Trees Protect Lungs

The Powerful Link Between Urban Greenery and Respiratory Health

Respiratory illnesses—including asthma, chronic obstructive pulmonary disease (COPD), and respiratory infections—are on the rise in many communities, driven by air pollution, heat, and environmental stress. While public health solutions often focus on medicine and technology, a natural and highly effective intervention is frequently overlooked: trees. Extensive scientific research shows that urban trees are vital to cleaner air, healthier lungs, and lower rates of respiratory disease.

🌿 Trees Filter Harmful Pollutants From the Air We Breathe

Air pollution is one of the leading contributors to respiratory illness. Fine particulate matter (PM2.5), nitrogen dioxide (NO₂), and ground-level ozone inflame lung tissue, trigger asthma, and increase the risk of infections and long-term lung damage.

Urban trees act as living air filters:

• Leaves and needles capture PM2.5, preventing particles from entering the lungs (Nowak et al., 2014).

• Tree canopies absorb NO₂ and ozone, improving overall air quality (Nowak & Greenfield, 2018).

• Cooling provided by trees helps reduce the formation of ground-level ozone, a major asthma trigger (The Nature Conservancy, 2016).

According to the U.S. Forest Service, urban trees in the United States remove approximately 17 million tons of air pollutants annually, providing billions of dollars in health benefits (Nowak & Greenfield, 2018).

🫁 Trees Reduce Asthma and Improve Lung Function

Studies show that communities with more tree canopy experience better respiratory health outcomes, especially among children and older adults.

• A study in The Lancet Planetary Health found that increased tree cover significantly reduced childhood asthma rates in urban neighborhoods (Donovan et al., 2019).

• Tree-lined streets are associated with lower asthma emergency room visits, especially during heat and pollution spikes (Lovasi et al., 2008).

• Long-term exposure to greener environments improves lung development in children and reduces bronchitis symptoms (Markevych et al., 2017).

These benefits are strongest in low-income communities, where air pollution exposure is typically highest and tree canopy lowest—making trees a powerful tool for environmental health equity.

🌬️ Trees Support People with Chronic Respiratory Conditions

For individuals living with asthma, COPD, lung cancer, or post-viral respiratory damage (including COVID-19), trees provide meaningful support for lung health and comfort.

Trees and green spaces:

• Reduce inflammation-triggering pollutants that worsen COPD and asthma

• Create cooler, shaded environments that ease breathing in hot weather

• Lower stress—an often overlooked asthma trigger—through exposure to nature (Wolf et al., 2020)

Research from the University of Washington shows that time spent in natural settings improves breathing comfort, reduces anxiety, and can enhance immune response (Wolf et al., 2020).

🔥 Protecting Lungs During Wildfire Smoke Events

Wildfire smoke is now one of the most dangerous sources of respiratory harm in the Western U.S. While trees cannot stop smoke, they help reduce long-term exposure by filtering particulates and creating localized “cleaner air zones” in neighborhoods and parks.

Combined with cooling effects, this helps vulnerable populations—especially seniors—avoid heat-smoke health risks, which are significantly higher when both hazards occur at once.

🧒 Equity: Planting Trees Where Respiratory Illness Hits Hardest

Low-canopy neighborhoods—often historically redlined or under-resourced—have higher air pollution, more asthma hospitalizations, and poorer lung health (American Forests, 2021). Planting and protecting trees in these areas is a direct public-health action that reduces disease and improves quality of life.

🌱 A Natural Prescription for Healthier Lungs

Trees are not merely decorative—they are a frontline public health tool against respiratory illness. Planting and maintaining tree canopy:

• Reduces pollution exposure that damages lungs

• Prevents asthma attacks and respiratory disease

• Protects children, seniors, and vulnerable residents

• Saves healthcare costs and improves quality of life

As health professionals increasingly advocate “nature prescriptions” for respiratory health, expanding tree canopy becomes a clear, evidence-based strategy for healthier communities.

Protecting our lungs starts with protecting our trees.

References (APA 7th Edition)

American Forests. (2021). Tree Equity Score: Analysis of urban tree canopy and socio-economic disparities. https://www.americanforests.org/our-programs/tree-equity-score/

Donovan, G. H., Gatziolis, D., Longley, I., & Douwes, J. (2019). Vegetation diversity protects against childhood asthma: Results from a large New Zealand birth cohort. The Lancet Planetary Health, 3(2), e64–e71. https://doi.org/10.1016/S2542-5196(18)30267-6

Lovasi, G. S., Quinn, J. W., Neckerman, K. M., Perzanowski, M. S., & Rundle, A. (2008). Children living in areas with more street trees have lower prevalence of asthma. Journal of Epidemiology & Community Health, 62(7), 647–649. https://doi.org/10.1136/jech.2007.071894

Markevych, I., Schoierer, J., Hartig, T., et al. (2017). Exploring pathways linking greenspace to health: Theoretical and methodological guidance. Environmental Research, 158, 301–317. https://doi.org/10.1016/j.envres.2017.05.030

Nowak, D. J., Hirabayashi, S., Bodine, A., & Hoehn, R. (2014). Modeled PM2.5 removal by trees in ten U.S. cities and associated health effects. Environmental Pollution, 193, 119–129. https://doi.org/10.1016/j.envpol.2014.05.035

Nowak, D. J., & Greenfield, E. J. (2018). U.S. urban forest statistics, values, and projections. Journal of Forestry, 116(2), 164–177. https://doi.org/10.1093/jofore/fvx004

The Nature Conservancy. (2016). Planting healthy air: A global analysis of the role of urban trees in addressing particulate matter pollution and extreme heat. https://www.nature.org

Wolf, K. L., Lam, S. T., McKeen, J. K., Richardson, G., van den Bosch, M., & Bardekjian, A. (2020). Urban trees and human health: A scoping review. International Journal of Environmental Research and Public Health, 17(12), 4371. https://doi.org/10.3390/ijerph17124371