Impacts of biogenic emissions on photochemical ozone production in Houston, Texas

The effects of isoprene and monoterpene emissions on O₃ photochemistry in this region were investigated. Isoprene emissions played an important role in O₃ formation when the O₃ plume occurred in the afternoon over the urban Houston area.

When the isoprene emissions were decreased or increased by 50%, the O₃ concentration was decreased or increased by 5–25 ppb over the urban Houston area, respectively, but the change in the O₃ concentration was less than 5–10 ppb over the industrial Ship Channel. Additional sensitivity studies showed that the surface O₃ change resulted primarily from local isoprene emissions, although transport of isoprene from the north of the urban Houston area was found to be nonnegligible in the isoprene budget on several days.