Opponents of storing petcoke, a sooty byproduct, on Chicago’s Southeast Side can breathe easier now that Beemsterboer Slag Corp. has announced it’s leaving the city for greener (for now) pastures, following public pressure from the city and angry neighbors. The Koch Brothers typically set (read: buy) trends rather than follow them, so don’t expect their petcoke business KCBX to hoist anchor anytime soon, but enviros can celebrate this development, even if the city’s new regulations give companies a full two years to cover their dusty piles of petcoke.