The Dangers of Indoor Air Pollution

If you travel to undeveloped countries, you simply get used to the aroma of cooking fires, both outdoors and indoors. In fact, as I have globe-trotted over the past several decades, I have learned to readily differentiate between the cooking smells of one nation and the next. In India, for example, dried cow dung is a primary source of fuel for cooking fires. Its aroma is surprisingly pleasant, and the smell is everywhere. In the South Pacific, logs and coconut husks are typically used. These fires also smell pleasant, and they definitely evoke an atmosphere of rustic life.

Sadly, indoor cooking fires of these types kill as many as two million people annually, according to a new paper published in the October 14 issue of the journal Science. This means that indoor cooking fires kill more people than malaria, making this a very serious issue.

Home cooking fires generally employ wood, coal, dung or dried plant materials as fuel. Among these, coal is the most toxic, but all of these materials give off soot and smoke that fill the interiors of poorly-ventilated dwellings and fill the lungs and bronchial passages of people inside the dwellings. The result? Chronic pulmonary disorders, respiratory insufficiency, increased rates of serious respiratory infections and death by various forms of respiratory cancers.

According to the World Health Organization, indoor air pollution greatly increases the risk of both chronic obstructive pulmonary disease and acute respiratory infections in children. In developing nations, acute respiratory infection is the primary cause of death among children age five or under. WHO cites indoor air pollution from cooking fires as a major threat to health, contributing to low birth weight, high infant mortality, nasopharyngeal cancer, laryngeal cancer and lung cancer.

The researchers found that certain toxins are typically generated by home indoor cooking fires. Those toxins include:

1. Carbon monoxide – reduces oxygen delivery to major organs. When pregnant women breathe in carbon monoxide, this can lead to low fetal birth weight.

2. Polycyclic aromatic hydrocarbons – cancer-causing agents that increase rates of lung cancer, as well as cancers of the mouth, throat, nasopharynx and pharynx.

3. Nitrogen dioxide – significantly increases susceptibility to both bacterial and viral lung infections, and to reduced lung function.

4. Sulfur dioxide – produces wheezing, chronic obstructive pulmonary disease and cardiovascular disease.

5. Various airborne particles – produce bronchial irritation and inflammation and reduced immunity, wheezing, chronic bronchitis, and chronic obstructive pulmonary disease.

However, while indoor cooking fires represent a health hazard, they also perform some valuable functions beyond the cooking of food. Indoor cooking fires treat the insides of palm-thatch roofs with soot, reducing habitability for insects and thus reducing their numbers inside the homes. The fires also are typically the only source of heat in a poor home.

For these reasons, people in undeveloped areas rely heavily on fires for multiple purposes, which makes it difficult to end the practice.

But some strategies can significantly reduce cooking-related indoor air pollution. Most homes which use cooking fires have no ventilation for the smoke, such as a chimney or a vent. Such ventilation can greatly reduce exposure to toxins indoors.

Another approach is to cook food outdoors in a place where there is adequate ventilation and to avoid breathing smoke.

Finally, people could invest in a “solar cooker.” Costing approximately $3 dollars apiece, a solar cooker uses the energy of the sun to cook anything from rice and beans to meats, breads casseroles, and more. Solar cookers are becoming popular in Africa, where people are able to wean themselves from kerosene, which is a significant expense and the primary cause of home fires in undeveloped areas.

Supporting programs for solar cookers, improved ventilation and health education in undeveloped nations can help to reduce disease and mortality, and result in better lives for many people worldwide.

Chris Kilham is a medicine hunter who researches natural remedies all over the world, from the Amazon to Siberia. He teaches ethnobotany at the University of Massachusetts Amherst, where he is Explorer In Residence. Chris advises herbal, cosmetic and pharmaceutical companies and is a regular guest on radio and TV programs worldwide. His field research is largely sponsored by Naturex of Avignon, France. Read more at