Ozone production rate and hydrocarbon reactivity in 5 urban areas: A cause of high ozone concentration in Houston

Observations of ozone (O₃) and O₃ precursors taken from aircraft flights over Houston, TX, Nashville, TN; New York, NY; Phoenix, AZ, and Philadelphia, PA show that high concentrations of reactive volatile organic compounds (VOCs) in the Houston atmosphere lead to calculated O₃ production rates that are 2 to 5 times higher than in the other 4 cities even though NO_x concentrations are comparable. Within the Houston metropolitan area, concentrations of VOCs and O₃ production rates are highest in the Ship Channel region; the location of one of the largest petrochemical complexes in the world. As a consequence the concentration of O₃ in the Houston metropolitan area has recently exceeded 250 ppb, the highest value observed in the U.S within the past 5 years