Air pollution interferes with plant olfactory communication by accelerating the breakdown of volatile compounds. However, a recent study published in Science suggests that the effects of pollution are not as simple as they seem.

Plants use volatile organic compounds (VOCs) to communicate. ‘These are what we call specialised metabolites’, says Petra Bleeker, assistant professor of plant-insect interactions at the University of Amsterdam. These include terpenes, aromatic compounds, fatty acid catabolites and amino acid derivatives. ‘A plant produces these in interaction with its environment’,” explains Bleeker. Bees, for example, use plant volatiles to navigate around flowers containing nectar.

But once released, these volatiles have a short life span. UV radiation from the sun, together with ozone (O3) and atmospheric radicals such as hydroxyl radicals (OH) and nitrogen radicals (NOx), trigger their degradation. The radicals react with the carbon-carbon double bonds present in scents to produce a range of degradation products. The rate at which this happens depends on the concentration of volatile compounds and radicals.