Small-sized air quality monitors on the rise

Leo Jin, 33, recently jumped on a growing trend. He bought a portable air quality monitor to test the air in his home, office, and car, in a move to combat his increasing discontent with pollution. Not only did he want a mask and an air purifier, but he was determined to know whether his expensive purifier worked.

But, now, he's not sure whether he should trust his monitor's results.

Based on an educated guess when comparing the monitor's readings before and after he turned on his air purifier, Jin said he thought the monitor could very well be "reliable and sensitive to changes in air quality". Yet, Jin said he still has his doubts about the data, namely because it comes from a small device that only costs a few hundred yuan. To clear up this uncertainty, Jin is considering buying a different brand of air quality monitor, possibly a foreign one, to compare data between the two devices.

But it is not necessarily about the air quality monitor's origins, it is about its size and cost, according to Song Guangsheng, secretary general of the China Indoor Environmental Monitoring Committee.

The prices of the devices vary in accordance with the accuracy of the sensor used in the monitor, Song said. Those sensors usually use laser technology in determining the size and number of the particles in the air, which is a quite complicated process.

"The accuracy and sensitivity [of small-sized devices] won't be as reliable as the larger equipment that costs more than hundreds of thousands of yuan, which are usually used for things like scientific research," he said.

But the smaller and cheaper air quality monitors are valuable and more than adequate for families to use as a reference in daily life, he said.

"It's helpful when you use it to see how the data changes before and after using a purifier and to see the differences between outdoor and indoor air quality," he said.

Addressing concerns some domestic consumers have about the accuracy of, specifically, domestic devices, Song said China has better technology due to a market for air quality monitors that has been flourishing over the past few years.

One only needs to search on China's biggest online retailer, taobao.com, to confirm that China's air quality monitor market is, indeed, flourishing. Key words "PM2.5" and "detector" yield thousands of results, with popular products including a 299-yuan ($48.67) monitor from domestic electrical appliance firm, Haier, and a 749-yuan detector by another Chinese electronics manufacturer, Hanvon.

However, according to experts, the market for the domestic air quality monitors is still in its infancy, lacking set national product standards, making it inevitable that quality vary greatly among brands.

Most manufacturers have their monitors sent to testing centers to calculate their percentage of error, and this range from brand to brand is between 10 and 20 percent, according to an anonymous expert in the industry quoted by the Guangzhou Daily last October.

Knowing little about the technology behind the devices, consumers like 26-year-old white collar worker Li Qiaochu still choose to trust their domestic air quality monitors. When Li found out she was pregnant in September, she immediately purchased a 400-yuan monitoring device that measures PM2.5 particles and formaldehyde. The alarming figures on the monitor pushed Li to buy an air purifier.

"It's very useful," said Li, who added that the sensitivity of her device is fine and can read real-time changes in data. She has used the device both at home and at work, and her relatives also have borrowed the device several times.

"I just hope the data will continue to be accurate," she said.

Song suggested that people should only buy devices that have a third party test report and replace their device every six months to guarantee its accuracy.