Cutting-edge air quality monitoring strengthens public health nationwide

The fires that devastated many in Los Angeles in January 2025 not only scarred the landscape but also changed the air.

A day after the Eaton fire burned through Altadena, California, chlorine levels in the atmosphere reached approximately 40 times the normal amount, while lead peaked at over 100 times the usual level. Atmospheric chlorine can cause respiratory irritation and distress; lead can cause damage to the brain and central nervous system.

"The Los Angeles fires burned homes and cars, which contain electronics, plastics and other synthetic materials that can give off toxic chemicals when they burn," said Nga Lee "Sally" Ng, a professor at Georgia Tech.

Ng leads the U.S. National Science Foundation-supported Atmospheric Science and Chemistry mEasurement NeTwork (ASCENT), which includes 12 air quality measurement sites nationwide. Each site has state-of-the-art instruments that help us understand aerosols, or tiny particles in the atmosphere. The network is constantly analyzing the chemical constituents of aerosols with a diameter smaller than 2.5 micrometers, referred to as PM_2.5, which contribute to more than 90% of the adverse health impacts associated with air pollution.

Researchers in the ASCENT team analyzed data from three locations across Southern California during and after the fire to reveal that certain aerosols carried a unique chemical signature associated with burning synthetic materials in urban fires.

"We now have a very powerful magnifying glass to see what aerosols are entering the atmosphere and how those aerosols change as they travel across the landscape," Ng said.

A few months ago, in late September 2024, Ng and her team analyzed ASCENT data following a fire that broke out at the Conyers chemical plant in Georgia's Rockdale County. The instruments showed a sharp rise in chlorine- and organic-containing aerosols associated with the chemical fire, although the PM_2.5 levels did not rise above U.S. Environmental Protection Agency standards. The team was able to track those aerosols as they traveled to the Atlanta metro area and differentiate them from Atlanta's usual aerosols.

"We provide ASCENT data to the public in real time so that people know what's in the air we're breathing," Ng said.