The Impact of Botanical Sources on Air Pollution in Los Angeles

In recent years, California has made significant progress in reducing vehicle emissions through environmental policies and technological advancements. However, a new study has revealed that microscopic airborne particles and ground-level ozone, key contributors to air pollution, have remained stubbornly high due to the rise of ‘secondary sources’ such as trees and shrubs in urban areas.

A team of US researchers conducted a series of aerial surveys over Los Angeles in June 2021 to directly measure volatile organic compounds (VOCs), which are precursors of particulate and ozone pollution emitted by plants. Unlike previous studies that relied on estimates or models, this approach allowed the researchers to measure airborne pollutants in real-time using a mass spectrometer. The results showed that botanical sources of VOCs, including compounds like isoprene and monoterpenes, contributed to a significant portion of secondary organic aerosols in the atmosphere.

Air pollution remains a major health concern globally, with fine particles and ozone in the air posing risks such as heart disease, respiratory illnesses, and increased mortality. VOCs play a crucial role in the formation of these harmful pollutants, making it essential to identify and mitigate sources of VOCs in urban environments. The study highlights the need for better monitoring and regulation of VOC emissions from both industrial and botanical sources.

The researchers observed that botanical emissions of VOCs increase with hot weather and drought conditions, raising concerns about worsening air quality in the summer months. As global temperatures rise, the contribution of botanical sources to air pollution may become more significant. Understanding the factors that influence biogenic VOC emissions, such as temperature and plant species, will be essential in developing effective strategies to combat air pollution.

While urban green spaces are known for their environmental benefits, including cooling effects and improved air quality, they also contribute to VOC emissions through the release of terpenoids. Despite this, reducing green spaces is not the solution, as they provide numerous health benefits and help mitigate the urban heat island effect. Instead, researchers suggest studying the emissions of different plant species and their response to climate change to better manage air pollution.

The findings of the study shed light on the significant impact of botanical sources on air pollution in Los Angeles and emphasize the need for further research and action to address this issue. By understanding the role of plants in VOC emissions and their relationship to climate conditions, policymakers can develop targeted strategies to improve air quality and protect public health. As cities continue to grow and temperatures rise, mitigating the impact of botanical sources on air pollution will be crucial in creating sustainable and healthy urban environments.