Volatile organic compounds (VOCs) are low-boiling point small molecules that are emitted from a variety of sources. Biogenic VOCs (BVOCs) are a class of VOCs that are emitted from biological sources, like trees, plants, soil microbes, and animals (including humans).
These VOCs float around in the air all around us. They’re generally invisible to the eye, but we breathe them in while inside our homes, out on city streets, or under the forest canopy.
They come a wide variety.
We’re beginning to learn how the amount, and variety, of these biogenic VOCs impact human health and ecosystem health.
We’re also beginning to discover that these BVOCs tell a story.
Biogenic VOC emissions can be altered by the health and environmental conditions of the forest, because each individual plant emits these chemicals according to its state of health.
Thus, the concentrations, and varieties, of BOVCs in the air can indicate the health and current conditions of that ecosystem.
But studying this is a big challenge.
Individual plants, even of the same species, emit patterns in slightly different ways.
Different species will emit different BVOC profiles.
And nearby plants respond to the emissions around them, but in varying ways, so the complexity increases pretty quickly.
We’re only just starting to learn about the extent of the information BVOCs provide, but it’s an exciting area of research ripe for investigation.
BVOCs and Human Health
When it comes to forests, the majority of BVOCs come from the isoprenoid family.
These terpenes are emitted from a variety of metabolic processes within trees, plants, and soil microbes.
BVOCs are thought to play a role in the positive effects of forest bathing (shinrin yoku), the Japanese-derived practice of improve physical and mental health through walking through forests and other wild spaces.
Research is still vary nascent in this area, but research is emerging on the health effects of exposure to these chemicals.
Many effects appear to be promising for promoting positive health effects, like:
- antimicrobial effects
- bronchodilation and antispasmodic activities on the respiratory system
- improved quality of sleep
- improved cognitive performance
- antioxidant effects
- reduce the negative effects of toxic exposures
- anti-inflammatory effects
- anti-nausea
Here are some of the more common BVOCs and their impacts.
Alpha-Pinene: Alpha-Pinene, a major component of pine resin, is renowned for its therapeutic benefits. It has anti-inflammatory and bronchodilator effects, making it useful for respiratory health. Inhaling alpha-pinene can reduce inflammation in the airways and promote relaxation, reducing stress and anxiety. These properties make it a common ingredient in aromatherapy and forest bathing practices, where its scent contributes to the calming and restorative effects of spending time in nature
Limonene: Limonene, found in the peels of citrus fruits and many trees, has several health benefits. It acts as an antioxidant and anti-inflammatory agent, which can help reduce oxidative stress and inflammation in the body. Inhaling limonene can also improve mood and cognitive function, providing a sense of well-being and mental clarity. These benefits are particularly evident in practices like forest bathing, where exposure to limonene-rich environments can enhance mental health and boost immune function
Eucalyptol: Eucalyptol, also known as 1,8-cineole, is the primary component of eucalyptus oil. It has been widely used for its anti-inflammatory, analgesic, and mucolytic properties. Eucalyptol can help clear the airways, making it beneficial for respiratory conditions such as asthma and bronchitis. Additionally, its soothing aroma can promote relaxation and reduce stress, contributing to overall mental and physical well-being. Using eucalyptus oil in aromatherapy or forest bathing can harness these benefits, providing a natural way to support respiratory health and reduce anxiety.
Are there any negative effects of forest-derived BVOCs?
Interestingly, some negative effects are also present.
These negative effects, however, are not generally derived from the forest-BVOCs themselves.
Instead, these chemicals interact with human-generated VOCs like sulfur dioxide, nitrous oxides, and ground-level ozone (all generally bad for human health) that come from industrial processes and react with these forest BVOCs to produce secondary aerosols with negative health outcomes.
Isoprene, emitted by vegetation and used in industrial applications, is associated with some of these negative health effects.
Isoprene is a precursor to secondary organic aerosols (SOAs) which have oxidative properties that can influence respiratory health.
Studies have shown that exposure to isoprene-derived SOAs can induce the expression of inflammatory markers such as IL-8 and COX-2 in human lung cells.
