That IS a nice little touch (2 + 18). I'm left with 7 down unparsed. A stratospherically bad environmental issue. O?O?E ?O?E is easy to solve but where does it come from?
Re 2 + 18, 24 belongs there too, no? Qaos (almost) always has a ‘ghost’ theme.This puzzle is no exception. Look harder at some of the other solutions!