The filthy, black grime crusting city buildings and statues isn’t just an eyesore. It’s also an unlikely contributor to lung-searing smog, according to Canadian scientists.
Pollution from cars, factories, and other sources can waft around until settling on surfaces as grime. Locked into this solid-looking state, it’s easy to assume it doesn’t do much after that until somebody power-washes it into oblivion. But according to James Donaldson at the University of