Alkene emissions from the petrochemical industry contribute significantly to ozone production in the greater Houston area but are underestimated in emission inventories. It is not well-known which processes (e.g., fugitive emissions, chemical flare emissions, etc.) are responsible for these underreported emissions. We use fast time response and ground-based mobile measurements of numerous trace gas species to characterize alkene plumes from three identified chemical flares in the greater Houston area. We calculate the combustion efficiency and destruction and removal efficiency (DRE) values of these flares using the carbon balance method. All three flares were operating at DRE values lower than required by regulation. An examination of photochemistry in flare exhaust plumes indicates that the impact of direct formaldehyde emissions from flares on ozone formation is small as compared to the impact of alkene emissions.