Final answer:
The most prevalent toxic gas produced in fires is Carbon Monoxide (CO). It is a colorless and odorless gas produced by the incomplete combustion of carbon-containing fuels, which binds with hemoglobin to reduce oxygen delivery in the body, and can be fatal at high levels.
Step-by-step explanation:
The most prevalent of the toxic gases produced in fires is Carbon Monoxide (CO). Carbon monoxide is a colorless and odorless gas that is produced by the incomplete combustion of carbon-containing fuels. It is extremely toxic since it bonds with hemoglobin in the blood, reducing oxygen delivery to the body's organs and tissues. In extreme cases, high levels of CO can lead to death. The toxicity of carbon monoxide stands in stark contrast to other gases mentioned such as methane and nitrogen, which are generally less toxic, and oxygen, which is necessary for life but is not a toxic gas.
In the context of fire gases and pollutants, carbon monoxide's major source is anthropogenic, with a significant proportion coming from automobile emissions. These emissions also typically contain nitrogen oxides, which when reacting with volatile organic compounds (VOCs) can form ozone, another harmful gas. Unlike nitrogen, which makes up a large portion of our atmosphere and is essential for life but generally not toxic, or oxygen, which is essential for life and combustion, carbon monoxide is a byproduct and is dangerous due to its harmful effects on human health.