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Quantifying the environmental benefits of using urban greenery to remove particulate matter (PM 2.5 and PM10)

South Central Los Angeles, California

Featured image for the project, Quantifying the environmental benefits of using urban greenery to remove particulate matter (PM 2.5 and PM10)

Typical South Central Home and Yard (Image courtesy of Grey4Green)


The Challenge

South Central, Los Angeles, is a region of Southern Los Angeles County, California, encompassing 28 distinctive bedroom neighborhoods stretching from Watts and Compton to Crenshaw and Inglewood. It is not intercity urban, but instead the area has a significant volume of owner-occupied single-family homes with yards.  Historically South Central encompasses a large number of blue-collar workers of multiple races and ethnicities. The area has been known for redlining and its national role in both civil rights and civil unrest movements since the early 50s. South Central is indicative of other injustices regarding quality to life and environmental issues within disadvantaged urban bedroom communities nationally and globally.

Several communities within South Central LA, such as Watts, Compton, and Glenwood, lie along the Alameda Corridor, a railway which connects over 65 miles of track between downtown LA to Long Beach. The area is also crisscrossed by multiple 10 lane freeways, the 105 East to West, and 710 & 110 North to South.  Air pollution has been an issue in this area of Los Angeles County for several decades with high ozone and particulate matter (PM) 2.5 levels. Now, climate change is compounding the issue with extreme urban heat. All these factors are known for the increase in air borne diseases (asthma & bronchitis), heat stroke and heart disease, and most recently vulnerability to COVID-19. Creating an economic model in South Central to quantify the removal of PM 2.5 and PM 10 would serve as a significant basis for replication in other disadvantaged communities grappling with these issues across the country and globe.

Several community projects over the decades have made little progress in addressing air pollution, urban heat island effect, or food insecurity. The investment models for improving our urban centers are broken and show no signs of creative change or ability to scale under increasing climate change condition, or even worse, under a national pandemic crisis.

The Project

Watts Towers

Grey4Green is interested in working with a scientist and neighborhoods in South Central in a 6×6 block quadrants to reduce PM 2.5 / 10 with continuous regenerative plant foliage. The ideal mixture of plants may include multi-purpose specimens, such as shade trees for reduced urban heat island effect and fruit trees to improve food nutrition. The objective is to economically quantify the multiple environmental benefits of a repeatable community plant palate.

The project’s impact theory is that a multi-purpose community plant palate can energize and  compound multiple stakeholders’ investments into a repeatable community investment model, by reducing the cost to each stakeholder’s investment and amplifying the results for each dollar invested.

The project breaks down the individual social justice silo investments and rebuilds the social justice investment into a crowdfunding project with multiple desirable and measurable outputs. This project is a continuation from a 2019 Watt’s micro-climate project, that demonstrated that economically disadvantaged communities want to participate in mitigating climate change and just require the knowledge and tool set to do so.



The project is estimated to take 18 months to begin February 2021 with the following major milestones during the duration of work with Thriving Earth Exchange:

  • Drawing up a plan of action for the area of focus
  • Getting neighborhood investment and quantifying available information
  • Partnering with health department, air quality board and Cal-Trans for quantifiable investable metrics goals.
  • Partnering with urban landscape designers and architects
  • Partner with plant nurseries for targeted plant material
  • Partner with EPA, NOAA and NSF for development funds
  • Develop a social media plan

Project Team

Community Leads

Joseph Gallegos is leading the charge to develop new economic models that drive urban eco island developments. Mr. Gallegos is a serial entrepreneur  – problems are just opportunities for new solutions. At Grey4Green there are two sides of the company. The commercial side focuses on teaching Do It Yourself (DIY) homeowners on how to grow lush landscapes with greywater. Then there is the Public Good side of the company, where we focus on empower disadvantage communities to become self-sufficient  in solving multiple community issues with plants. These could include increase nutrition food gardens, food security with nuts and fruit trees, RX Agriculture to solve diabetic conditions, and using trees to mitigate urban heat island, air pollution, and particulate matter 2.5 pollution.  We empower homeowners by showing them how to start trees and vegetable crops by seed, what trees provided food and shade, and what trees can provided extra income by selling the fruits or nuts.


Co-community leader and Grey4 Green Community Outreach Director Dylan Mendoza was the lead on the 2019 Watt’s project and developed much of the direct engagement with homeowners on the project. Dylan will be a key element in the direct community outreach on this project as he has been in previous Watts and Compton microclimate projects Mr. Mendoza is engineering student interested in the intersection of sustainable urban centers that mimic nature “Biomimicry”.  Interested in the holistic benefits of natural plants on community health.  He brings his plant knowledge and teaching skill set, directly to the homeowner. Mr. Mendoza will spend whatever it takes answering homeowners’ questions about the benefits and negatives of growing trees for shade and food.


Community Science Fellow

Sehdia Mansaray is a Master’s in Development Practice student at the University of Arizona. Her interests, grounded in understanding human-environment linkages, identity, and power to address food security, conservation, and community resilience, have directed her towards field work in environmental anthropology, geography, and agroforestry in Guatemala, Reunion Island, and Senegal. She is currently an Outreach Associate at the USA-National Phenology Network where she is partnered with the Arizona Association for Environmental Education and Arizona Master Naturalist Association to create more inclusive and equitable natural history programming in Tucson, AZ. She has a B.S. in Environmental Science, B.A. in Anthropology, and French minor from North Carolina State University. In her free time she gardens, plays guitar, dances, hangs out with family and friends, and binges mystery shows.

Community Scientist

Samira Muhammad is a Ph.D. student in the Laboratory of Environmental and Urban Ecology at the University of Antwerp, Belgium. Samira also has a M.Sc. in Geographical Information Science from Lund University, Sweden. Her current research focuses on the reduction of atmospheric particulate matter (PM) using urban plants. Samira’s recent Journal publications mainly focus on the importance of leaf traits in accumulation and immobilization of atmospheric PM. Samira has used a wide array of analytical methods for estimating PM on leaves of urban plants including gravimetric analyses, magnetic analyses and scanning electron microscopy. Besides, Samira has expertise in analyzing leaf traits such as trichome density, leaf wettability and stomatal density using either knowledge-based procedures or image analysis. In her free time Samira loves to bake, eat and spend time with family and friends.

Collaborating Organization(s)


This project is supported by funding from the Gordon and Betty Moore Foundation.