Technical consultation on specifications and quality control of netting materials and mosquito nets
a. Additional investigations of burn behaviour and impact of flame retardants should be undertaken.
4.7 Air permeability
It was agreed that air permeability should not be included in the WHO specifications, as comfort is highly culture- and climate-dependent and, as yet, no study data are available on consumer preferences for air permeability.
a. Industry should carry out research on comfort in relation to air permeability and moisture/vapour permeability of netting materials.
4.8 Water and insecticide uptake
Mosquito nets may be treated in the field by dipping in a dilution of insecticide formulation in water. To ensure correct dosing when nets are treated individually, the volume of diluted insecticide prepared should match the water uptake of the net, especially if an insecticide treatment kit is “bundled” with the net. If water uptake is unexpectedly high, parts of the net will not be properly treated, whereas if uptake is unexpectedly low, the dose rate may be too low and, as such the excess liquid must be disposed of safely. Water uptake of a net is influenced by the type of yarn used and its pre- treatment in the factory (e.g. addition of oils or other finishing products) and should be stated on the label and packaging of the net.
At present, only polyester netting made from fibres with a filament count of above 30 is known to provide the appropriate characteristics for insecticide treatment at field level, and thus can be recommended for this purpose. According to WHO, 0.5 litre of insecticide formulation diluted in water should be used to treat a polyester net and 2 litres should be used for a cotton net∗.
Instructions for treatment and use of insecticide-treated mosquito nets. WHO/CDS/WHOPES/GCDPP/2002.4, WHO, Geneva, 2002.