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Vol. 53-1 Waste

February 27, 2023


From Red Lines to Tall Pines: Roadside Vegetation Buffers as an Environmental Justice Strategy

In January 2021, President Biden signed Executive Order 14008, which “created the first-ever White House Environmental Justice Advisory Council.”[1] In doing so, the Biden Administration brought renewed attention to a decades-old question: What is the most effective way to address the government’s continued mismanagement of land, air, and water in low-income communities and communities of color?[2] To date, thirteen states have also taken steps to establish offices and commissions with an eye toward pursuing environmental justice.[3]

While conversations about environmental justice are many and varied, pollution is a central theme. It has become increasingly clear that low-income communities and communities of color are disproportionately exposed to the harmful effects of environmental pollution.[4] What’s worse, this phenomenon was no accident—officials have repeatedly approved permits to locate facilities with major sources of pollution in Black and low-income neighborhoods.[5] In many cities, noisy and polluted highways stand as monuments to these historic injustices, and the surrounding residents are still forced live with the consequences of past siting decisions.[6] As state and federal officials show a renewed interest in finding ways to advance environmental justice initiatives, they could do worse than to focus their efforts on addressing roadside pollution.

The Human Cost of Living Near a Highway

The adverse impacts of roadway pollution on human health are well-documented.[7] This article’s scope is limited to the risks and harms of living in close proximity to the poor air quality and noise pollution that highways create in heavily populated areas.

Individuals who live and work close to a busy roadway are at a higher risk of developing illnesses related to air pollution exposure.[8] Our highways are designed to carry a high volume of traffic, and most of those cars are still burning fossil fuels and pumping exhaust into the air. Data from a 2020 study shows that transportation contributes to 27% of the greenhouse gas emissions in the U.S., and light-duty vehicles are responsible for over half of these transportation emissions.[9] Among those emissions, ozone, nitrous oxide, and a whole class of chemicals known as mobile-source air toxics (MSATs) have been measured in high concentrations within an area of up to 500m (approximately 1/3 mile) of a roadway.[10] Particulate matter is also of great concern because it is another byproduct of traffic that can impair respiratory function.[11] The presence of these chemicals as ambient air pollution correlates with increased frequency of cardiovascular and respiratory disease, impaired lung function, and overall mortality.[12] Studies have found that majority-White neighborhoods are associated with less ambient air pollution exposure than majority-Hispanic neighborhoods.[13] A wealth of data also suggests that communities of color are also generally more likely to be located near highways than White communities.[14] If the task at hand is to address the environmental factors that disproportionately impact certain communities, taking steps to clean up the air they’re breathing is a great place to start.

Noise pollution presents a separate set of risks and challenges for those who live within earshot of a major roadway. The constant whir of cars and trucks rushing past, during all hours of the day and night, is first and foremost an annoyance. But as our understanding of the effects of elevated noise levels advances, we are beginning to see that there may also be health risks associated with noise pollution; for example, research has linked noise pollution to an increased incidence of heart attacks.[15] Noise pollution has also been linked to sleep disruption, decreased academic performance, and even shortened life expectancies for those who live close to the source.[16]

Roadside Vegetation Buffers as a Multi-Purpose Mitigation Measure

A variety of technologies and strategies have been proposed and implemented to combat the harmful impacts of vehicular traffic through urban areas, including air filtration, noise-reduction walls, and even plans to move entire highways underground.[17] While they are effective and certainly valuable tools to utilize as we seek to remedy environmental injustices, they are often expensive and can take years to implement.[18] Such mitigation strategies pose a major disruption to the lives and routines of the very people who are supposed to benefit from them.[19] It is therefore essential that we look for ways to mitigate these harms quickly and effectively. The installation and expansion of roadside vegetation buffers (RVBs) has emerged as a promising option and should be leaned on more heavily as a means for making incremental progress toward environmental equity.

