Yes, paxboy, another example of airports being lumbered with the consequences of problems they haven't caused. The air quality problem around Heathrow is primarily a M4/M25 issue.
It's pretty irresponsible of Stewart Wingate (Gatwick's CEO) to latch gleefully onto this. Just wait until someone suggests lumbering GAL with the cost of upgrading the London-Brighton rail line, expansion of M23/M25 etc. People in glass houses shouldn't throw stones.
Regrettably all airports are vulnerable to such arguments. It's akin to the archetypal American lawyer, who always looks to sue the person with the deepest pockets rather than the most culpable.