Here is a blog I wrote for physiology regarding the major respiratory problems afflicting poor people.  Not surprisingly, they are strongly associated with exposure to smoke from cooking and heating.  I’m all for the romance of a nice big pot of stew over a medieval open fire, but would never want someone to get COPD or lung cancer for lack of another fuel option.  It’s important to realize the realities of the risks.  Obviously, we can’t get electricity to the entire world in an instant, however, we could try to find creative, cost effective, appropriate ways to reduce the risks.  I recommend reading the article, I drew entirely from its graphs and data.

It is estimated that 1.5-2 million people die annually due to respiratory problems associated with indoor pollution.  This occurs primarily in poor communities in the developing world, which rely on fuels such as coal, biomass, wood, dung, kerosene, and crop derivatives to cook meals.  The majority of cooking takes place inside homes and huts in many of these communities, concentrating the pollution.  This also increases exposure to the family members that spend much of their time around food preparation, typically women and children.  The majority of deaths are in children under the age of five, who acquire acute respiratory infections, asthma and other problems, while women are also prone to develop COPD and lung cancer.  Cooking with a wood fire for ten years or more is an independent risk factor for developing COPD.  It is estimated that 2.6%-3.6% of the global burden of disease is attributed to health problems related to cooking with solid fuels.  In fact, just as many deaths in poor to middle income countries are attributed to tobacco use as biomass fuels (although more men died from tobacco, and more women from biomass fuels).  According to the World Health Organization, up to 50% of households in Africa use solid fuels compared to under 5% of American households (in areas of low adult and infant mortality).  Over 75% of households in Asian countries from Iran, across SE Asia and throughout China, as well as African nations the Sahara and south rely on solid fuels.

Naturally, there is a variety among fuels in how many toxic byproducts are released into the atmosphere upon combustion, however, over 200 different chemicals have been identified, many of which are released in inhalable particles.  Below is listed proven toxic effects of wood smoke on animal models:

Acute: single exposures

Necrotizing tracheobronchial epithelial cell injury

Acute tracheobronchial and bronchiolar inflammatory response

Acute mucociliary dysfunction

Alveolar macrophage dysfunction

Airway hyperresponsiveness

Lung compliance reduction

Ventilatory response reduction

Subchronic: repeated exposures

Airway epithelial lining desquamation

Pulmonary edema

Neutrophilic peribronchiolar and perivascular infiltration


Lymphoid follicles hyperplasia

Late eosinophilia

Bacterial clearance reduction

Mild emphysema

Lung cancer


The mechanisms by which these particles do their damage include bronchial irritation, inflammation, increased reactivity, reduced mucociliary clearance, reduced macrophage response and reduced local immunity, binding hemoglobin to carboxyhemoglobin, carcinogenic damage, susceptibility to bacterial and lung infection, and even absorption of toxins into the eyes contributing to cataracts.

There are many possibilities for reducing the risk for people in poor communities, including but not limited to improved stoves and cleaner fuels.  However, even simple changes like improved ventilations in homes and dwellings could make a significant difference.  All efforts must thoroughly evaluate the cultural, economic and social impacts of any plans to change cooking and heating habits in poor communities.  Education plays a huge part in exposing people to the inherent risks associated with indoor pollution.  Changing the way the world cooks and heats over night is impossible, and improbable.  However, given the global impact that related respiratory problems has, it is an issue worthy of discussion and intervention.


Biomass Fuels and Respiratory Diseases

A Review of the Evidence

Carlos Torres-Duque, Darío Maldonado, Rogelio Pérez-Padilla, Majid Ezzati, Giovanni Viegi on behalf of the Forum of International Respiratory Societies (FIRS) Task Force on Health Effects of Biomass Exposure



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