From Burning Wood to Burdensome Breathing

COPD risk increased with regular wood and tobacco smoke exposure

(RxWiki News) As summer approaches, you're probably not thinking about lighting up your fireplace. But here's something to think about the next time cold weather rolls through: burning wood in your home could be damaging your lungs.

People who are regularly exposed to wood smoke may have a higher risk for chronic obstructive pulmonary disease (COPD), according to a study recently presented at a conference.

That study also showed that exposure to wood smoke may worsen symptoms of COPD.

In addition, regular exposure to both wood smoke and tobacco smoke appeared to increase these risks even further.

"Breathing issues?  Avoid being near burning wood."

According to Carlos Torres-Duque, MD, director of research at the Fundacion Neumologica Colombiana in Bogota, Columbia and lead author of this study, and his fellow researchers, "Forty percent of the world population use solid fuels (charcoal or biomass), especially wood, for cooking or heating." 

With that statistic in mind, Dr. Torres-Duque and colleagues conducted a study to better understand the characteristics of people with COPD related to wood smoke.

For their study, the researchers used data from the PREPOCOL study, which assessed rates of COPD among people older than 40 years from five cities in Colombia.

The study included 5,539 participants. Nearly 9 percent of these participants were diagnosed with COPD.

Each participant answered a respiratory questionnaire that asked questions about wood smoke exposure. Participants also performed spirometry, a simple diagnostic tool that measures how much air a patient can inhale and exhale.

The participants were split into four groups: those who were exposed to wood smoke but never smoked tobacco (30.9 percent), those who were exposed to tobacco smoke but not exposed to wood smoke (18.7 percent), those exposed to both wood and tobacco smoke (29.8 percent) and those who were not exposed to either type of smoke (20.6 percent).

The rates of COPD overall and according to smoke exposure were as follows:

  • 8.9 percent among all study participants
  • 6.7 percent among those exposed to wood smoke only
  • 7.8 percent among those exposed to tobacco smoke only
  • 16 percent among those exposed to both wood smoke and tobacco smoke

The researchers found that rates of COPD climbed as the length of wood smoke exposure increased.

Then the researchers adjusted their analysis for other factors, including age, active and passive tobacco smoking, level of education, history of tuberculosis and altitude.

They found that exposure to wood smoke for 10 or more years was associated with 1.5 times the odds of developing COPD.

Among people with COPD, those exposed to wood smoke only were more likely to be female, to be shorter and to have a higher body mass index (ratio of weight to height), compared to those exposed to tobacco smoke only and those exposed to both types of smoke.

COPD patients exposed to both wood smoke and tobacco smoke had worse COPD symptoms than those exposed to tobacco smoke only or wood smoke only. More specifically, COPD patients exposed to both types of smoke had poorer scores on lung function tests, produced more phlegm and coughed more frequently.

"In the population we studied, exposure to wood smoke was identified as an independent risk factor for developing COPD, both in women and men," said Dr. Torres-Duque in a press statement. "In addition, the prevalence of COPD was significantly higher in those who were exposed to both wood and tobacco smoke and those with both exposures had more symptoms and more severe disease than those who were exposed to only one type of smoke."

According to Dr. Torres-Duque, these findings suggest that the combination of wood and tobacco smoke may lead to even higher rates of COPD and a greater frequency of COPD symptoms.

Even though Americans don't rely on wood burning for heat as much as people in other parts of the world, this study has important implications for many of us, especially as COPD has become the third leading cause of death among Americans.

In 2008, the American Lung Association issued a warning about the harmful effects of burning wood, both inside and outside the home.

"Wood smoke poses a special threat to people with asthma and COPD and should be actively avoided by those with lung disease," the organization warned. "When possible, the American Lung Association strongly recommends using cleaner, less toxic sources of heat. Converting a wood-burning fireplace or stove to use either natural gas or propane will eliminate exposure to the dangerous toxins wood burning generates including dioxin, arsenic and formaldehyde."

State governments around the US have also warned residents about the lung-related dangers of wood burning. For example, Maine's Center for Disease Control says, "[S]moke from wood burning can cause air pollution and public health problems. It can cause or make worse asthma, chronic obstructive pulmonary disease, and heart disease. It affects children and the elderly more than others."

Dr. Torres-Duque said that future research might show how people respond differently to smoke exposure and which treatments work best for different types of exposure.

The study by Dr. Torres-Duque and colleagues was presented at the American Thoracic Society's international conference. The research has yet to be published in a peer-reviewed journal.

Funding information and author disclosures were unavailable.

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Review Date: 
May 16, 2013