The Role of Photoacoustic Spectroscopy in Analyzing the Ozone Layer

The ozone layer is important to human civilization because its primary function is protecting us from the ultraviolet (UV) radiation emitted from the sun’s rays, particularly the more dangerous UV-B and UV-C rays. As a result, it is important for scientists to continually monitor the health of the ozone layer.

According to a recent study published in the journal Environments, researchers from the National Institute for Laser, Plasma, and Radiation Physics recently analyzed the health of the ozone layer in their home city of Magurele, Romania (1). By measuring the ozone concentration in three distinct areas of the city, the research team was able to compile a snapshot as to the health of their atmosphere, and what variables are playing heavy roles in influencing the state of it.

Environmental action: world ozone day, need for global efforts to protect ozone layer, understanding its vital role in Earth's ecosystem, encouraging sustainable practices to preserve our environment. Generated with AI. | Image Credit: © Ruslan Batiuk - stock.adobe.com

Ozone is a highly reactive gas comprised of three oxygen molecules (O3) that is present in the Earth’s stratosphere and troposphere (2). Its location determines whether the ozone will affect life on Earth in a negative or positive way. Stratospheric ozone and tropospheric ozone are formed differently. The interaction of solar UV radiation with molecular oxygen helps form stratospheric ozone (O₂ ​+ UV light → 2O → O + O_2​ → O₃​), which shields Earth’s inhabitants from harmful UV radiation (2). Meanwhile, tropospheric ozone is formed from photochemical reactions, and this is what we breathe on Earth. Generally, these reactions are formed between volatile organic compounds (VOCs) and nitrogen oxides (NOx): (NO₂​ + UV light → NO + O → O + O₂​ → O₃​) (2).

In their study, the research studied the tropospheric ozone concentration because recent increases in this type of ozone in urban areas has raised concerns. For the study, three distinct locations within the city of Magurele were selected: a spot within the city (labeled as P1); in a forest nearby (labeled as P2); and in an industrial area (labeled as P3) (1). The study was conducted during the spring and summer seasons, focusing on structural and locational differences.

Ozone measurements were made using a laser spectroscopy system to assess the system’s sensitivity and selectivity (1). This system measured the role of humidity in detecting ozone in the ambient air. The study found that average ozone levels from March to August were 24.45 ± 16.44 ppb for P1 (city), 11.96 ± 3.80 ppb for P2 (forest), and 95.01 ± 37.11 ppb for P3 (industrial area) (1). The researchers found that ozone concentrations were at its highest during the summer, especially in the afternoon (1).

The researchers also sought to capture the diurnal fluctuations; as a result, they collected air samples twice a day during the week when most people are commuting back and forth to work. By conducting diurnal analysis of the air samples, the researchers demonstrated in their study that temperature often influences the higher ozone levels (1). The study also showed that several meteorological factors, such as wind direction and speed, impacted ozone levels in the troposphere (1).

Out of the three locations that were studied, location P2 exhibited the lowest ozone concentration levels. This finding made logical sense, because the location was a forest close to busy roads. As a result, the forested area, which was comprised of trees, had a pollution-reducing capacity that the other locations did not possess (1).

As a result, the laser spectroscopy system effectively quantified ozone in the complex mixture of ambient air. The study also showed the important role of trees in reducing air pollution. Trees perform several key functions on this front. First, they remove pollutants directly from the air (3). Secondly, they reduce the air temperature, which alters the pollution concentration, and finally, they reduce energy consumption in buildings (3).

This study from Romania reinforces the importance of atmospheric health, especially because of the process of climate and weather fluctuations, which is ongoing. The study also adds additional insight about the relationship between ozone levels, human behavior, and meteorological factors (1). Because of this study’s findings, scientists are advancing our knowledge on ozone pollution, and its broader impact on societal activities.

References

(1) Petrus, M.; Popa, C.; Bratu, A.-M. Determination of Ozone Concentration Levels in Urban Environments Using a Laser Spectroscopy System. Environments 2024, 11 (1), 9. DOI: 10.3390/environments11010009

(2) U.S. Environmental Protection Agency, Ozone Pollution and Your Patients’ Health. EPA.gov. Available at: https://www.epa.gov/ozone-pollution-and-your-patients-health/what-ozone (accessed 2024-10-16).

(3) National Park Service, Air Pollution Removal by Urban Forests. NPS.gov. Available at: https://www.nps.gov/articles/000/uerla-trees-air-pollution.htm (accessed 2024-10-16).