New Air-Cleaning Tech Uses X-Rays to Fight Airborne Pathogens

A new type of air-cleaning technology that uses X-ray irradiation could contribute to better protect human lungs from allergens, airborne viruses and ultrafine particles in the air. Washington University engineering researchers developed and tested a device they call SXC ESP, which they expect could help to prevent respiratory and viral infections and inhalation-induced allergic reactions more efficiently than existing filter-based systems.

“Because many people in developed countries spend the majority of time indoors, properly maintaining indoor air quality is an absolute necessity to protect public health,” said Prof. Pratim Biswas, who led the recent study of the device, published in Applied and Environmental Microbiology.

Asthma, the chronic respiratory disease that can be triggered by inhaling allergens, pollen, pet dander and other particles, is actually one of the most costly health-care expenses in the United States at more than $50 billion.

By incorporating a novel corono-soft X-ray enhanced electrostatic precipitation technology, the researchers were able to ensure very efficient charging of the particles over a broad range of sizes and their capture in the SXC ESP, instead of just removing larger particles from the airflow as current devices employing electrostatic charging do. Difficult-to-charge particles are readily charged and trapped in the electrical field. An even bigger advantage is that due to the high ion concentrations and an oxidizing environment, organic pathogens are disintegrated to carbon dioxide. Also, a nanostructured catalyst coating can destroy toxic particles.

“Traditional air cleaners can trap viruses or other toxic particles in the filter, where they linger and grow,” Biswas says. “This device finds the virus or toxic particle or bioterror agent and inactivates it in one application.”

The scientists exposed mice with compromised immune systems to the downstream air stream passing through the unit that contacted infectious viruses, allergens, anthrax, smallpox and other particles in the air. The sensitive mice survived, indicating that the SXC ESP was very effective in removing these biological agents from the air.

Ultimately, this technology could be incorporated into stand-alone air cleaners or scaled for use in aircraft cabins, offices and residential HVAC systems. It also could be used to clean up a diesel engine or power plant exhaust.

A startup, Aerosol Control Technologies (ACT), that is based on the patented process Biswas developed was already founded, with the two founders Michael Gidding and Daniel Garcia currently working on a prototype to be tested as a diesel particulate filter substitute.

There are many applications for the technology in the coal industry, Gidding says, from dust control and safety at the mine to flue-gas treatment at the power plant.

Study:
Kettleson E, Schriewer J, Buller M, Biswas P. "Soft X-ray Enhanced Electrostatic Precipitation for Protection against Inhalable Allergens, Ultrafine Particles and Microbial Infections." Applied and Environmental Microbiology. February 2013.