Debbie Nicholson

Decrease of biomass smoke significantly reduces death from all causes

Researchers from Australia and Canada conduct the first study in evaluating the effect of reductions in air pollution from biomass smoke (smoke produced by domestic cooking and heating and woodland fires) on daily mortality.

View slideshow: Health effects from wood smoke.

Despite a vast amount of literature on the health effects of air pollution, few studies have investigated shifts in outcomes with public health interventions to improve ambient air quality. However, there have been no studies that reported reductions in deaths associated with interventions to reduce biomass smoke pollution, according to the study.

In this study researchers evaluated changes in mortality linked with an intervention to reduce ambient biomass smoke from domestic wood heaters.

In 2001, the Australian state of Tasmania was the setting for a series of interventions to reduce wood smoke pollution. During the late 1980s and early 1990s, wood stoves became increasing popular for home heating throughout Tasmania. The interventions dramatically accelerated a general trend towards using electric rather than wood heaters. As such, wood stove prevalence fell from 66% to 30% of all households and average particulate air pollution during winter was reduced by 40% (44 µg/m³ -- 27 µg/m³).

Using the data researchers had evaluated if there were any significant changes in all-cause, cardiovascular and respiratory mortality. The researchers compared the population of Launceston with the population of Hobart (also in Tasmania), which did not have any air quality interventions.

The reductions in mortality (deaths per 1,000 people each year and age adjustment) between 1994-2001 and 2001-2007 were not significant for males and females combined (2.7% for all-cause mortality; 4.9% for cardiovascular mortality; 8.5% respiratory mortality). However, reductions were statistically significant for males alone: differences of 11.4% for all-cause mortality; 17.9% for cardiovascular and 22.8% for respiratory.

Results taken during the winter months (June -- August) showed even higher reductions: cardiovascular 20%; respiratory 28%.

In their conclusion the researchers write; “Decreased air pollution from ambient biomass smoke was associated with reduced annual mortality in males and with reduced cardiovascular and respiratory mortality during winter months.”

The researchers note about the findings "highlight the potential for important public health gains from interventions to reduce ambient pollution from biomass smoke.

This study appears in the British Medical Journal.

According to the EPA “numerous scientific studies report potentially serious adverse health effects from breathing smoke emitted by residential wood combustion. Smoke contains fine particles, which can affect both the lungs and the heart. Residential wood smoke may be a significant source of exposure to fine particle pollution.

It is estimated more than one-third of Americans use fireplaces, wood stoves and other fuel-fired appliances as primary heat sources in their homes. This form of energy usage is associated with high levels of indoor air pollution and an increase in the incidence of respiratory infections, including pneumonia, tuberculosis and chronic obstructive pulmonary disease, low birth weight, cataracts, cardiovascular events and all-cause mortality both in adults and children.

To find out about the health effects of wood smoke can be viewed online at Environment and Human Health.


Slideshow; Health effects from wood smoke