Pesticides in fog.

The discovery of the very acidic nature of fog and clouds has created much interest in sampling, analysing, and elucidating the chemistry of fog, principally because an understanding of the chemical transformations leading to acid fog may provide important clues to the origin of acid rain. Recently, the knowledge of the chemistry of fog has expanded to include carbonyl compounds, volatile organic acids, and alkyl sulphonates. We have discovered that a variety of pesticides and their toxic alteration products are present in fog, and that they occasionally reach high concentrations relative to reported rainwater concentrations. In our experiments, we were able to measure the air-water distribution coefficients of pesticides between the liquid fog and the interstitial gas phase. These measurements reveal that some chemicals are enriched several thousandfold in the suspended liquid fog droplets compared to equilibrium distributions expected from Henry's Law coefficients for pure aqueous solutions.

Aircraft disinfection: the physical and insecticidal characteristics of (+)-phenothrin applied by aerosol at "blocks away".

A 2% formulation of (+)-phenothrin dispensed from 340-g or break-off tip aerosol cans was highly effective against mosquitos in aircraft disinsection trials. Two minutes after application at "blocks away", the mass median diameter of the dispersed drops was 5.1-6.2 mum. The concentration of the insecticide in the cabin fell to 10% of the original concentration after 9.2 min. No odour or irritation was caused by the use of this insecticide.