The Day After Tomorrow is a silly movie that wastes Dennis Quaid, one of my favorite actors. (The illustration is from the movie's official home page.

But the scientific principles that underlie it are sound, and here's the proof.

A team from the University of Maryland tested air over the areas affected by last year's blackout, and found huge differences in the level of pollutants.

Sulphur dioxide levels decreased by 90 per cent, there was around half the amount of ozone and visibility increased by 40 kilometres.

What this means is not just that we're killing ourselves, but that the fix, if it comes, will have a huge impact very quickly. The disaster, in other words, may be overdone, but the recovery could be as dramatic as anything Hollywood can imagine. (That's Quaid again, in a 1978 role he'd rather we forget.)

Our family is going to test this hypothesis next month.

Both my teenage kids now have pollution-induced asthma. They have grown up in the pollution-filled air of Atlanta, Georgia, a city that has insisted upon coal fire and auto transport come hell or high water.

Both use inhalers regularly. They use them before they exercise. My son's inhaler is new, so he's still using it several times each day.

But next month they go to camp in Wyoming. They will breathe relatively clean air for a few weeks, and get lots of exercise. They're going to have a lot of fun. I envy them.

And when they get back they will, for a time, need their inhalers less often.

My family is not unusual. Your family suffers, too. Look at the car in your garage, and look at your children tonight.

Which is more precious?