"Guanzhou, China – Every night, columns of hulking blue and red trucks invade China’s major cities with a reverberating roar of engines and dark clouds of diesel exhaust so thick that it dims headlights.

"By daybreak in this sprawling metropolis in southeastern China, residents near thoroughfares who leave their windows open find their faces stiff with a layer of diesel soot.

"Trucks are the mules of this country’s spectacularly expanding economy – ubiquitous and essential, but highly noxious.

"Trucks here burn diesel fuel contaminated with more than 120 times the pollution-causing sulfur that the US allows in most diesel. While car sales in China are growing even faster than truck sales, trucks are by far the largest source of street-level pollution.

"Tiny particles of sulfur-laden soot penetrate deep into residents’ lungs, interfering with the absorption of oxygen. Nitrogen oxides from truck exhaust, which build all night because cities limit truck traffic by day, bind each morning with gasoline fumes from China’s car fleet to form dense smog that inflames lungs and can cause coughing and asthma.

"The ten million trucks on Chinese roads, more than a quarter of all vehicles in this country, and a major reason that China accounts for half the world’s. Sating their thirst helped push the increase in oil consumption, and oil prices to nearly $100 a barrel, before a recent decline, and has propelled China as the world’s largest emitter of global warming gases.

"Yet cleaning up the truck pollution presents complex problems. For instance, regulators have begun raising emission standards for new trucks, but have left millions of older ones belching black smoke. Forcing businesses and farmers to buy more expensive vehicles could put a drag on the economy, which already faces inflationary pressures from rising food prices and other costs.

"The fear of inflation – not to mention political and social unrest – has led Beijing to prevent the country’s mostly state-owned oil companies from increasing diesel prices at the pump in pace with global oil prices. Raising fuel prices for farmers, whose incomes have lagged behind those of city-dwellers and who need diesel for their tractors, is one concern. Lower diesel prices also essentially subsidize every manufacturer in China’s export machine.

But price controls create a vicious circle. Oil giants like Sinopec, losing money on every gallon of diesel they refine because of the low sale prices, upgrade refineries slowly, if at all. And they seek out cheap crude which has high levels of sulfur.

"Low diesel prices frequently make trucks more cost-effective than trains which pollute less. Sales of large freight trucks in China outpace those in the US. Demand for diesel at service stations is so great, and supplies of it are so tight, that rationing and shortages of diesel have become common. Truck drivers idle for hours only to be allowed as little as five gallons of fuel.

"This has created myriad problems from gridlock that chokes China’s cities to hundreds of thousands of premature deaths from heart and lung problems, according to the World Bank.

"American regulators have labeled diesel soot a likely carcinogen. A growing body of academic literature blames tiny airborne particles from diesel exhaust, coal-fired power plants and other sources for up to 90% of all deaths from outdoor air pollution, because the particles penetrate so deeply into lungs. Diesel engines also emit large quantities of nitrogen oxides, which react with gasoline fumes to produce photochemical smog when hit by sunlight.

"Mainland Chinese atmospheric scientists concluded in an analysis in the Journal of Environmental Sciences that, here in Guangzhou, particles were the pollutant farthest out of line by the widest margin with air quality norms 226 days a year.

"New tests by Chinese and American researchers in Tianjin in northeastern China found that diesel engines in trucks and buses accounted for 93% of all nitrogen oxides in China and 97% of all particles.

"Sulfur clogs emissions control equipment. And China lacks an effective control equipment, and the more advanced the equipment, the more vulnerable it is to sulfur damage. Truck drivers tend to fill up in rural areas with less expensive, high-sulfur fuel.

"Two dozen truckers said in interviews in Guanzhou and in Shenzhen that fuel shortages had become chronic, with trucks idling for hours as they wait in line."

– from Economic Reform, January 2008