While browsing my old volumes of Panama Canal Reviews, I came across this one that has sparked much controversy lately amongst us Zonians. If the Health Bureau only knew what they were doing to us back then!!!

Photo and article from The Panama Canal Review - July 2, 1954 article titled "Communities Are In A Fog When Spray Truck Makes Rounds".

     Twice a week these days when the nasty biting Aedes taeniorhynchus mosquitoes and the pestiferous sand flies are at their meanest, the Canal's fog machines roll through local communities. Fish fanciers hurry to cover their aquariums and persons suffering from asthma take to their dry closets. But for a while, at least, after the truck has passed the biting insect pests are no nuisance.
     Experts disagree as to the effectiveness of this type of machine for the use to which it is put, but Canal Health officials report that the fog does afford at least temporary relief. It may be because it is effective as an insect repellent rather than a killing agent since when DDT is dispersed in fog it has no residual effect.
     The material used by the spray truck, or fog machine, is a solution of DDT in diesel oil. It is atomized mechanically, the experts explain, by compressed air into a fine mist or spray which is turned into fog by a blast of high velocity hot air as it leaves the nozzle. The DDT is the killing or repellent agent; the oil is merely its solvent.
     Evening hours have been chosen for use of the spray truck because daytime rising air currents keep the fog from remaining in contact with the ground long enough to be effective.
     Health Bureau officials have worked out a schedule for the machine in an attempt to minimize its hazard to traffic which, naturally, is impeded by the fog. In the towns where traffic is heaviest, such as Balboa and Diablo Heights, the truck makes its rounds as early in the evening as possible, preferably before dark. In towns such as Gamboa, where street traffic is lighter; the spraying is done at later hours when the DDT fog is believed to be more effective.