Wood Smoke Linked to COPD and Asthma

The following was originally published at healthcentral.com/asthma. 

Wood fires have been used for heating and cooking for most of history. Even today they continue to be used, sometimes for fun and entertainment, although often as a much needed source of heating and cooking. The problem, though, lies in the smoke created, which has now been linked to asthma and COPD.

What is wood smoke?  

Well, most poeple know what wood smoke is.  Still, the technical name for wood smoke is biomass smoke.  Biomass is fuel created from living or recently living organisms, such as trees, plants, animal dung, charcoal and coal. Biomass smoke comes from wood stoves, fireplaces, campfires, wildfires, and leaf burning.  It also comes from cigarettes and cigars.

Biomass contains carbon, hydrogen and oxygen. Biomass burning, called combustion, results in a series of chemical reactions that turn carbon, hydrogen and oxygen into carbon dioxide, water and heat. However, due to incomplete combustion, the reaction also releases pollutants into the smoke created.

These include:

• Harmful Chemicals.  These include carbon monoxide, formaldehyde, benzene, toluene, acrolein, methane, and methyl chloride.  These may irritate cells lining your respiratory tract to trigger asthma attacks and COPD flare-ups.
• Particulate Matter.  These are solid and liquid particles of incompletely burned wood, many of which are small enough to be inhaled deep into airways. Like chemicals, they may also irritate cells lining your respiratory track to trigger attacks and flare-ups. 

What do the studies show?  

A great deal of studies have pretty much confirmed the link between wood smoke and respiratory diseases like asthma and COPD. As a matter of fact, wood smoke may trigger asthma attacks and COPD flare-ups, and it may also cause asthma and COPD, just like cigarette smoke does.

Studies have also linked inhaling wood smoke with:

• Small birth weight, which has also been linked to asthma and to COPD
• Respiratory infections like pneumonia, which may trigger asthma and COPD
• Lower respiratory tract infections in children, including pneumonia and bronchiolitis, which are also linked with the development of lung disease later in life
• Increased incidence of strokes and heart problems
• Eye disease, as smoke also irritates cells lining your eyes
• Cancer, such as lung cancer
• Headaches

How does wood smoke cause respiratory complications?

Acute Exposure. Inhalation of certain chemicals and particulate matter may irritate airways, triggering an immune response.  This sets off a series of chemical reactions that cause cells lining airways to become inflamed.  This irritation results in asthma and COPD symptoms like wheezing, coughing, and shortness of breath.

Chronic Exposure.  Exposure to biomass smoke day after day after day may cause this inflammation to become chronic, such as what occurs in asthmatic airways. Chronically inflamed airways may also cause scarring that makes airways thicker.  It may also result in loss of lung tissue. These are patterns that result in airflow limitation, or COPD.

What circumstances increase your risk for developing health problems due to smoke inhalation?  

Cold Weather.  Molecules in hot air are farther apart, and so warm air tends to rise. This makes it so smoke created from a campfire on a warm summer day is likely to rise away from people, and therefore is less likely to cause problems. Molecules in cold air are bundled together, and so cold air tends to stick near the ground. So smoke on a cold day tends to linger near the ground and is more likely to be inhaled. So, if you have a lung disease, some alternative source of heat may be beneficial.

Enclosed Spaces. During winter months, when it’s cold outside, people tend to keep their windows and doors shut. This makes it so wood smoke lingers inside homes, increasing the likelihood of it being inhaled. One study actually showed that women who spent years cooking over wood fires had an elevated incidence of respiratory complications. So it’s best to avoid using wood stoves and fireplaces, although if you must use them, keep a window open to improve ventilation.

Neighborhoods.  Of course if you have a wood stove or fireplace in your home, you are at the greatest risk of inhaling wood smoke.  However, if you do not burn wood in your home and your neighbor does, smoke may enter your home even with closed windows and doors.  This may be especially true on cold days. Some neighborhoods may solve this problem with bans on wood stoves and fire pits.

Poverty.  Wood heat is convenient and it’s also relatively inexpensive. This is nice for people in poverty, and it’s also nice for people in underdeveloped countries. Unfortunately, this also leads to indoor air pollution and an increased incidence of the complications of inhaling it. About three billion people continue to heat and cook using biomass fuel.

What does this mean?  Surely this may be difficult for some people, although it basically shows the need to limit exposure to wood smoke, especially if you have a family history of respiratory diseases, and especially if you already have a diagnosis of asthma or COPD. Alternative sources of heat, include gas, electricity, and heating oil. 

References and further reading:

• 6 Tips to Help You Quit Smoking
• 7 Things That May Cause COPD
• PubMed: Wood smoke exposure and risk of chronic pulmonary disease
• PubMed: Exposure to biomass smoke as a cause for airway disease in women and children.
• NCBI: Indoor air pollution from biomass fuel smoke is a major health concern in the developing world
• CDC: Biomass smoke exposure: health outcomes measures and study design
• WHO: Biomass Pollution Basics
• WHO: Household Air Pollution and Health
• State of Washington: How Wood Smoke Harms Your Health