Dear Editor,

Psoriasis is a chronic disease, the prevalence of which shows geographic variations,1 suggesting that it might be influenced by climatic factors such as sun exposure and humidity.2 ,3 In order to assess the effect of weather and both outdoor and indoor environmental factors on the clinical course of psoriasis, we analysed the answers given to a specific questionnaire administered to 300 consecutive patients attending the psoriasis outpatient clinic of our department. The role of exposure to rainy, windy, muggy, hot, cold and sunny climates, as well as of seasonality in relation to the outdoor environment and the effect of domestic heating and ventilation systems …