Posted By Heather Aston Martin A quick Google search gives lots of references - most say between 40 and 70% is advised. Heather

Posted By Shelagh O'Sullivan Martin Above guidance is similar to mine (40-60%) - but some info to support it, may be of interest. High levels of humidity - (excess of 80% RH) -can impede the evaporation of sweat, thus restricting the body's ability to lose heat Low humidity - usually below 30% RH - can dry out mucous membranes, e.g. in throat and eyes,.Symptoms = soreness and a higher susceptibility to coughs and colds as a result of the loss of protection from the mucous membranes. Low humidity in offices can cause higher levels of airborne dust. This can exacerbate health problems by affecting bodily defences, creating a greater risk of respiratory illness. Also can increase static electricity from carpets and furniture. Not a serious hazard, but can cause discomfort, if the static discharges as a spark when touching metal objects, such as filing cabinets, door handles, etc. Previous threads on this forum on how to combat low humidity have helped me. Watch out when weather is very cold and dry. We have recorded <30%RH. Shelagh