Christmas for me is a nostalgic time, filled with magical childhood memories of knee-deep snow, Santa Claus, family gatherings, jingle bells and air pollution.

Beijing at this time of year brings back all the holiday warmth I experienced so long ago in the United States. The distinctive odor of burning coal on a biting winter morning here is comfortable and familiar, like meeting an old friend after a long separation.

Inhale. Exhale. Inhale. Exhale. Ahh, the Yuletide joy!

Every Christmas in my childhood, we set off to Grandmother's house, where I would rummage around in her coal bin for the biggest lumps of anthracite I could find to burn in her immense fireplace. That's the cleanest coal, though nobody noticed or cared.

Experts say smells trigger strong associations in the brain, and I think that's true. My father would stoke the fire and teach me about coal and coke. And I'd reverently watch the lumps glow red as I breathed in the toxic stuff of Christmas memory, mingled with the aroma of freshly baked cakes and cookies.

Most other people were burning identical coal in similar fireplaces, and the whole town was wrapped in dingy gray. This was before anybody knew about PM2.5 - a time when the government was still conducting atomic bomb tests in the atmosphere. In those halcyon days, health hazards were relegated to the back burner.

What mattered most to me was that Santa Claus would soon slide down the chimney with a bag of toys.

This was in Utah, one of the rectangular states, with towering mountains rising on all sides of our small community. At the center of the valley was a freshwater lake whose shores were graced by a steel plant, put up in the latter days of World War II.

That might seem an odd place for a factory serving shipyards - about 900 kilometers from the Pacific Coast. But rich iron ore and coal deposits were nearby. Plus, it made strategic sense: The plant was so far inland that it was beyond the reach any possible Japanese air attack.

Coal and coke were used to fire the furnaces, and the ore was transformed into slabs of steel for US warships. For nearly 50 years after the war, the plant served commercial markets.

Seen from the foothills, its smokestacks loomed like immense, leafless trees, belching a lovely shade of dirty orange - the jetsam of industry, which at that time meant prosperity. The odor was omnipresent.

Nobody worried that it was killing us. All we knew was that our eyes burned a little now and then, especially around Christmastime.

The steel plant closed a decade ago, and the land is now being prepared for a high-tech park, with retail shops and residences. The air is clean. But still I have my Christmas memories, which have been rekindled here in China. They're a gift to be thankful for.

Red alert on air pollution? Bah! What is that compared with holiday cheer? Truly, I feel at home. Merry Christmas!