University unveils new air purifier technology

Chineseresearchers have developed a new technology to clean up indoor air pollution that avoids secondarypollution that existing air purification products in the market can create ifused improperly.

The new airpurifier, developed by a research team from the School of MechanicalEngineering at Shanghai Jiao Tong University, removes indoor pollutants fromair through physical and chemical methods.

ProfessorShangguan Wenfeng, who led the research project, said at a news conference onMonday that current air purifiers clean the air mainly by absorption andfiltering, but this technique has problems.

“For example,the filter needs to be replaced regularly because it will easily reach thesaturation point, which might lead to further pollution,” he said.

Also, while somemachines cannot filter smaller pollutants well, the school’s new technologyovercomes that shortcoming, he said.

The newtechnology removes indoor pollutants through high-voltage electrostatic andcatalytic purification.

Theelectrostatics process the PM2.5 — airborne particles smaller than 2.5micrometers that can go deep into the lungs — and other air pollutants fromoutdoors.

During thisprocess, volatile organic compounds and a small amount of ozone are produced.The second, catalysis module transforms these harmful organic compounds andozone into harmless carbon dioxide and water.

A test wasconducted during the news conference. Because Shanghai air quality wasclassified as “good” at the time, researchers made a smoggy indoor environmentin a 30-square-meter room by lighting six cigarettes. The PM2.5 reading soonreached 700 micrograms per cubic meter, far exceeding the index limit level of500.

When the machinewas switched on, the particles in the room gradually disappeared, with thereading less than 100 within an hour.

Anotherinnovation of the air purifier is that it allows air circulation betweenindoors and outdoors. Indoor air is circulated with outside air through aventilation pipe at the bottom of the machine.

“Even in heavysmoggy weather, the indoor air will continue circulating and be cleaned. Thistechnology is not available in existing machines on the market,” Shangguansaid.

Yang Xin, anenvironmental expert at Fudan University, expressed optimism about theinvention.

“In recentyears, air cleaners have become more and more popular among residents. Awell-designed air purifier will undoubtedly play an important role in improvingair quality,” he said.

Poor air qualityhas been heatedly discussed by the public recently as smog enveloped manycities in autumn and winter. PM2.5 has become the country’s primary polluterand also the main source of indoor air pollution.

In Beijing,the average PM2.5 reading in 2013 was more than double the national standard,according to a Beijing Environmental Protection Bureau report earlier thismonth.

On average,heavy air pollution occurred every six or seven days in the city, said ZhangDawei, director of the Beijing Environmental Monitoring Center.

Shanghai, a citywhose air was once considered clean, saw its Air Quality Index reach nearly 500on Dec 6. An index reading over 300 is considered “hazardous”, the highest in asix-tier rating system of air quality.

Persistent smogacross the country has prompted a surge in sales of dust masks and aircleaners. Sales of air-cleaning machines in 2013 increased 420 percentyear-on-year, according to JD.com, China’s e-commerce giant.

“So far, thistechnology is very developed, and it has already been awarded a patent. We are now looking formanufacturers to help bring this product to market,” Shangguan said.

The researchteam said the retail price of the new air purifier would be competitive withsimilar machines on the market from big international brands like Blueair,Daikin, Philips and Siemens. The price is expected to be 3,000yuan ($496) to 6,000 yuan depending on the size of the room it’s used for.