An heritage bridge in Kolkata, India, may not last much longer as its longevity is threatened by a tide of human saliva. The Howrah Bridge, a relic of the British colonial era, is used by 500,000 pedestrians and an equal number of vehicles to cross the Hooghly River every day. But for more than 70 years, pedestrians have spat half-chewed betel leaf, areca nut and slaked lime on its steel hangers, corroding the structures support fixtures. The spitting has become such a menace that “the hanger bases have reduced to 50% of their original size in just three years”, ML Meena, Chairman of Kolkata Port Trust, told the BBC. After efforts to curb spitting through spot fines failed, engineers have suggested a fibreglass coating be placed on the 78 hangers to save the bridge from decay.