In recent years, as the effects of living with vehicular air pollution have become better understood, a number of studies have concluded that plants and trees are some of the most effective tools for cleaning up the mess that cars leave behind. It is important to consider certain species-specific characteristics; deciduous trees, which lose their leaves in fall and winter, are not as effective when their branches are bare. Therefore, there is a preference toward coniferous trees whose efficacy does not respond to the seasons.[20] Additionally, the effectiveness of a given RVB setup in clearing pollutants from the air is largely determined by the height and density (or thickness) of the vegetation buffer.[21] Taller vegetation tends to force polluted air upward, rather than directly outward from the roadway; once at a higher altitude, the pollutants are more easily dispersed to a lower concentration.[22]

While the height of a barrier serves to reduce the concentration of pollutants through dispersion, the goal of density is to reduce pollution by directly filtering the air.[23] Plants consume carbon dioxide through photosynthesis, and their porous surfaces allow them to pull some other toxic compounds out of the air as it passes through them.[24] Certain kinds of vegetation can store airborne chemicals permanently, while others act more as a physical filter for particulate matter by providing an adherent surface that particles can temporarily stick to before being washed into the soil or blown away by the wind during a storm.[25] The effect of these mechanisms is to reduce the amount of pollution in the air while it is close to the road, so that it is less heavily contaminated when it flows outward and reaches the lungs of people living nearby.

Considering height and density together allows for a high degree of flexibility in the design of an RVB, so that it can be optimized to meet the needs of a given location by combining taller plants like trees with shorter, denser shrubs.[26] The EPA’s research into RVB design is ongoing, but it has found that when properly implemented, a combination vegetation buffer can reduce particle pollution by up to 50%, and other pollution by as much as 30%.[27]

Insulation from the high levels of noise that highways produce is another important consideration in reducing the harm of highways on our communities. This has been traditionally accomplished by erecting walls as sound barriers between roadways and residential properties.[28] In addition to their ability to clean the air, RVBs show promise as another way to fight noise pollution: “If it is high enough, wide enough, and dense enough that it cannot be seen through,” roadside vegetation is capable of reducing traffic noise by half.[29] It may not always be feasible to introduce enough tree coverage to achieve that level of noise reduction, but in such instances vegetation can be combined with man-made sound barriers in order to reap the benefits of both sound reduction and air filtration.[30]

There may be no more elegant of a solution to the problem of traffic pollution than the introduction and/or expansion of RVBs. Trees, shrubs, and other vegetation are highly effective at removing pollution from the air, and certain plants can also provide insulation to dampen traffic noise. RVBs are cheaper and can be installed more quickly than some of the more advanced technologies emerging today, and in situations where those more intensive solutions are already being considered, RVBs can serve as an intermediary mitigation step to begin improving conditions immediately until those next steps are implemented.[31] To write them off as a stop-gap measure would be a mistake, however, because nothing could be farther from the truth. In fact, perhaps the greatest strength of RVBs as a mitigation strategy, particularly when held up against technological solutions, is that they will never be rendered obsolete. As electric cars become increasingly commonplace, and traffic no longer necessitates harmful emissions, the trees will continue to improve and beautify the spaces they occupy.[32]

Increased vegetation provides a wide array of additional benefits to a community as well, from the visual appeal of more greenery to relief from the “heat island effect.”[33] And in addition to reducing pollution and acting as carbon sinks, long stretches of vegetation along our urban corridors also provide refuge for local wildlife and act as a habitat for woodland bird populations.[34] Runoff pollution from road surfaces is beyond the scope of this article, but it is worth noting that the soil in RVBs acts as a natural filter, trapping some potentially toxic compounds close to the roadway and preventing them from leaching into local watersheds.[35]

NEPA’s Role in the Path Forward

Since the National Environmental Policy Act (NEPA) became law on January 1, 1970, federal agencies have been required to consider the environmental impacts of the projects they pursue and the decisions they make.[36] On February 11, 1994, President Clinton signed Executive Order 12898 which further directs each agency to “make achieving environmental justice part of its mission by identifying and addressing, as appropriate, disproportionately high and adverse human health or environmental effects of its programs, policies, and activities on minority populations and low-income populations.”[37] In the cover memorandum for that order, President Clinton directly invokes NEPA as a means to that end:

Each Federal agency shall analyze the environmental effects, including human health, economic and social effects, of Federal actions, including effects on minority communities and low-income communities, when such analysis is required by the National Environmental Policy Act of 1969… Each Federal agency shall provide opportunities for community input in the NEPA process, including identifying potential effects and mitigation measures in consultation with affected communities…[38]

Taken together, these documents establish a useful framework for the federal government to put a greater emphasis on environmental justice in future projects. Fifty years on, federal agencies are well-acquainted with the requirements of NEPA and the process of crafting environmental impact statements, making them a convenient vehicle for spreading the principles of environmental justice to federal projects across the country. Major interstate highways, themselves products of federal initiatives, fall squarely within the scope of this initiative to pay more attention to community impacts.[39] It is impossible to know whether this collaborative mindset would lead to the creation of more RVBs across the country, but in a way that is precisely the point: acknowledging the people whose quality of life is at stake, and allowing them a role in deciding which mitigation measures would serve them best.


