Jamie and Marty O'Link's four-bedroom house is nestled among a wooded area in St. Cloud overlooking a Mississippi River channel. They built it almost 20 years ago.
A fire pit and piles of wood stacked in their back yard remind them of a time when they romanticized the smell of wood smoke. Their next-door neighbors used to heat their home with wood throughout the entire winter, and the constant smoke that traveled to the O'Link's home all those years became a nuisance.
That nuisance may be the primary factor behind Jamie's health problems. Earlier this year during her annual physical, her doctor had some bad news.
"She basically told me I have chronic obstructive pulmonary disease," Jaime said. Her doctor told her that it was more commonly known as emphysema, and that Jamie had to stop smoking.
"But I don't smoke," Jaime told her doctor.
Jamie has never smoked and neither has her husband, although her parents smoked when she was a kid. At 52, she still maintains a pretty athletic lifestyle. Her doctor told her she likely got sick from her constant exposure to wood smoke during the past twenty winters. That's because wood smoke contains fine particles and several gases known to be harmful to a person's health.
"It's very similar to the smoke from tobacco smoke that we know is harmful," said Chuck Stroebel, a research scientist with the Minnesota Department of Health. Stroebel said most people are familiar with wood smoke's short-term, mild effects, such as burning eyes and breathing problems.
"But the fine particles and other pollutants from wood smoke may also trigger more serious respiratory effects like asthma, bronchitis, emphysema," Stroebel said.
Stroebel said emerging research shows that exposure to the fine particles from wood smoke and other air pollution sources are associated with increased risk of cardiovascular problems, like heart attacks and heart arrhythmias.
"This is because the particles in the wood smoke are so small that they get into the deep parts of the lung," Stroebel said. "And then [those particles] can actually get into the blood stream and then enter systemic circulation."
Stroebel said it's hard to definitively link a particular exposure to a health problem, but said a growing body of evidence points to a strong relationship between levels of fine particles in the air and various health problems. Stroebel notes that smoke can travel distances, and wood smoke adds to the other sources of fine particles in the air. That includes emissions from vehicles and power plants.
Those fine particles and gases are still a concern even with wood-heating devices that are newer or have the EPA's stamp of approval.
John Seltz is with the air policy unit at the Minnesota Pollution Control Agency. He said newer, certified wood stove models made since 1988 are about three times cleaner than older ones and require less wood. But he still cautions their use.
"A new style wood stove still emits maybe 100 to 150 times more particulate matter than a gas furnace or an oil furnace, so there is still a fair amount more pollution coming out of the wood burning appliance," Seltz said.
Seltz said the same is true of EPA-certified outdoor wood boilers, the wood heating device that's the biggest concern among environmental and health experts. There is no certification requirement for outdoor wood boilers but the EPA has a voluntary certification program.
When homeowners are evaluating how to heat their homes, Seltz said there's always a trade-off.
"Certainly burning wood does reduce the carbon footprint because burning a renewable fuel reduces the overall carbon emissions, but there is this counter-veiling concern about particulate matter in the air and the direct health effects, so there is a balancing act," Seltz said.
Back at the O'Link's, Jamie and Marty said they initially weren't looking forward to this winter. But, once they sat down with their neighbors to explain why it was important for Jamie to minimize her exposure to smoke, the neighbors agreed to limit heating their home with wood this year.
"We are so grateful to our neighbors. It has been wonderful," Jamie said.
"We've been able to sit in our screened-in porch right through the cool season," Marty O'Link said.
The O'Links said they hope state agencies will do more to educate people about the health effects of wood smoke. According to a residential wood combustion report by the Minnesota Pollution Control Agency, more than half a dozen Minnesota municipalities have adopted or are considering ordinances that address residential wood combustion. These municipalities have approached the issue from issuing permit requirements and separation distances to outright bans.