It is perhaps worth noting this from Daily Telegraph - May 28 2009 //Police sirens should be used only when "absolutely necessary" because the sound can make areas seem "more dangerous", according to Sir Paul Stephenson, the chief of the Metropolitan Police. "Is there something we can do to reduce our contribution to the cacophony of noise in London? Because I do live in London and listen at night to all the sirens." He also said paramedics and firefighters must also bear responsibility for their contribution to the "cacophony".// - http://tinyurl.com/pz9j49