pulmonary specialist and chief of the medical staff at Trinity Hospital in Minot, said the Health Department should move the study along quickly.

"It doesn't surprise me that there's an increase in asthma around those coal plants. We know that the more industrial the country, the more prevalent the asthma is," he said.

"If kids are at risk, we want to do things that we can to decrease their risk," Verhey said.

Rafael Ocejo, a pediatrician at Bismarck's Medcenter One, said he is seeing an increase in young asthma patients.

Ocejo said the study is an important tool in working with the lignite industry to ensure that public health is protected.