Get that brolly out! It may feel deeply counter-intuitive - but rainy days could offer a host of health and mood-lifting benefits. Rain improves air quality, literally washing fine particulate pollution away, and rainfall also releases Geosmin, a fragrant compound which is linked with relaxation and increased serotonin levels. What’s more, Professor Michael Terman, from Columbia University in New York, introduces Michael to negative air ions created after rainfall. He is researching how high levels of negative ions could potentially reduce stress, stave off depression and maybe even boost your immune system. Meanwhile, our volunteer Dennis steps outside and embraces the rain. New episodes will be released on Wednesdays, but if you’re in the UK, listen to new episodes, a week early, first on BBC Sounds: bbc.in/3zqa6BB Producer: Nija Dalal-Small Science Producer: Catherine Wyler Assistant Producer: Gulnar Mimaroglu Trainee Assistant Producer: Toni Arenyeka Executive Producer:: Zoe Heron A BBC Studios production for BBC Sounds / BBC Radio 4.