Nearly four million people die prematurely every year from diseases attributable to household air pollution, primarily caused by cooking on open fires or inefficient cookstoves.

How does cooking create air pollution?

Across the developing world, many people rely on burning solid fuels, such as wood and charcoal, for cooking. Often this cooking is done on open fires or in inefficient cookstoves, producing a variety of gases and particles such as black carbon, organic carbon, methane, and carbon monoxide. Cooking in this way contributes significantly to both indoor and outdoor air pollution.

How does air pollution affect people’s health?

According to the World Health Organisation (WHO), in 2016 household air pollution was responsible for the deaths of 3.8 million people. The particles and gases emitted by inefficient cooking contribute to a range of heart and lung diseases including childhood pneumonia, chronic obstructive pulmonary disorder, coronary heart disease, stroke and lung cancer. In addition, there is emerging evidence that when pregnant women are exposed to household air pollution their babies are at increased risk for stillbirth, low birthweight, and decreased lung function.

How does air pollution affect the environment?

As well as causing disease, air pollution from cooking over open fires or with inefficient stoves contributes to global warming. There are three ways this happens:

  • The incomplete combustion of solid fuels and kerosene leads to the emission of greenhouse gases such as carbon monoxide and carbon dioxide.
  • Incomplete combustion also leads to the emission of short-lived climate pollutants such as black carbon and methane. Black carbon particles absorb sunlight, which warms the atmosphere. In addition, when black carbon particles fall back to earth they darken the surface of snow and ice. This reduces the extent to which these surfaces reflect sunlight and increases the rate at which sea ice and glaciers melt.
  • Inefficiently burning wood and charcoal for cooking leads to deforestation because more wood is needed to power the fire than if more efficient cooking methods were used. Harvesting wood faster than it can regrow reduces the ability of trees and shrubs to absorb carbon from the air. In this way, deforestation contributes to global warming. According to the Clean Cooking Alliance, approximately 30 percent of the woodfuel harvested globally is unsustainable, resulting in increased climate gases in the air equivalent to two percent of global emissions.

Forest degradation caused by unsustainably harvested woodfuel also negatively impacts biodiversity, erosion control and flood protection.

What can we do about it?

Replacing open fires or inefficient stoves with more modern stoves reduces emissions and exposure to pollutants. Fuels such as biogas, ethanol, liquid petroleum gas, and natural gas, along with electricity, are the most effective alternatives to solid fuels for improving air quality. However, these fuels and the stoves that burn them are often unaffordable for those who currently depend on solid fuels.

Alternatively, stoves which burn solid fuels but do so more efficiently than open fires can also improve air quality. However, the polluting emissions from many of these stoves are still higher than the guidelines set by the WHO. According to Kirk Smith, a professor of global environmental health at the University of California at Berkeley, “as yet, no biomass stove in the world is clean enough to be truly health protective in household use”.

Many attempts to increase the use of efficient cookstoves have not met with success. Writing for the Washington Post, Marc Gunther described how many women are reluctant to change cooking methods which are embedded in their culture. In addition, many of the efficient stoves promoted by non-profit organisations do not function as well in everyday use as they do when tested in the laboratory.

Many non-governmental organisations, governments and businesses are trying to reduce the harm people suffer from breathing in cooking smoke. However, there is disagreement about the best approach. Should they focus on promoting better biomass cookstoves as an imperfect but affordable way to reduce air pollution? Or should they focus solely on persuading people to switch to other, cleaner fuels? This remains a matter of debate.

Photo: MD Duran from Unsplash