A man threatening to smash his 27-inch iMac outside an Apple outlet on Shanghai's Middle Huaihai Road was soon asked to come into the store accompanied by 10 police officers.

Zou Hongqing demonstrates in front of an Apple outlet in Shanghai on Thursday. Zou demanded a refund after purchasing what he claimed was a defective product from the tech giant. [Photo by Yong Kai / for China Daily]

"I told them I need a refund, and they owe Chinese users an apology," the man, Zou Hongqing, told China Daily.

Zou said his computer developed dust spots because of defective design and should be recalled.

He said he arrived in Shanghai six days ago to sue Best Buy, an authorized distributor of Apple.

Shanghai's Xuhui District Court will mediate between Zou and Best Buy on March 20.

Apple declined to comment on the incident, but had said earlier that the problem was caused by the dust in the air in China, rather than being a quality or design flaw, provoking outrage among users nationwide.

Zou, a 45-year-old photographer, bought the computer in September 2010. After one year of use, he discovered a lot of dust on the LCD display that severely blurred the view.

"The dust is somehow inside the panel. You simply cannot get to it by removing the glass," he said.

Zou then contacted Best Buy and Apple, asking for replacement or repair. But Apple's stance is the warranty he bought does not cover dust and that his situation is a stand-alone case.

"But how is that possible? I run air purifiers in my home. This has to be a design flaw or defect," Zou said.

A manual on Apple's website advises users not to operate the computer in areas with airborne dust, smoke or fireplaces. Otherwise, "tiny airborne particles may, in rare instances, enter the ventilation openings of your iMac and under certain circumstance result in a slight haze on the inside surface".

To protect his rights and gather more evidence, Zou founded an online chat room that attracted more than 100 iMac consumers in similar situations.

One user has spent thousands of yuan replacing four screens, but the dust problem still lingers.

"As a world-class computer manufacturer, how could Apple shift the problem onto others and ignore its own defects?" asked an angry user.

A woman surnamed Wang said that when she spotted the dust and called the after-sales hotline, technicians told her it was due to an inappropriate environment, including moisture, room temperature, household dust or even pet hair.

"I personally consider this a design flaw and it doesn't happen to everyone. But there are enough cases to make it a concern," she told China Daily.

A poll conducted by information technology portal pcpop.com in December showed that 74 percent of iMac users surveyed encounter dust problems, while 84 percent said the problem does not occur on computers from other manufacturers.

iMac's dust problem is not unique to China. Many American and European buyers have to tackle the dust problem and they complain online that Apple won't cover the expenses for changing displays.

On Apple's websites, there are a number of clients complaining about the dust issue. A user named Ginnin from Moscow said the Apple service in Moscow attributed her dust spot problem largely to environmental causes, and another buyer from California said he had to pay $600 to fix the display.

Contact the writer at hewei@chinadaily.com.cn