Some people call me a Great Wall expert, others an adventurer, a researcher or a photographer. I am not sure which is the most accurate. But for certain, after leading many campaigns to pick up litter on the Wall, I am the most famous foreign garbage collector in China.

Editor's note: Great Wall expert William Lindesay is sending back postcards from his latest exploration of the Wall. Another postcard will arrive next Friday.

Taking this long road along the Wall there is one undeniable negative change from 20 years ago - the arrival of garbage.

Beside expressways, main trunk routes, quiet mountain roads - even remote tracks across the desert - we have seen garbage everywhere. Nowhere is sacred from this modern attack.

When I walked along the Wall in 1987 the garbage problem had not even begun. Nobody spent what little cash they had on bottled drinks or snack foods. Shops did not have plastic bags. Food was wrapped in pre-cut rectangles of crisp brown and biodegradable paper.

With wealth has come waste, and with a throw away mentality waste has become an eyesore, environmental menace and, in the Wall's case, a sad indication of peoples' disrespect for this vast outdoor museum.

On this 20th anniversary Jeep safari, we have been practicing what we preach. The basic aim of the "Countryside Code" promoted by the International Friends of the Great Wall is to encourage people to take their own trash home.

After camping we leave nothing but footprints. At the end of a day on the road, the garbage we have generated gets dumped in the hotel bin.

Before setting off from Beijing I decided that en route we should begin another long journey in promoting a "Green Driver's Code". I see garbage thrown out of car windows in Beijing. I have noticed how taxi drivers clean their vehicles while waiting for a fare. Truck drivers do the same while stuck in traffic jams. All ends up beside or even right on the road. Why?

William Lindesay's wife, Wu Qi, and son, Thomas, help promote the "Green Driver's Code" at Jiayuguan, Gansu province. Piao Tiejun

While people will not tolerate their own spaces being littered, most do not care about public space. The reality is that with the Olympic Games just around the corner, most of China - outside of city centres - is littered with garbage.

Before leaving Jiayuguan we distributed in-car garbage bags to drivers we met in the main parking lot at the famous fortress. Made from recycled plastic material, these are washable and reusable, and have some suggestions printed to advise how every driver can play their own part in helping to make China more beautiful.

I was exhausted after distributing 200 bags, introducing myself, shaking hands and asking for everyone's participation. But I was encouraged by everyone's happiness and pledges.

Driving west towards Dunhuang, I saw more of the wild desert scenery and ecology that faces the threat of despoliation by drivers' littering. And I remembered what Chairman Mao Zedong once said: "A journey of a ten thousand li begins with a single step."

(China Daily January 25, 2008)