Relative humidity and fuel moisture levels are critical indicators. Which one of these statements is true?

The correct statement is that high relative humidity aids in fire safety.

Relative humidity affects the moisture content in the air, which in turn influences the rate of evaporation from fuels. When relative humidity is high, it generally means that the air is more saturated with moisture. This increased moisture can result in drier fuels absorbing less water, leading to reduced fire intensity and lower chances of ignition. Conversely, low relative humidity can lead to drier fuels that ignite more easily and burn more fiercely.

While it might seem that low humidity with high fuel moisture would mitigate fire dangers, it’s the balance of both that is essential. High moisture in the fuels under low humidity conditions may still allow for rapid fire spread because the dryness of the air promotes further moisture loss from the fuels. Therefore, high relative humidity is vital for fire safety as it helps maintain fuel moisture levels, thereby reducing the likelihood of fire ignitions and spread.