As the COVID-19 pandemic has grown, you will probably have seen photos and video of workers in protective gear using high-pressure sprays to sanitise city streets. Spain has even taken the radical step of spraying bleach on beaches. You may have asked yourself if this really makes much difference to the risk of coronavirus transmission. If not, why would governments expend time, energy and dollars doing it?
Based on our knowledge of the conditions required for disinfectants to work, we suspect these activities are as much about authorities being seen to do something as about actually stopping the spread of COVID-19.