A lot of those consumers are buying air and water purifiers.

Two years ago the American market research firm Freedonia Group said in a report that China's demand for filters would grow 13.5% every year to 66.2 billion yuan ($10.8 billion) by 2014. Much of that would come from filters for vehicles and factories, the report said, but filters for home or office use are no hot air.

"As income levels grow, more people in China will be able to afford home water and air purification equipment, and rising demand for higher quality and extended life filters are likely to boost overall market value," the Freedonia Group's report says. "The demand for filters in consumer and other markets will be fueled by increasing personal income levels and rising concerns about air and water quality."

It's hard to find a purifier seller who doesn't know that. A year ago, as Louie Cheng tells it, the purifier mass market was dominated by Alen Air, Blueair and IQAir. Then everyone else figured out the market was huge and buyers willing to pay up to 20,000 yuan ($3,252) for a piece of equipment. That glut has people wheezing all the harder. "The market has become confused," Cheng says. "There's too much data. Everyone says they can remove 99% of pollution."

Among an estimated 3,000 sellers of water purifiers in China are Panasonic ( PCRFY) and Philips ( PHG). Panasonic seeks sales growth in China from 8.5 billion yen ($87.6 million) in fiscal 2011 to 25 billion yen in fiscal 2015. Philips has positioned itself since 2007 as a health care champion in China including as it works with the government to find out what people need.

You can't say it's all because of purifiers, but Panasonic's share prices rose 65% since a trough in November and Philips stock has grown 45% over the past year. Yet dirty water can't be bogging them down. In 2011, Chinese families bought 20 million water purification systems, the official China Daily newspaper online reports.

On the clean air side, Honeywell ( HON) sells purifiers in China, and they sit at the top of the company's China website for home appliances. Honeywell has invested $1 billion in China, where it employs 12,000 people and has subsidiaries or joint ventures in 20 cities. Its share prices have gone up 47% over the past year.

A top competitor is Sharp ( SHCAY), which also banners air purifiers high on its China webpage, dubbing them "protective spirits" and claiming world sales to date of 40 million units. Sharp's Nasdaq share prices are down from a year ago but up 137% over a past-year low in October. It must be something in the air.

At the time of publication the author had no position in any of the stocks mentioned.

This article was written by an independent contributor, separate from TheStreet's regular news coverage.

If you liked this article you might like

Sign of the Times -- Hitachi Looks to Block Chinese Rivals on U.S. Soil

Cramer: Under Trump, These Are Probably Done Deals

Cramer: Northrop-Orbital Deal Is Bigger Than Just the Synergies

Honeywell Relocating Global Retail HQ to Massachusetts

First Leg Down of United Tech; Hurricanes -- Jim Cramer's Top Thoughts