Burning human waste occurs in situations like poor sanitation or survival, but the resulting fumes are highly toxic and pose immediate and long-term dangers. The combustion of feces in open air is inefficient, producing a dark, noxious smoke stream laden with dangerous chemicals and microscopic particles. Inhaling these fumes can lead to serious respiratory illness, systemic chemical poisoning, and the spread of infectious disease.
The Chemical Composition of Feces
The danger of burning feces begins with its physical and chemical makeup, which is unsuitable for clean combustion. Fresh human waste has a median water content of approximately 74.6%, which prevents the material from reaching the high temperatures required for complete and clean burning.
The solid matter consists largely of complex organic compounds, including protein residues, fats, carbohydrates, and undigested fiber. A significant portion of this dry matter is composed of bacterial biomass. When this wet, dense organic mix is heated, it does not burn cleanly but instead smolders and undergoes pyrolysis, releasing a dense, toxic smoke.
Human feces are also a reservoir for numerous pathogenic organisms, including bacteria, viruses, and parasite eggs. A single gram of human waste can contain millions of these pathogens, which are responsible for infectious diseases like hepatitis A, E. coli, and norovirus. When the waste is heated but not fully incinerated, these pathogens can become aerosolized and escape into the smoke plume.
Harmful Substances Released During Incomplete Combustion
The open burning of organic material, particularly wet waste, results in incomplete combustion, which generates the most dangerous pollutants. This process occurs because the fire temperature is too low and the oxygen supply is insufficient to break down all the compounds into harmless carbon dioxide and water vapor. Instead, the heat causes the organic matter to decompose into a complex mixture of toxic gases and fine particles.
One of the most immediate dangers is Carbon Monoxide (\(\text{CO}\)), an odorless gas that replaces oxygen in the bloodstream, leading to asphyxiation. Studies of combustion under similar conditions have shown that this incomplete burning produces a high concentration of \(\text{CO}\). Other gaseous pollutants include nitrogen oxides (\(\text{NO}_x\)) and sulfur dioxide (\(\text{SO}_2\)), which are powerful irritants that can damage the lining of the lungs and respiratory tract.
The incomplete breakdown of complex organic molecules releases a vast array of volatile organic compounds (\(\text{VOCs}\)) and semi-volatile organic compounds. These include polycyclic aromatic hydrocarbons (\(\text{PAHs}\)), which are known carcinogens, and potentially even trace amounts of highly toxic chemicals like dioxins and furans if any chlorine-containing materials were mixed with the waste. The presence of these toxins makes the smoke a systemic chemical hazard, not just a respiratory one.
Crucially, the smoke is heavily loaded with Particulate Matter (\(\text{PM}\)), which are microscopic solid and liquid droplets suspended in the air. These particles are categorized by size, with \(\text{PM}_{10}\) being inhalable and \(\text{PM}_{2.5}\) being especially hazardous because its tiny size allows it to penetrate deep into the lower respiratory tract and lungs. Furthermore, the relatively low burn temperatures often achieved in open fires are insufficient to sterilize the waste, allowing infectious agents to survive and become airborne within the smoke.
Health Consequences of Inhaling Fumes and Particulates
Exposure to the fumes from burning feces can cause a range of health issues, which are generally divided into acute and chronic effects. Acute, or immediate, symptoms are typically inflammatory and irritant responses to the gaseous and particulate components of the smoke. These include burning eyes, throat irritation, coughing, and difficulty breathing, which usually resolve soon after exposure ends.
Inhalation of carbon monoxide can rapidly lead to headaches, dizziness, and nausea, representing the early signs of \(\text{CO}\) poisoning, which reduces the blood’s ability to carry oxygen. Individuals with pre-existing conditions, such as asthma or chronic obstructive pulmonary disease, may experience a rapid and severe worsening of their symptoms due to the irritant gases and particulate load.
Prolonged or repeated exposure to the fine particulate matter (\(\text{PM}_{2.5}\)) and chemical toxins carries far more serious chronic risks. Over time, consistent exposure increases the risk of developing long-term respiratory diseases, including chronic bronchitis and a rare but severe disease called constrictive bronchiolitis. The deep penetration of \(\text{PM}_{2.5}\) into the lungs can also lead to systemic inflammation and an elevated risk of cardiovascular problems, including heart disease. The \(\text{PAHs}\) and other organic toxins in the smoke are linked to increased lifetime cancer risk.
Safer Methods for Waste Management
Given the severe toxicity of burning feces, safer, non-combustion methods must be used for waste management.
Burial (Cat Hole)
The most widely accepted and simple method in outdoor or temporary settings is burial in a small excavation known as a cat hole. This hole should be dug 6 to 8 inches deep and located at least 200 feet away from any water sources, trails, or camp areas to prevent contamination.
Containment Systems
In environments where burial is impractical, such as arid deserts or areas with thin soil, the safest method is to “pack it out” using specialized containment systems. Commercial waste alleviation and gelling (\(\text{WAG}\)) bags or similar portable toilet systems are designed to contain, chemically treat, and solidify the waste for safe transport and disposal in a designated facility. For situations requiring more extended use, a twin bucket system can be established, where waste is contained in a lined bucket and covered with a carbon material like sawdust or wood chips to manage odor and aid decomposition. These methods prioritize sanitation and containment, preventing the release of both pathogens and toxic combustion products into the environment.