Improved hand hygiene is known to reduce transmission of both respiratory (RTI) and gastrointestinal infections (GTI) under "semi-closed" conditions such as hospitals, day-care centres and schools. It is not known if similar interventions would have the desired effect in a regular office work. This study is aiming to investigate this possibility by recruiting volunteers from several companies in the Helsinki Region. The two intervention groups will receive detailed instructions e.g. for proper coughing and sneezing, and for regular cleaning of hands with either standard liquid soap or with alcohol-based gel rubbing. Third group will serve as the control and is advised not to change their previous behaviour in this respect. The participants will report weekly possible RTI or GTI symptoms and related days off through internet. The study is planned to run about 18 months to cover the seasonal variation of the epidemics of the causative different viruses.