Air pollution has drastic impacts on individual’s life quality and life expectancy. It is associated with heart attacks, asthma attacks, premature mortality, and numerous other long-term health consequences. Some pollutants have a more serious impact on human health than others. Particulate matter 2.5, or PM2.5, is one of the most harmful pollutants. These are tiny particles that can go deep into the lungs and bloodstream. It enters the atmosphere by being either directly emitted from sources, such as factories, or formed in the atmosphere by chemical reactions. The main gases that are part of this secondary process are sulfur dioxide and nitrogen oxides. While the presence of these pollutants leads to dangerous living conditions locally, they also have implications for environmental conditions globally.

A Visualization of Air Pollution Emissions in the United States

Air pollution peaked in 1970 and has been generally decreasing since then in the United States. This is in part due to the Clean Air Act, which passed in 1970. This created new emission standards with greener impacts, such as requiring factories to emit less pollution. While this has been a great shift in our country’s environmental quality, there are lasting effects of the rise in pollution. Pollution in the atmosphere contributes to the greenhouse gas effect. This means that pollution in the atmosphere works to trap heat near Earth’s surface. Even if all pollution emissions stopped right now, they would not go away quickly. Some gases, like carbon dioxide, have atmospheric residence times of hundreds of years. However, regardless of a pollutant’s atmospheric residence time, its presence in the atmosphere could cause damaging chemical reactions, such as nitrogen oxide and non-methane volatile organic compounds (NMVOCs).

Additionally, not all countries are decreasing their emissions. The environmental actions of a country can affect the entire world.

In the 1900s, the amount of NMVOC and nitrogen oxide emissions shot up across the continents. Most continents decreased their emissions, but Asia’s emissions continue to rise. This is in part due to the large populations held in that region, which means more energy consumption and production.

The Earth is facing widespread warming due to the increased atmospheric presence of global emissions, which leads to the greenhouse gas effect. Everybody on Earth is impacted by these changes in our climate, whether directly or indirectly. However, some groups of people have a disproportionate share of the burden of consequences. This leads to vulnerable groups experiencing higher rates of illness. These warming patterns create unsafe conditions for people, putting them at risk of heat-related illnesses—which can be deadly.

Ozone is formed in the troposphere by the chemical reaction of nitrogen oxide, volatile organic compounds (VOCs), and solar radiation. Due to the increase in both nitrogen oxide and VOCs in the environment, ozone is increasingly common close to the surface. Smog develops from the formation of ozone at ground level. The ingredients needed in this process make it a feedback loop. Heat is needed, in the form of solar radiation, leading to high levels of ozone being more likely to form in warmer temperatures. Global warming, in part due to increased ground-level ozone, makes it easier for ozone to form. This continues the cycle.

Ozone is harmful to life on Earth when it is close to the surface. In the stratosphere, about 12 miles above the surface, it is helpful in protecting the surface from the sun’s radiation. However, at ground level, it is extremely detrimental, both to the Earth’s ability to regulate its temperature and to the health of people and other life. The surplus of ozone created from greenhouse gases has led to a decrease in air quality in many regions of the world.

People of color are disproportionately impacted by the presence of ozone. Many census tracts with the highest proportions of people of color have higher amounts of ozone. The area of high point density on the right side of the graph is very concerning.

Ozone can lead to immediate breathing problems for people living in an area with high amounts of ozone. This can manifest as shortness of breath or respiratory infections. Along with short-term impacts, there are many long-term risks. This includes increased metabolic disorders, nervous system issues, reproductive issues, and even cardiovascular mortality.

The uneven distribution of ozone across census tracts in Brooklyn coupled with its severe health risks indicate an urgency for equitable and resilient environmental solutions, particularly as the climate continues to change.

The average daily temperature in Brooklyn has increased over time between the two time periods of 1954-1986 and 1987-2022. While it seems to be a small difference, a temperature change of even one degree Fahrenheit has drastic impacts on Earth’s climate.

Even locally, heat waves would be more extreme, rainstorms would be more intense, and sea levels would rise. This puts vulnerable people in particular in a lot of danger.

People living in cities are greatly impacted by increases in temperature due to the urban heat island effect. Places with a lot of structures and infrastructure absorb and re-emit the sun’s heat much more than natural landscapes. Urban areas that lack greenery and have an abundance of these structures can be about 7 degrees Fahrenheit warmer than outlying areas. In some instances, it can get even hotter.

In urban heat islands, there is an influx in air conditioning usage, which can exacerbate negative air quality conditions with the increase in energy demand. This is just one example of another feedback loop that leads to poor environmental quality.

Different groups of people have varying levels of vulnerability to heat-related illnesses. Low-income populations are at a greater risk. They are more likely to lack air conditioning and live in poor housing conditions. It can be more difficult for them to find cooler shelters during extreme heat. Other heat-sensitive populations include older adults, young children, people who work outdoors, and people in poor health.

A strategy to combat the heat island effect and protect vulnerable populations is increasing tree density. Trees and vegetation shade surfaces and deflect solar radiation from the sun. This can have a dramatic effect on the surface temperature of an area, while also aiding in carbon sequestration. This is a great strategy to keep cities resilient to widespread temperature increases and the increasing frequency of heat waves.

A Map of Trees and Temperature in Washington D.C.

