Dust covering the Chinese city is harder than steel

Pollution researchers examined air quality in Xi'an City and found a bad situation of dust and smoke covering the city.

According to the South China Morning Post (SCMP), residents living in one of the most polluted cities in China are breathing and dust particles are harder than iron and steel.

Xi'an is one of the cities with the largest amount of dust and smoke in China.

But health experts say that the size of new dust particles directly affects human health, not hardness.

A group of scientists at Jiaotong University in Xi'an collected samples of haze around the city, in northwestern Shaanxi Province.

Xi'an City has about 8.7 million people and is one of the worst air pollution areas. This city ranked 374 out of 387 cities last year to monitor air quality.

'We want to find out what these dust particles form from,' said Liu Boyu, a researcher. 'We want to study the hardness of dust particles separately'.

They found many components of dust everywhere in the city, including chromium, iron, aluminum and lead. The researchers also found that dust particles of different shapes, with round beads like balls, had particles of other shapes.

Qin Shihuang's terracotta army in Xi'an.

But what surprised the researchers was the hardness of the dust particles, according to Liu.

About 70% of dust particles are so hard that they can wear out industrial equipment made from alloys.'The dust particles are so hard that they will cause damage to super-precision machines , ' Liu said.

Liu and colleagues published the study last week, after five years of thorough research. But the hardness of dust is not the main cause affecting human health.

'The severity of dust lies in how deep they penetrate the body and their size , ' said Zhang Xin, from the respiratory department at Shanghai Zhongshan Hospital.

'The smaller the dust particles, the easier it is to get into the lungs, making it difficult for them to dry and almost impossible to remove them from the body.'

Xi'an government is still struggling to find ways to fight huge dust and smoke. This is worrisome because the city is associated with many important events in history, including its find.