Babbage: Cleaning the air

<p>The World Health Organisation recently declared that <a href="https://www.economist.com/graphic-detail/2021/02/25/fossil-fuels-may-be-responsible-for-twice-as-many-deaths-as-first-thought?utm_campaign=babbage&amp;utm_medium=podcast&amp;utm_source=third-party-host&amp;utm_content=show-notes" rel="noopener noreferrer" target="_blank">air pollution</a> is the greatest environmental <a href="https://www.economist.com/the-economist-explains/2019/11/02/how-air-pollution-can-ruin-schoolchildrens-lives?utm_campaign=babbage&amp;utm_medium=podcast&amp;utm_source=third-party-host&amp;utm_content=show-notes" rel="noopener noreferrer" target="_blank">threat to health</a> globally. What do cities and governments need to do to <a href="https://www.economist.com/graphic-detail/2020/09/05/air-pollution-is-returning-to-pre-covid-levels?utm_campaign=babbage&amp;utm_medium=podcast&amp;utm_source=third-party-host&amp;utm_content=show-notes" rel="noopener noreferrer" target="_blank">clean up their act</a>? Also, we explore how Occam’s razor, ​​a theory from a medieval theologist, has influenced science. And, could music be an effective way to <a href="https://www.economist.com/babbage/2013/02/07/postcards-from-the-edge?utm_campaign=babbage&amp;utm_medium=podcast&amp;utm_source=third-party-host&amp;utm_content=show-notes" rel="noopener noreferrer" target="_blank">communicate with extraterrestrials</a>? Alok Jha hosts&nbsp;</p><p><br></p><p>For full access to The Economist’s print, digital and audio editions subscribe at <a href="http://www.economist.com/podcastoffer?utm_campaign=babbage&amp;utm_medium=podcast&amp;utm_source=third-party-host&amp;utm_content=show-notes" rel="noopener noreferrer" target="_blank">economist.com/podcastoffer</a> and sign up for our new weekly science newsletter at <a href="http://www.economist.com/simplyscience?utm_campaign=babbage&amp;utm_medium=podcast&amp;utm_source=third-party-host&amp;utm_content=show-notes" rel="noopener noreferrer" target="_blank">economist.com/simplyscience</a>.</p><p><br></p><p>T