Feeling under the weather? That may truly be the case.

A physician and meteorologist duo from Canada have designed an early-warning system that takes forecasting to a new level by using scientific data to track how weather changes affect our health. MediClim.com ( www.mediclim.com) is a free health-weather forecasting service that sends a local warning e-mail 24 hours prior to specific weather conditions that are likely to negatively impact your health.

At first glimpse, I was skeptical. Doesn’t someone with known allergies realize winds blowing around pollen may trigger an immune reaction? In the summer, The News-Sentinel publishes daily ozone levels to warn people with sensitive respiratory systems.

But what if, prior to any symptoms felt in the body, we could have advance warning of negative triggers to our cardiovascular system or neuromuscular system or to alert us of pending blood-sugar problems?

That is the early-warning system, a medical-climate index, that Dr. John Bart and biometerologist Denis Bourque, both of Toronto, have developed.

“The system is based on research done in Europe over the past 60 years,” said Bart, a practicing physician who has been researching weather’s effects on various health conditions for 25 years.

The MediClim.com index encompasses 14 different possible weather states or combinations, such as air temperature and pressure, wind direction and rotation, and humidity.

“Each state has attached to it the ability to change one’s health conditions,” Bart said, noting at least a week’s weather measurement must be considered to ensure reliability. At day eight, “You have a picture of what the air mass moving across the country is like.”

Integrating data from German researchers, Bart and Bourque have developed a weather-health algorithm that Bart says “is reliable and repeatable,” with about 90 percent accuracy in forecasting health outcomes based on weather patterns.

So what are the practical applications? They are noteworthy from a public-health and personal-health perspective, Bart says.

For example, in research commissioned by the Canadian government, he and Bourque studied 440,000 patient visits to emergency rooms in four Toronto hospitals between June 2000 and December 2004. By comparing the medical reason for the ER visits with weather conditions the previous seven days, with 95 percent to 99 percent accuracy they could conclude which weather conditions correlated with specific health problems, such as migraines or asthma attacks, that led to the ER visit.

Bart said if just one ER visit per patient in a single year had been avoided, it would have saved millions of dollars. In fact, the amount of money saved, he said, would have equaled what the Canadian government spent on medical research that year.

Dr. Angela LaSalle with Fort Wayne Endocrinology concurs there are multiple medical conditions affected by weather, particularly migraines. When a storm front is on its way and the barometric pressure rises, it often triggers a migraine. But current research is finding other connections to health and weather, she said.

“NASA looks at that, how certain temperatures, pressure conditions and humidity may have effects on brain neurotransmitters.” Other weather-related information, not just patterns, affect health, LaSalle said.

“We know vitamin D is a major player in diabetes and heart disease, and people deficient in vitamin D tend to have more hormonal abnormalities,” she said, noting studies are finding possible connections between vitamin D deficiency and prostate and breast cancer. Sun exposure is critical to the formation of vitamin D in the body.

With advance knowledge of weather conditions, the patient who has weather-related medical conditions can go to the doctor and say, “‘What should I do so I don’t end up in the ER or your office?’” Bart said.

For example, one study examined ER visits during immediate post-thunderstorm periods. Researchers found a high correlation between ER visits in that timeframe by patients with asthma and discovered the majority failed to use their preventive asthma medications. Although they had access to them, most were using only rescue medications prior to the thunderstorms.

Had they been alerted to the coming weather conditions, they could have started preventive medications in the days prior to the storms, preventing costly ER visits.

Some changes to health caused by weather are “no brainers,” Bart said, such as worsening chest pain when a heart patient is walking in bitter cold temperatures.

“But what we’re saying is subtle changes in weather produce subtle changes in health,” Bart said. “Forewarned is forearmed. … We really hope this service will provide a small, but significant, improvement for people.”