Border Lemons: Biosensors for Air Pollution

San Ysidro, CA is a border town situated between San Diego, USA and Tijuana, Mexico. As the most heavily trafficked port of entry in the western hemisphere, communities that live near the area experience excessive air pollution from vehicles idling at the border, and face significantly higher respiratory diseases in comparison to San Diego County. This new project explores the potential of citrus fruit as publicly accessible biomonitors for local air pollution. 

Why?

As a research fellow for the UC San Diego Cross-Border Initiative,  I learned about a study done by San Diego State University on air quality in partnership with the Environmental Protection Agency (EPA). I attended their public exhibition and learned that San Ysidro, a border town situated between San Diego and Tijuana, Mexico, is the most heavily trafficked port of entry in the Western hemisphere. Communities that live near the area experience excessive air pollution from vehicles idling at the border, and face significantly higher rates of respiratory disease.

I decided to produce a documentary on the community members in San Ysidro throughout the summer of 2017. One of the community members I interviewed mentioned to me that his backyard citrus fruit tress collected black spots only where exposed to air. I brought his polluted lemons to my faculty mentors at the UC San Diego Center for Microbiome Innovation,  and with support of the community, we decided to explore the potential of citrus fruit as low-cost and publicly accessible biosensors.

Documentary film segment showing San Ysidro community member Guillermo Cornejo and his thoughts about local air quality and his backyard citrus fruit.

Current + future work

Current work includes working with the Rob Knight Lab and Pieter Dorrestein Lab to better understand the potential ability of citrus fruit to sequester air pollutants through the GlobalFoodOmics project—a project that uses metabolomics and metagenomics to investigate the molecules and bacteria in everyday food and drink. I am also working with community members to discuss the applications of this work to the San Ysidro community and collectively ideate about using citrus fruit as accessible visible indicators for air quality in San Ysidro. Other future directions with this project include involving local children in middle and high school to partake in a citizen science project that allows them to better understand the issues that impact their home community.