Associate professor of materials science and engineering at Stanford Yi Cui has developed a new air filter material that could be used to help residents of heavily polluted cities breathe more easily.

Cui was inspired to develop this material after traveling to China for business, where he noticed the suffocating smog and pollution.

Because Cui’s work normally focuses on battery technology rather than air quality products, he and his students didn’t immediately turn to conventional air filter materials. Instead, they looked for polymers that would have a strong attraction to particle matters smaller than 2.5 microns. These particles are the main components in smog and pose the greatest risk to human respiratory and overall health.

Cui and his team eventually landed on polyacrylonitrile (PAN), a material commonly used to make surgical gloves.

The researchers then used a process called electrospinning to convert liquid PAN into extremely thin fibers — roughly one thousandth the diameter of a human hair.

The resulting material allows for about 70 percent transparency while collecting 99 percent of the particles.

The high transparency of this material makes it a promising candidate for use in window screens and personal facemasks. It could also potentially be used to filter exhaust from cars or industrial smoke stacks.

Although further testing is needed to determine if the material could withstand the acidic or otherwise toxic compounds in these types of heavy exhaust, Cui and his team have determined that the material can collect up to 10 times its own weight and could last for about a week.

Contact Allegra Clara McComb at amccomb ‘at’ stanford.edu.