For the millions of Americans who live near major roadways, the formation of an environmental justice council at the White House is of little comfort. Their health will remain at risk until action is taken, and justice should not mean continuing to suffer while politicians wring their hands in Washington. NEPA set the stage for environmental justice to be a major consideration in our roadway construction projects, and in the decades since its value in this fight has become increasingly clear. Where mitigation measures are being considered, roadside vegetation buffers stand as a proven strategy which can alleviate some of the worst health effects of living close to major roadways. They clean toxic chemicals and particulate matter out of the air, dampen the noise that heavy traffic produces, and can be customized to fit the needs of a given space. They are relatively low-cost and can be implemented more quickly than the alternatives, allowing communities that have long borne more than their fair share of environmental harm to finally breathe a little easier. As the saying goes: The best time to start planting these trees was thirty years ago; the second-best time is today.

Amanda Halter is managing partner of the Houston office of the international law firm of Pillsbury Winthrop Shaw Pittman, a member of the firm’s Environmental & Natural Resources practice section and co-leader of the firm’s Crisis Management team. Amanda helps companies resolve environmental liabilities and negotiate compliance conditions, as well as manage financial and reputational losses associated with a crisis. Her experience includes a diverse array of environmental regulatory, litigation and crisis matters, including contamination investigations and remedial actions, natural resource damages assessments and claims, environment, health and safety compliance counseling, mass toxic tort actions, permitting and planning for large-scale industrial projects, and project impacts mitigation and restoration strategies. Amanda is a native of Houston, a graduate of Rice University and The University of Texas School of Law.

Alex Brenner is a member of the Class of 2023 at The University of Texas School of Law. Alex joined TELJ in Fall 2021 and currently serves as a Senior Editor. He grew up in Connecticut and completed his undergraduate degree at Brandeis University, where he majored in Neuroscience, Biology, and Psychology. After graduation he will be moving to Seattle, WA, to practice environmental law and get lost in the Cascades.


[1]      Exec. Order No. 14008, 86 Fed. Reg. 7,619, 7,630 (Jan. 27, 2021); see White House Environmental Justice Advisory Council, The White House, white-house-environmental-justice-advisory-council (last visited Dec. 22, 2022).

[2]      Fact Sheet: A Year Advancing Environmental Justice, The White House (Jan. 26, 2022), https://

[3]      State and Federal Environmental Justice Efforts, Nat’l Conf. of State Legislatures (Jan. 13, 2022),; Learn About Environmental Justice, Env’t Prot. Agency, (last updated Sept. 6, 2022) (“Environmental justice (EJ) is the fair treatment and meaningful involvement of all people regardless of race, color, national origin, or income with respect to the development, implementation and enforcement of environmental laws, regulations and policies.”).

[4]      EPA Research: Environmental Justice and Air Pollution, Env’t Prot. Agency, https://www.epa. gov/ej-research/epa-research-environmental-justice-and-air-pollution (last updated Nov. 29, 2022).

[5]      Texas Has Refused to Fix Problems in its Air Permitting Program That Affect Environmental Justice and Public Participation, Tex. RioGrande Legal Aid (June 28, 2022),; see also Christopher Dunagan, Why Is So Much Pollution Found in Disadvantaged Communities?, Salish Sea Currents Mag. (Apr. 12, 2021), https://www.

[6]      Katherine Coombs, Highways and Environmental Justice, Env’t Educ. Ctr. (May 16, 2022),; Wendy Q. Xiao, The Road to Racial Justice: Resolving the Disproportionate Health Burden Placed on Communities of Color by Highway Pollution, 52 Colum. Hum. Rts. L. Rev. 911, 955 (2021), files/2021/02/911_Xiao.pdf.

[7]      How Mobile Source Pollution Affects Your Health, Env’t Prot. Agency, mobile-source-pollution/how-mobile-source-pollution-affects-your-health (last updated Dec. 16, 2022).

[8]      Id.

[9]      Fast Facts on Transportation Greenhouse Gas Emissions, Env’t Prot. Agency, (last updated July 14, 2022); see also Light Duty Vehicle Emissions, Env’t Prot. Agency, greenvehicles/light-duty-vehicle-emissions (last updated June 29, 2022) (explaining that “light-duty vehicles” include cars, SUVs, and light duty trucks).

