What a day! Clean Air Day 2017 trended at 1 on UK twitter for 5 hours, reaching 38million people! On 15 June, Clean Air Day caused a buzz across the UK. Thousands of people got involved in schools, businesses, hospitals and communities - making pledges, going car free and raising awareness of air pollution. With our Thunderclap alone, we reached 3.4 million people with our air quality message. Here are some of our favourite tweets, photos and stories from the day: [View the story "National Clean Air Day" on Storify] Thank you to everyone who helped to make Clean Air Day such a success!