Fire Related Particles
The smoke plume from an uncontrolled fire contains particles and gases as it leaves the combustion zone. The gases include water vapor, carbon
dioxide, carbon monoxide, nitrogen oxides if the combustion zone is hot enough, and volatile organic compounds. The volatile organic compounds begin
as gases but much of those materials will condense or sorb onto the particles in the plume. Some will stay in the gaseous state. The particles
from combustion include charred and coked fuel, pyrolized associated materials, and agglomerates of "soot" and condensed organic compounds. The
distribution of the materials associated with the plume at the receptor site will depend on the size of the particles, their sticking coefficient
relative to the surface they contact, distance from the fire, and time of transit from the combustion zone to the receptor. The particles from the
smoke plume leave a signature at the receptor site that can often be used to determine the impact of the fire at that location. The signature at the
receptor site will change with time so sampling at the receptor site soon after exposure is most desirable, though some evidence of exposure may
persist for years.
The materials covered here are related to uncontrolled fires and not controlled combustion sources. Emissions from internal combustion and diesel
engins, boilers of all types, and smoking of tobacco or other plants are not included here. Emissions from fireplaces, wildfires, house fires,
industrial fires, field burning, and yard waste fires are included. Wildfires include forest fires and brush fires.
Backdrafting in the fireplace or a leaking chimney will emit materials from the fire in the fireplace into the living zone of the building.
Fireplace emissions are dominated by spalled coked wood cells and a relative absence of other charred plant material. The intent of burning wood in
a fireplace is to consume all of the core of the wood. This is distinct from wild fire that burns the outside of the plant and tends to leave the
charred core. Fireplace debris is defficient in pyrolized phytoliths and burnt clay compared to forest fire smoke. Burning waste materials in
the fireplace will add to the complexity of the emissions but will not add phytoliths or burnt clay.