NYC Trees: A Green Paradox - Are They Helping or Hurting Our Air?

NYC's Trees: A Green Paradox - Are They Helping or Hurting Our Air?

New York City's trees are a vital asset, providing shade, absorbing carbon, and contributing to a more beautiful urban landscape. However, a new study reveals a surprising twist: the isoprene emitted by trees, when combined with nitrogen oxides from car and building emissions, can create ground-level ozone, a harmful pollutant.

<figure aria-label="media" role="group"> <img alt="People walking on a foot path in a park with large trees on either side." src="https://static01.nyt.com/images/2024/09/15/multimedia/15CLI-NYC-trees-air-tchj/15CLI-NYC-trees-air-tchj-articleLarge.jpg?quality=75&amp;auto=webp&amp;disable=upscale" srcset="https://static01.nyt.com/images/2024/09/15/multimedia/15CLI-NYC-trees-air-tchj/15CLI-NYC-trees-air-tchj-articleLarge.jpg?quality=75&amp;auto=webp 600w,https://static01.nyt.com/images/2024/09/15/multimedia/15CLI-NYC-trees-air-tchj/15CLI-NYC-trees-air-tchj-jumbo.jpg?quality=75&amp;auto=webp 1024w,https://static01.nyt.com/images/2024/09/15/multimedia/15CLI-NYC-trees-air-tchj/15CLI-NYC-trees-air-tchj-superJumbo.jpg?quality=75&amp;auto=webp 2048w" sizes="((min-width: 600px) and (max-width: 1004px)) 84vw, (min-width: 1005px) 60vw, 100vw" decoding="async" width="600" height="400"> <figcaption> Prospect Park in Brooklyn, which covers more than 500 acres. </figcaption> </figure>

This chemical reaction can negate some of the benefits trees provide, particularly on hot days when isoprene emissions increase. The study suggests planting non- or low-isoprene emitting trees in areas with high nitrogen oxide levels to avoid exacerbating the ozone problem.

However, experts caution against solely focusing on isoprene emissions when selecting tree species. They emphasize that oaks and other shade trees offer numerous advantages, such as managing stormwater, providing wildlife habitat, and mitigating the urban heat island effect.

The study highlights the need for a balanced approach, recognizing the importance of reducing nitrogen oxide emissions from vehicles and buildings to reap the full benefits of urban trees.

<figure aria-label="media" role="group"> <img alt="People sit at outdoor tables under trees in a city park." src="https://static01.nyt.com/images/2024/09/15/multimedia/15CLI-NYC-trees-air-qhtp/15CLI-NYC-trees-air-qhtp-articleLarge.jpg?quality=75&amp;auto=webp&amp;disable=upscale" srcset="https://static01.nyt.com/images/2024/09/15/multimedia/15CLI-NYC-trees-air-qhtp/15CLI-NYC-trees-air-qhtp-articleLarge.jpg?quality=75&amp;auto=webp 600w,https://static01.nyt.com/images/2024/09/15/multimedia/15CLI-NYC-trees-air-qhtp/15CLI-NYC-trees-air-qhtp-jumbo.jpg?quality=75&amp;auto=webp 1024w,https://static01.nyt.com/images/2024/09/15/multimedia/15CLI-NYC-trees-air-qhtp/15CLI-NYC-trees-air-qhtp-superJumbo.jpg?quality=75&amp;auto=webp 2048w" sizes="((min-width: 600px) and (max-width: 1004px)) 84vw, (min-width: 1005px) 60vw, 100vw" decoding="async" loading="lazy"> <figcaption> Union Square in Manhattan. </figcaption> </figure>

Ultimately, the solution lies in a combination of sustainable urban planning, cleaner energy sources, and a smart approach to tree selection that considers both air quality and the broader benefits of our urban forest.