Blundell has been active on environmental issues, first as Chair of the Planning Committee of the Oxford City Council (1970–73), during the time when it stopped the building of a motorway through the city centre, pedestrianised much of the historic centre, and made North Oxford a conservation area. From 1998 to 2005 he was Chair of the Royal Commission on Environmental Pollution, when he oversaw the production of key reports such as those on "Energy – the Changing Climate", "Chemicals in Products – Safeguarding the Environment and Human Health", and "Turning the Tide: Addressing the Impact of Fisheries on the Marine Environment". He is a Distinguished Member of Humanists UK.