Bianca Pamela Aridjis-Olivos, a graduate student in aerosol and atmospheric chemistry at Texas A&M University will present her team’s results at the fall meeting of the American Chemical Society (ACS). ACS Fall 2025 is being held Aug. 17-21; it features about 9,000 presentations on a range of science topics.
In 2023, as intense heat raged across Texas, Aridjis-Olivos started working with faculty mentor Renyi Zhang and colleagues in the Center for Atmospheric Chemistry and the Environment (CACE) at Texas A&M. Because heat waves are predicted to worsen across the U.S. in the next few years, the CACE team was motivated to determine how extreme heat impacts atmospheric chemistry and air quality.
The researchers designed and conducted a pilot study of atmospheric chemistry during Texas’ August 2024 heat wave. They collected air samples throughout the day and night from Aug. 5 to Sept. 3 on the university campus in College Station, TX, where temperatures ranged from 90 to 106 degrees Fahrenheit (32 to 41 degrees Celsius). Additionally, the air sampling occurred when there were no wildfires nearby, isolating the effects of the heat wave itself without the influence of wildfire smoke on air quality.
The researchers analyzed air samples for pollutants of public health concern, including nitrogen oxides, ozone, volatile organic compounds (VOCs) and nanoparticles. For this work, they used a suite of sensitive instruments to detect trace gases and measure aerosol properties, including a proton transfer reaction time-of-flight mass spectrometer (PTR-ToF-4000).
“You can think of it like a super sensitive nose,” explained Aridjis-Olivos, adding that the PTR-ToF-4000 sniffs for VOCs then “gently marks them so they could be identified and weighed in real time.”
Results showed concerning levels of ozone, oxygenated VOCs and acid-rich nanoparticles that increased in concentration with outdoor temperatures. The researchers also observed increased levels of airborne pollutants created by sunlight-fueled chemical reactions in the air. Notably, they discovered that, during heat waves, trees release more natural VOC emissions, including isoprene, a precursor to ozone, that could be harmful in heavily wooded places, such as College Station.
“It really was surprising, how these emissions from trees increase during heat waves and interact with air pollution,” says Aridjis-Olivos, referring to the region’s ample oak trees. “On their own, the trees’ emissions aren’t dangerous. It’s when they react with other emissions under strong solar radiation that we get elevated ozone and secondary organic aerosols that are dangerous for the public health.”
The researchers are currently analyzing additional data from their August 2024 fieldwork. In the meantime, they share recommendations for keeping safe during heat waves:
Stay indoors during peak sunlight hours (typically noon to 4 p.m.), when temperatures and ozone levels are highest. Avoid exercising or commuting near major roadways or urban hot spots during extreme heat. Keep an eye on the local air quality index and adjust outdoor plans accordingly, when possible. Keep windows closed to limit exposure to outdoor air pollutants. While these tips can help in the short-term, the researchers say real progress depends on understanding how climate change affects atmospheric chemistry and air quality so scientists can better predict pollutant formation and protect public health.
The research was funded by Texas A&M University’s vice president of research, ASCEND seed grant initiative, and the Center for Atmospheric Chemistry and the Environment.
Visit the ACS Fall 2025 program to learn more about this presentation, “Measuring gas-phase air pollutants during heatwave conditions” and other science presentations.
###
The American Chemical Society (ACS) is a nonprofit organization founded in 1876 and chartered by the U.S. Congress. ACS is committed to improving all lives through the transforming power of chemistry. Its mission is to advance scientific knowledge, empower a global community and champion scientific integrity, and its vision is a world built on science. The Society is a global leader in promoting excellence in science education and providing access to chemistry-related information and research through its multiple research solutions, peer-reviewed journals, scientific conferences, e-books and weekly news periodical Chemical & Engineering News. ACS journals are among the most cited, most trusted and most read within the scientific literature; however, ACS itself does not conduct chemical research. As a leader in scientific information solutions, its CAS division partners with global innovators to accelerate breakthroughs by curating, connecting and analyzing the world’s scientific knowledge. ACS’ main offices are in Washington, D.C., and Columbus, Ohio.
To automatically receive press releases from the American Chemical Society, contact newsroom@acs.org.
Note to journalists: Please report that this research was presented at a meeting of the American Chemical Society. ACS does not conduct research, but publishes and publicizes peer-reviewed scientific studies.
Follow us: Facebook | LinkedIn | Instagram
Title
Measuring gas-phase air pollutants during heatwave conditions
Abstract
Climate change and air pollution are two interconnecting environmental crises that confront humankind in the 21st century and are closely tied to the variations in atmospheric compositions. Since pre-industrial times, rising greenhouse gases and aerosol levels have disrupted the Earth’s radiative balance, altered geochemical cycles, and impacted air quality and health. However, gas-to-particle conversion and changes in gas-phase composition remain poorly understood, as these interconnected atmospheric physicochemical processes continue to challenge efforts to predict future climate. The record-breaking 2023 heat waves in the southern U.S. highlight the urgent need to understand how extreme heat affects atmospheric chemistry, particularly NOx, O3, volatile organic compounds (VOCs), and secondary organic aerosols (SOAs). Recognizing this critical gap, a pilot field campaign program was developed and conducted in August 2024 in College Station, Texas, bringing together multiple research groups from the Center for Atmospheric Chemistry and the Environment (CACE) at Texas A&M. An Ionicon proton transfer reaction time-of-flight mass spectrometer (PTR-ToF-4000), equipped with selective reagent ion sources (SRI), enables detailed gas-phase analysis of VOCs and their aerosol formation potential under heatwave conditions. Additionally, concurrent measurements of O3 and NOx provide insight into photochemical processes under extreme heat conditions, both of which are discussed in this presentation. This study aims to improve air quality management strategies and inform public health responses by deepening our understanding of the interactions between heatwaves, VOC emissions, and pollutant formation, ultimately contributing to enhanced preparedness and mitigation efforts.
END