These are excellent airborne deodorizers, and super stars in green cleaning. Essential oils with a majority of monoterpenes are generally quick absorbing in topical blends because of the smaller molecular structure. They also have a shorter shelf life (1-3 years) and evaporate quickly. Oils high in monoterpenes are the conifer oils (alpha-pinene) and the citruses (d-limonene). As always, see individual oil profiles for specific uses.