Hong Kong people are breathing in up to 10 times more cancer-causing pollutants than their counterparts in Japanese cities, tests show. The first trial tests of the airborne pollutants - produced by diesel engines - indicate 'alarming' levels compared with elsewhere, government chemists say. Trials carried out to determine the need for a full-scale study found the most dangerous pollutants in levels about 10 times greater than in Japan and nearly 3,000 times greater than in Denmark. The results have triggered the government purchase of a $4-million mass spectrometer machine to carry out more detailed long-term tests. Hong Kong was unable to carry out tests in the past as each of the thousands of samples had to be processed abroad at a cost of $8,000. Chemists can run their own tests with the new machine, though assistant government chemist Chan Chi-kin said extra staff were needed as preparing each sample would take two to three days. Senior chemist Au-yeung Chi-yuen said five air samples from the Eastern Harbour Tunnel during one week last summer showed nitropyrene levels up to 11 nanograms per cubic metre of air. A similar study in a busy traffic area in the Japanese city of Kanazawa found levels up to 1.15, while in rural Europe they reached just 0.004 nanograms per cubic metre. Mr Chan said the results were 'alarming' and more studies were needed. Government chemists are awaiting approval to use the mass spectrometer to carry out the first study of notoriously dangerous dioxins - chlorine-containing chemicals which build up in the body and attack various organs and the immune system. Dioxins are produced during combustion, particularly by incinerators. Three years ago, the Environmental Protection Department warned that hospital incinerators spewing out black smoke were probably breaking strict regulations on dioxin emissions, but no studies were done because equipment was unavailable.