Shop assistant Nicky Simpson, 20, was desperately fanning her two-year-old daughter Mya who had collapsed on her lap as they travelled towards Chiswick. She said: "This is just unbearable. The windows are open but they don't make any difference. When it's stuck in traffic it is worst. The air just doesn't move, it's completely stagnant. My daughter conked out as soon as we got on. Surely it wouldn't be that difficult to install air conditioning?"