What is the hazard of the yellow flame?

The yellow flame, often produced by incomplete combustion, indicates that the fuel is burning inefficiently, releasing soot and carbon monoxide. This can pose hazards such as poor indoor air quality and increased risk of fire due to the accumulation of flammable materials. Additionally, carbon monoxide is a toxic gas that can lead to serious health issues or even death if inhaled in significant amounts. Therefore, it's crucial to ensure proper ventilation and combustion efficiency to mitigate these risks.