Air pollution is a pressing global issue that contributes to numerous premature deaths each year. One of the primary culprits is particulate matter known as PM2.5, which consists of airborne particles with a diameter smaller than 2.5 micrometers. Among the various constituents of PM2.5, organic aerosols stand out as the dominant component. These organic aerosols have long perplexed scientists due to their chemical complexity, making it challenging to assess their toxicity. However, a groundbreaking study led by researchers at the Georgia Institute of Technology sheds new light on the chemical composition and harmful effects of these organic aerosols, emphasizing the threatening impact they pose to human health.
Published in Environmental Science and Technology, the study conducted by the Georgia Tech team reveals that oxidized organic aerosols (OOA) are the most toxic type of organic aerosols found in PM2.5. OOA are also the most prevalent form of organic aerosols globally. Professor Nga Lee (Sally) Ng, who holds positions in both Georgia Tech’s School of Chemical and Biomolecular Engineering and School of Earth and Atmospheric Sciences, explains that OOA is generated when wildfire smoke interacts with the atmosphere. To analyze the composition of PM2.5 in Atlanta, Georgia, the researchers employed advanced techniques like mass spectrometry. Simultaneously, they also measured the production of reactive oxygen species (ROS) in alveolar cells, which are cells present in the lungs. ROS are molecules that induce oxidative stress and cell damage, leading to various health issues, including cardiopulmonary diseases. By using cellular assays, the team was able to identify highly unsaturated species within OOA that are major contributors to ROS production, further enhancing our understanding of the chemical features that make organic aerosols toxic.
In recent decades, the contribution of fossil-fuel sources to the formation of organic aerosols in the United States has declined due to reduction strategies. Consequently, other sources, such as biomass burning, have become more prominent in the creation of OOA. Fobang Liu, the lead author of the study, notes that biomass burning, including wildfires, is expected to play a significant role in the production of OOA. Biomass burning aerosols contain a high fraction of oxygenated aromatic compounds, making them particularly toxic. Liu emphasizes that this research highlights the increasing threat of organic aerosols in the future.
The findings of this study underscore the importance of interdisciplinary collaboration in addressing the global air pollution crisis. The fields of atmospheric chemistry, toxicology, epidemiology, and biotechnology must join forces to develop effective strategies to mitigate the health impacts of PM2.5. Professor Ng emphasizes that understanding the sources and chemical processing of organic aerosols, particularly secondary organic aerosols, is essential in formulating these strategies. Different regions may have varying types of organic aerosols due to diverse emission sources and atmospheric conditions. Thus, long-term measurements of organic aerosol types across geographical areas are crucial for a comprehensive understanding of their health impacts.
The research conducted by the Georgia Tech team provides valuable insights into the chemical composition and toxicity of organic aerosols found in PM2.5. By identifying oxidized organic aerosols as the most harmful type, the study highlights the growing threat of air pollution to human health. As the sources of organic aerosols change, it becomes imperative to collaborate across scientific fields to develop effective mitigation strategies. Only through continued research and collective efforts can we combat the global air pollution crisis and protect the well-being of our planet and its inhabitants.