Infection expert shares why you should air pillows and bedding outside in a heatwave — and when (and how hot) to machine wash them to kill dust mites and fungi

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Each day during a heatwave, my neighbor hangs her pillows and bedding on the line for a few hours of ‘sun washing’ or ‘sun curing’ – a viral cleaning trend that claims leaving bed sheets in direct, super-hot sunlight UV-sanitizes them. I understand the appeal – this ‘CleanTok’ hack is free, and who doesn’t like sleeping in line-fresh bedding?But here’s the microbiological truth: ‘sun washing’ does little to get fungi, bacteria, dust mites and odors out of your pillows, bed sheets and toppers. According to a study on optimal ways to remove dust mites, allergens and pollen, a standard machine wash at 104°F 40°C leaves 94% of dust mites alive and kicking in your bedding. Yep, 94%.So why is my neighbor dead-set on ‘sun washing’ her bedding during a heatwave? “The real benefit is moisture and not disinfection,” says Dr. Shanina C. Knighton, PhD, RN, CIC, an infection prevention expert and Research Associate Professor at the Frances Payne Bolton School of Nursing at Case Western Reserve University.To help us separate cleaning myth from microbiological reality, Dr. Knighton explains what ‘sun washing’ actually achieves, why pillows and bedding become moisture bombs during heatwaves, and the exact temperature a washing machine needs to get rid of the nasties.