This web app depicts tree cover and the temperature difference from the urban area mean temperature, by census blocks in D.C. The temperature differences variable represents how much each block group fell above and below the urban area temperature mean. Positive values (red) indicate block groups that are hotter than average. Negative values (white) indicate block groups that are cooler than average. The tree canopy variable represents the percentage of each block group’s area that is tree canopy.

The relationship between tree cover and temperature is stark. The areas with few trees have high comparative temperatures. The block groups that have a higher amount of tree canopy tend to be cooler in temperature than the urban area mean. This is a perfect example of the urban heat island effect, and it emphasizes how important trees are to a city’s ability to regulate its temperature.

Think about how different it feels to walk down a street with no trees compared to a road with a lot of shade from trees. Now, imagine living in an area that has few trees for consecutive blocks. This is particularly dangerous in cities that have a lot of pedestrians because there are so many people experiencing the extreme urban heat. New York City is an example of a city with many walkers. The city is oriented toward walking and public transportation. This is great for the environment, but healthy environmental conditions for pedestrians are critical to ensure safety.

The proportion of people walking to work in Brooklyn is much larger than in across the United States. In fact, it is about four times as large. The other major difference in this breakdown is that most people take public transportation to work in Brooklyn, while that is the fourth common method across the United States. The vast majority of people drive to work. This comparison provides a standard to compare Brooklyn to.

While many people take public transportation to work in Brooklyn, a lot of those routes require people to walk somewhere first. For example, having to walk to a bus stop or subway station. This leads to people having to be outside in the sun significantly more than the rest of the United States. A lot of people drive to work in the United States, whether that is alone or carpooling. This can serve as an individual shelter from heat, compared to traveling on foot to work.

The urban heat island effect can make it dangerous to walk in cities with a lack of trees. The large number of New Yorkers that rely on traveling on foot to get around the city makes it particularly important to ensure adequate environmental conditions.

Tree distribution is New York city is not even. Some areas have an abundance of trees while others suffer from low tree density. The eastern part of Brooklyn has lower tree density while the center has higher tree density. Brooklyn is a very urbanized borough and is extremely susceptible to the heat island effect. Based on the relationship between trees and surface temperature that was explored in the map of DC, it is reasonable to expect that the eastern part of Brooklyn with low tree density will be warmer than areas in the center with higher tree density.

As a result, people in the areas in the east may be more vulnerable to heat-related illnesses.

Different areas of Brooklyn have vastly different demographic characteristics—it is a very diverse place. It is important to examine if particular groups of people tend to have decreased environmental quality compared to others. If these populations are identified, programs can be implemented to improve their environmental conditions, such as planting more trees to help mitigate heat stress on health.

This data is normalized by the population. The average count of trees per person is highest in census tracts that have a majority of white people. Census tracts with a majority of Asian people have the lowest number of trees per person, on average.

This indicates that white people have a disproportionately larger share of the trees in Brooklyn, NY, while census tracts with a majority population of people of color lack trees. These bars should be similar across races.

These results have some concerning implications. Census tracts with a majority of white people typically have more tree cover, and thus, more shade and cooler temperatures in warm seasons. People of color do not have as many trees available in their neighborhoods to keep themselves cool. This increases vulnerability to heat-related illnesses, putting the people in these areas in danger.

Given that higher temperatures can lead to a multitude of health consequences, census tracts that have a majority of people of color are most at risk of serious illnesses from heat. These areas may not be as resilient to the changing climate.

While the disparities of environmental quality for racial groups is a large part of the investigations of environmental justice, there are additional demographic characteristics that are important to examine.

New York City is a big renting city. Many more housing units are being rented than are owned. This sets the number of trees per acre into context and suggests the proportion of the population in Brooklyn that rents versus owns their housing unit. There is a higher number of trees per acre for census tracts that have a majority of owned units, on average.

The mismatch in the distribution of trees between areas of high and low ownership is indicative that a large portion of the many people renting in Brooklyn may not have adequate tree cover. It is also suggestive of a relationship between income and tree distribution. Owning property can be difficult to do because it is very expensive—particularly in New York City.

This visualization indicates that there may be a relationship between the average number of trees, average median income, and most common educational attainment in each census tract.

Based on these points, there seems to be a positive relationship between the number of trees and median income. Additionally, the number of trees generally increases the higher the most common education attainment level is. The census tracts with the majority of people having a high school degree or less have the lowest amount of trees in their neighborhoods.

The areas with low tree density are places that will likely become much warmer than the rest of Brooklyn on hot days. This also means that the people in these areas will be at a higher risk of illness. Inadequate tree density is a challenge that can be improved with proper planning and work. Increasing tree density in areas with vulnerable populations is a solution that would not only benefit residents, but also the Earth.

These distributions are some of the many examples of the disproportionate environmental burdens that marginalized communities face, particularly as the Earth experiences climate change. The first step is identifying locations of need through spatial, quantitative, and qualitative analysis. Many forms of environmental injustice can be remedied through resilience-focused work. Preparing communities for climate change through infrastructure projects or other sustainable design strategies can make them resilient against future environmental harm. Examples of other important resiliency projects are those that are focused on mitigating the impact of sea level rise. In New York City, the East Side Coastal Resiliency Project and the Lower Manhattan Coastal Resiliency Project are working on this.

Unfortunately, our climate continues to change and become more extreme. Well-planned resiliency projects can minimize the impacts of this while also promoting environmental equity within communities.

References: