The risk of lung cancer increases with the length and amount of exposure. The health effects from inhaling particles depend on many factors, including the chemical makeup and size of the particles. Sulfur dioxide irritates the eyes, nose, and the respiratory tract at low levels of exposure. At high levels, it causes the lung airways to narrow. This results in chest tightness, wheezing, or breathing problems.
Combustion always produces water vapor.
Although water vapor is not usually considered a pollutant, it can act as one. It can result in high humidity and wet surfaces. These conditions encourage the growth of biological pollutants such as house dust mites, molds, and bacteria. Avoid using unvented, fuel-burning devices in enclosed spaces. Unvented, fuel-burning space heaters should only be used in emergencies.