The event, according to the website, "promotes a 'clean commute' and is part of the region's Clean Commute Initiative, which begins in April. Late spring is the start of the ground-level ozone season, when we hear about Code Red and Orange Ozone Action Days. On those days, the air is dangerous to breathe - especially for the young and for the elderly. Single-occupancy vehicles produce dangerous ozone-emission pollution in the Baltimore area. Bike commuting can improve the air we breathe."