Clinical Scenario 4 for Particle Pollution

An older man, a patient of yours, comes to your office in early spring complaining of frequent cough with phlegm, which he has developed over the recent months. He stopped smoking 30 years ago. He casually mentions that he is at times short of breath when bringing firewood into the house, but "the cord of wood is almost gone by this time of year.” He also mentions that he has noticed his wife coughing more often than is usual, though otherwise she is doing fine. He is taking high blood pressure medication and occasionally over-the-counter pain relievers.

You saw him in early fall for a routine annual check-up. At that time, he was doing well and, apart from controlled blood pressure and minor aches, had no major complaints. He has mild COPD not requiring medication. His spirometric parameters (FEV₁, FEV₁/FVC) were at the lower limit of normal for his age but FEF_25-75 was reduced. On this visit, he has no fever, chest discomfort, or changes in bodily functions. However, his FEV₁ is about 5 percent lower than it was when you saw him six months ago. A chest film shows mild hyperinflation but no masses or infiltrates.

Discussion

We spend about 80 percent of the time indoors. Older adults spend even more time indoors than younger people, particularly during winter. Burning of wood produces an array of harmful air pollutants, including ultrafine (PM_0.1) and fine particle pollution (PM_2.5), carbon monoxide (CO), nitrogen dioxide (NO₂), organic and elemental carbon, aldehydes, and other volatile organic compounds. Wildland and agricultural fires produce similar mixtures of toxic air pollutants.  On a mass basis, ultrafine and fine particle concentration is about equal. However, based on the number of particles, the ultrafines make up 70 to 80 percent of the total smoke particles. The ultrafines are thought to be the most hazardous to human health and can easily reach the alveolar region. Many of the smoke compounds are airway irritants and carcinogens (Naeher et al., 2007).

In controlled wood smoke exposure studies, healthy individuals show—after four hours of exposure—an increase in several markers of airway and systemic inflammation in serum and plasma (Barregard et al., 2006, Sallsten et al., 2006). Numerous epidemiological studies report increased daily hospital admissions and emergency visits of people with asthma associated with exposure to wood smoke. Other studies show an increase in respiratory symptoms as well as reduction in pulmonary function among people with asthma when exposed to wood smoke repeatedly (Boman et al., 2003). Residential wood smoke is also associated with adverse respiratory effects such as shortness of breath in subjects with COPD (Harre et al., 1997).

Balanced response

Although the development of cough and sputum, plus increased dyspnea upon exertion in a patient who is a former smoker with mild obstructive impairment, might represent a COPD “exacerbation,” you should consider exposure to wood smoke due to a frequent use of a fireplace or wood-burning stove for heating or cooking. Suggest reduction in the use of the fireplace or wood-burning stove in the future, along with proper operation and maintenance when using a wood-burning appliance:

• Wood should be dry and seasoned before using because wet wood produces more particle pollution and burns less efficiently. Wood should have 20 percent or less moisture. Moisture meters allow you to test the moisture level in wood and cost as little as $20.
• The fireplace or wood-burning stove (including the chimney) should be cleaned and inspected annually for proper functioning.
• Improved ventilation to the outdoors from the stove area and improved chimney draught should reduce the concentration of respirable particulates.  

These and other tips are addressed on EPA's Burn Wise website at www.epa.gov/burnwise.