This helps slow the spread of fires and hinders ignition of fires. Water vapor in the air, or high relative humidity values, help to keep fuel sources moist. Air is made-up of about 21% oxygen, 78% nitrogen and less than 1% other gases including carbon dioxide and water vapor.įire only needs about 16% oxygen to burn.
The last side of the fire triangle is oxygen. Large trees, on the other hand, take longer to ignite, but burn much more intensely. Thin dry fuels such as grasses can ignite very easily and burn quickly. Fuels are characterized by how much moisture is present to sizes, shapes, and quantity. This can be anything from grasses to large trees and timber. Fuel is any kind of material that will burn.
The next element in the fire triangle is the fuel source.
