Biomass is a renewable organic material from plants and animals, such as wood, agricultural crops, and household waste. The combustion of this organic matter releases its stored chemical energy as heat. This method is one of the oldest forms of energy production, used for everything from heating and cooking to generating electricity. Wood is the most common type of fuel used.
Sources of Biomass Burning
Biomass burning originates from both natural and human activities. Natural fires, often ignited by lightning, are a process in many ecosystems that can clear out dead vegetation, promote nutrient cycling, and trigger the germination of certain plant species. For instance, some pine cones require heat from a fire to open and release their seeds.
Human activities are responsible for the vast majority of biomass burning. In agriculture, fire is used to clear land for planting and to dispose of crop residues. Deforestation in tropical regions often involves “slash-and-burn” techniques, and a large portion of the global population relies on burning wood and charcoal for daily cooking and heating.
Chemical Composition of Smoke
Smoke from biomass burning is a complex mixture of gases and fine particles. A major component is greenhouse gases, including carbon dioxide (CO2) and methane (CH4), which trap heat in the atmosphere. The combustion also releases harmful gases such as carbon monoxide (CO) and nitrogen oxides (NOx), which contribute to smog.
Biomass smoke also contains large quantities of particulate matter (PM), which are tiny particles suspended in the air. The smallest of these, PM2.5, can be inhaled deep into the lungs. A specific type of PM is black carbon, or soot, produced from incomplete combustion.
Atmospheric and Climate Effects
Emissions from biomass burning impact atmospheric quality and the global climate. Plumes of smoke can create a regional haze that reduces visibility, degrades air quality, and contributes to smog.
The release of greenhouse gases from this burning disrupts the Earth’s carbon cycle. While vegetation regrowth can reabsorb some CO2, the scale of human-caused fires releases carbon into the atmosphere much faster than it can be removed, contributing to planetary warming.
Black carbon particles also play a potent role in climate change. These dark particles absorb sunlight, warming the atmosphere. When deposited on snow and ice, they reduce the surface’s reflectivity, an effect known as albedo. This causes the surface to absorb more solar radiation, which accelerates melting and contributes to further warming.
Human Health Consequences
Exposure to biomass smoke poses significant risks to human health. The most immediate impacts are on the respiratory system, causing irritation to the eyes, nose, and throat, and can lead to conditions like bronchitis and pneumonia. For individuals with pre-existing conditions such as asthma, smoke exposure can trigger severe attacks.
The health risks extend beyond the respiratory system. Fine particulate matter, PM2.5, is small enough to penetrate deep into the lungs and enter the bloodstream. Once in the circulatory system, these particles can cause inflammation and stress on the cardiovascular system, increasing the risk of heart attacks and strokes.
Certain populations are more vulnerable to the effects of biomass smoke. Children, the elderly, and individuals with pre-existing heart or lung diseases are at a higher risk. The global reliance on biomass for cooking and heating means women and children in developing countries are often disproportionately exposed to high levels of indoor air pollution.