It quickly reacts with ozone in sunlight (photooxidation) to form oxygenated products. α-Humulene has a very high reaction rate coefficient (1.17 × 10−14 cm3 molecule−1 s−1) compared to most monoterpenes. Since it contains three double bonds, first-, second- and third-generation products are possible that can each condense to form secondary organic aerosol. At typical tropospheric ozone mixing ratios of 30 ppb the lifetime of α-humulene is about 2 min, while the first- and second-generation products have average lifetimes of 1 h and 12.5 h, respectively.[24]