We seldom see face masks worn in public any more, but a new study suggests people in certain parts of the country can still benefit against seasonal toxic blooms of algae. University of Miami researchers say face masks filter out over ninety percent of toxin particles while high-efficiency air conditioning filters were also effective in reducing airborne algae toxins. Their experiment was specifically designed to measure effectiveness against harmful algae, but masks and high quality air conditioner filters may also help protect against other airborne allergens, The study appears in the journal Aerosol and Air Quality Research and suggests harmful algae events are expected to become more common because of climate change.