To scrub window screens, remove them and vacuum or brush them to eliminate dust. If they need a further cleanse, clean them using a heat, sudsy combine, then rinse and permit them to dry totally. Some mould is usually harmful. In case you have issues about dealing with mould yourself https://dailyspecter.com/achieve-spotless-surfaces-with-pure-water-cleaning-the-ultimate-solution-for-window-and-building-cleaning/