Bright, sunny days are ideal for airing the mattress as sunlight kills dust mites and its UV rays have antimicrobial properties. The mattress is stripped of bedding and vaccuumed clean. If possible, it is taken outside and propped up where it can air in direct sunlight for 2-6 hours. It can alternatively be leaned against a wall indoors with the room’s windows thrown open, if it is too difficult to take it outside. Afterwards it is returned to the bed and made up with newly washed sheets. This semi-annual task helps the bed stay clean and fresh.