Liquefied petroleum gas effect on ozone formation in Mexico city

An experimental study of outdoor smog chambers was carried out to determine effects of liquefied petroleum gas (LPG) on maximum ozone (O3 max). 60% additions of commercial LPG and 60%-propane/40% butane mixture of the initial concentration were introduced into eight smog chambers containing morning ambient air of Mexico City metropolitan area (MCMA). The ozone concentrations in each chamber were monitored throughout the day to determine the maximum of ozone. Dilution experiments of 50% total hydrocarbons and associated compounds to LPG in morning ambient air were carried out too. The results showed, that by increasing 60% of the associated compounds to LPG in the air of MCMA or diminishing 50% of them, had not an appreciable influence. The largest effect on ozone formation is determined by total nonmethane hydrocarbon (tNMHC) contained in the atmosphere, being the maximum of ozone formed in the smog chambers, on the average it diminished a 55%. C3 and C4 compounds associated to LPG only contribute a 14% of the total ozone formation.