Figure 1. The effects of diesel exhaust pollution upon the abundance of a synthetic oilseed rape floral odour blend.

(a), An oilseed rape flower (photographed by RDG). (b), Percentages of each component of the synthetic floral blend, replicating the ratio at which they are naturally emitted from oilseed rape flowers. The colours and letters that represent each chemical are consistent throughout the figure. (c–j), Mean volatile abundances (±s.e.m) of the eight synthetic floral chemicals in ambient ‘clean’ air (darker lines) compared to their abundances in diesel exhaust polluted air (lighter lines) at four different times points after exposure (n = 5). (k), The changes in mean floral chemical abundance in diesel exhaust polluted air relative to ambient air; which were either statistically significant (_▾; P ≤ 0.05), or in the case of both α-terpinene and α-farnesene where the chemical was no longer detectable in diesel exhaust polluted air (▾). Directions of arrowheads indicate either increases or reductions in relative abundance.