[10]     Health Effects Inst. Panel on the Health Effects of Traffic-Related Air Pollution, Traffic-Related Air Pollution: A Critical Review of the Literature on Emissions, Exposure, and Health Effects 5 (2010), Review_Exec_Summary.pdf.

[11]     Id. at 3.

[12]     Id. at 10.

[13]     Miranda R. Jones et al., Race/Ethnicity, Residential Segregation, and Exposure to Ambient Air Pollution: The Multi-Ethnic Study of Atherosclerosis (MESA), 104 Am. J. Pub. Health 2130, 2132–33 (2014).

[14]     Xiao, supra note 6; EPA Research: Environmental Justice and Air Pollution, supra note 4.

[15]     Mette Sørensen et al., Road Traffic Noise and Incident Myocardial Infarction: A Prospective Cohort Study, 7 PLoS One, issue 6, 2012, at 3.

[16]     Leena Muralidharan et al., Noise Pollution of Local Train and Its Impact on Students Residing Nearby Railway Station, 5 J. of Emerging Techs. & Innovative Rsch. 592, 593 (2018); Haneen Khreis et al., The Health Impacts of Traffic-Related Exposures in Urban Areas: Understanding Real Effects, Underlying Driving Forces and Co-Producing Future Directions, 3 J. of Transp. & Health 249, 249 (2016); Charlotta Eriksson et al., Burden of Disease From Road Traffic and Railway Noise – A Quantification of Healthy Life Years Lost in Sweden, 43 Scandinavian J. of Work, Env’t & Health 519, 519 (2017).

[17]     See, e.g., Andy Hirschfeld, Can Burying Urban Highways Undo Decades of Racial Inequity?, The Daily Beast (May 18, 2022),

[18]     See Eric Moskowitz, True Cost of Big Dig Exceeds $24 Billion With Interest, Officials Determine, (July 10, 2012), 10/true-cost-of-big-dig-exceeds-24-billion-with-interest-officials-determine/.

[19]     See Chris Ingalls, Unexpected Costs Added Nearly $58 Million to SR 99 Tunnel Project Price, KING5 News (Jan. 31, 2019),

[20]     Rich Baldauf, Env’t Prot. Agency, Recommendations for Constructing Roadside Vegetation Barriers to Improve Near-Road Air Quality 6 (2016), si_public_file_download.cfm?p_download_id=528612&Lab=NRMRL.

[21]     Id. at 12.

[22]     Id. at 3.

[23]     See id.

[24]     Id. at 1.

[25]     See id.

[26]     Baldaufsupra note 20, at 3.

[27]     Researchers Assess Roadside Vegetation Barriers with a Suite of Air Monitors, Env’t Prot. Agency, (last updated Apr. 19, 2022).

[28]     See, e.g., Fed. Highway Admin., U.S. Dept. of Transp., Keeping the Noise Down: Highway Traffic Noise Barriers (2001), _construction/keepdown.pdf.

[29]     Traffic Noise & Transportation, Ctr. for Env’t Excellence, https://environment.transportation. org/education/environmental-topics/traffic-noise/traffic-noise-overview/ (last visited Dec. 22, 2022).

[30]     See Baldauf, supra note 20, at 1.

[31]     Id.

[32]     See Susan Barton & Rebecca Pineo, Human Benefits of Green Spaces, Univ. of Delaware, (last updated Jan. 31, 2009).

[33]     Id.

[34]     Mark Hall et al., At the Crossroads: Does the Configuration of Roadside Vegetation Affect Woodland Bird Communities in Rural Landscapes?, 11 PLoS One, issue 5, 2016, at 1.

[35]     Erosion, Sediment and Runoff Control for Roads and Highways, Env’t Prot. Agency (Dec. 1995),

[36]     What is the National Environmental Policy Act?, Env’t Prot. Agency, nepa/what-national-environmental-policy-act (last updated Oct. 26, 2022).

[37]     Exec. Order No. 12898, 59 Fed. Reg. 7,629 (Feb. 11, 1994).

[38]     William Clinton, Memorandum for the Heads of All Departments and Agencies on Executive Order on Federal Actions to Address Environmental Justice in Minority Populations and Low-Income Populations (Feb. 11, 1994), memo_12898.pdf.

[39]     Farrell Evans, How Interstate Highways Gutted Communities—And Reinforced Segregation, (Oct. 20, 2021),