This suggests that isoprene could contribute to oxidative stress and inflammation in the respiratory system.
Yet, isoprene is one of the primary forest BVOCs, and forest bathing still routinely produces net positive health benefits.
Therefore, the overall benefits in inhaling the variety of these forest-derived BVOCs is generally positive.
Furthermore, the further you are from industry-derived air pollution, the more likely these negative SOAs are at low levels.
What Can We Learn From Biogenic VOC Emissions?
It’s not just human health.
The research on biogenic VOC emissions is still early, and therefore we are still along way from understanding the full extent of what they can tell us.
But here are a few things that science is starting to uncover.
Biogenic VOCs May Provide an Early Warning Sign for Infections and Disease
Humans and wildlife aren’t the only ones who can get sick.
Trees and plants routinely get infected, and in some cases, these diseases are infectious and can spread to wipe out huge populations of infected species.
As the plant fights these diseases, the profile of biogenic VOC emissions appears to change in variety of diseases.
These BVOC profiles appear to be plant-specific, disease-specific, and even specific to the severity and length of infection.
As we learn more about how to quantify and analyze these Biogenic VOC emission profiles, we may be able to improve forest management practices with activities like:
- Spotting diseases earlier to prevent infectious spreading throughout agricultural lands or wild lands
- Monitoring the effects of interventions to restore health
- Identifying asymptomatic, infected species to prevent spread or introduction of diseases to new areas
Biogenic VOCs May Provide a Window into the Hidden Life of Forest Ecosystems
Human health and forest management are very “practical” reasons to study BVOC profiles.
But there are reasons to study biogenic VOC emissions for reasons that, at least for the moment, are simply tied to expanding science and our understanding of life on Earth.
A wonderful book by Zoë Schlanger, called The Light Eaters: How the Unseen World of Plant Intelligence Offers a New Understanding of Life on Earth, does a masterful job of telling the story of the latest research in this area.
Here, we learn that airborne plant chemicals act as a means of communication between plants.
BVOC profiles may change according to the plants’ desire to attract or repel certain insects or animals, as well as other environmental conditions.
In essence, learning more about the BVOC profiles floating around us is likely an entire world of information and activity we are almost fully blind to.
Discovering and learning more about this activity will help us uncover just a bit more of the magic of the forests.
It may be a long shot, but it may even lead to better conservation practices.
In the world of animal science, learning more about their intelligence helps can lead to a better global perception of the need to protect them.
- Increased Empathy and Ethical Considerations: Understanding that animals are intelligent beings with complex behaviors, emotions, and social structures can foster empathy and ethical considerations. People are more likely to advocate for the protection of animals when they recognize their cognitive abilities and the similarities between human and animal experiences.
- Scientific Evidence and Awareness: Scientific research on animal intelligence provides concrete evidence of their capabilities. This information can be disseminated through media, educational programs, and conservation campaigns, raising awareness about the intrinsic value of animals beyond their ecological roles.
- Influence on Policy and Legislation: Greater knowledge about animal intelligence can influence policymakers and legislators to create and enforce laws that protect animal rights and welfare. This can lead to stricter regulations against practices that harm animals, such as poaching, habitat destruction, and unethical treatment in captivity.
- Cultural and Societal Shifts: As societies learn more about animal intelligence, cultural attitudes can shift towards more compassionate and sustainable practices. This can result in changes in consumer behavior, such as reducing demand for products that harm animals and supporting eco-friendly and cruelty-free alternatives.
- Conservation Efforts and Funding: Increased understanding of animal intelligence can boost support for conservation efforts. People may be more willing to donate to or participate in initiatives aimed at preserving habitats and protecting endangered species when they appreciate the complexity and significance of animal lives.
Overall, learning about animal intelligence highlights the need for ethical treatment and conservation, fostering a global perception that values and prioritizes the protection of animals.
In the same way, perhaps plant intelligence research may help shift our view of forest protection, and understanding biogenic VOC emissions has become a key part of that endeavor.