Where unburned carbon particles or inert materials such as ash are present in the combustion exhaust, they are usually visible as coloration or ‘smoke’. Any combustion process that uses solid or liquid fuels can generate solid particles if incorrectly designed or operated, and the degree to which particles are visible in the exhaust is often a warning sign that the combustion process is not being controlled correctly.
Most particles ultimately settle on surfaces around the point of discharge to atmosphere. They cause environmental damage only if they are toxic, corrosive or produced in large quantities. However, while airborne, they present a hazard to respiratory systems, and the sight of airborne smoke is frequently regarded as an intrusion on the local environment.
Previous: Nitrogen oxides
Next: Other compounds