What effect does an increase in vapor pressure have on explosion risk?

An increase in vapor pressure is directly related to an increase in the concentration of flammable vapors in the air. Vapor pressure refers to the tendency of a substance to evaporate; thus, as vapor pressure increases, more molecules enter the gas phase, resulting in a higher concentration of vapor in the air.

When the concentration of flammable vapors is elevated, it raises the likelihood that these vapors can reach flammable levels when mixed with air. This is critical in assessing explosion risk because an adequate concentration of flammable vapors is necessary for combustion. Therefore, a higher vapor pressure contributes significantly to an increased risk of explosions, particularly in enclosed or poorly ventilated spaces.

Considering the other options, an increased vapor pressure does not decrease explosion risk, and it certainly affects explosions—leading to a heightened risk rather than having no effect. Additionally, it does not reduce the flammable range of gases; instead, it can expand the flammable limits by providing sufficient vapor concentration needed for ignition.