Air Pollution On Busy Streets: A Health Hazard?

Living on a busy street can expose you to high levels of air pollution, which can have significant impacts on your health. Research has shown that air pollution from busy roads increases the risk of cardiovascular, respiratory, and reproductive health issues, as well as lung cancer and premature death. The type of vehicles, traffic density, and proximity to the road are all factors that contribute to the level of pollution you may be exposed to. Certain groups, such as children, older adults, and people with pre-existing cardiopulmonary conditions, are more vulnerable to the health risks associated with air pollution. While some strategies, like roadway design and noise barriers, can help reduce pollution exposure, living on a busy street still poses health risks.

Health risks: cancer, asthma, heart disease, and more

Air pollution is a major threat to global health, causing more than 6.5 million deaths each year. It is a mix of hazardous substances from human-made and natural sources. Vehicle emissions, fuel oils, natural gas, manufacturing by-products, and power generation are some of the primary sources of air pollution. People living near busy roads are most affected by traffic-related air pollution.

Living on a busy street can expose you to various air pollutants, leading to several short- and long-term health risks. Short-term exposure to air pollution can cause respiratory infections, reduced lung function, and aggravated asthma. It can also trigger asthma attacks, especially in children, and lead to acute bronchitis. Additionally, it may increase the risk of heart attacks and abnormal heartbeats.

Long-term exposure to air pollution is even more concerning. It increases the risk of developing chronic diseases, including lung cancer, heart disease, and chronic obstructive pulmonary disease (COPD). Fine particulate matter in the air can impair blood vessel function and accelerate the calcification of arteries, contributing to cardiovascular disease. Prolonged exposure to air pollution is also associated with an increased risk of stroke, ischaemic heart disease, pneumonia, and lung cancer.

Air pollution is particularly harmful to vulnerable groups, including children, older adults, pregnant women, and people with pre-existing health conditions such as asthma, COPD, diabetes, and heart disease. Children living near busy roads have a higher chance of developing asthma, and air pollution can worsen asthma symptoms and trigger attacks. It can also cause lung damage and increase the risk of respiratory infections. For pregnant women, exposure to air pollution is associated with an increased risk of premature birth, low birth weight, and adverse pregnancy outcomes.

Additionally, air pollution has been linked to oxidative stress and inflammation in human cells, which can lay the foundation for chronic diseases and cancer. The specific pollutants of greatest concern for public health include particulate matter (PM), carbon monoxide (CO), ozone (O3), nitrogen dioxide (NO2), and sulphur dioxide (SO2).

Distance matters: how far is too far?

Living on a busy street can expose you to high levels of air pollution, which can have significant impacts on your health. The distance you live from a busy road can play a crucial role in reducing these harmful effects.

Research has shown that air pollution levels and their associated health risks vary depending on how close you live to major roads and freeways. In the US, over 45 million people live within 300 feet of a busy road, and nearly 20% reside near high-volume roads. California air quality regulators have identified a 500-foot zone around freeways where it is considered unhealthful to locate homes, schools, and daycare centres, due to elevated pollution levels and increased rates of asthma, cancer, heart disease, and other illnesses.

Studies have found that pollutant concentrations generally decrease with distance from the source. For example, in Amsterdam, higher levels of NO2, nitric oxide, carbon monoxide, and black smoke were detected at sites influenced by traffic compared to background sites. Similarly, in a study in Montreal, NO2 concentrations were found to decrease with distance from a busy highway, with the greatest reduction occurring within the first 200 metres.

The type of road and surrounding environment also play a role. At-grade freeways, where lanes are level with surrounding buildings, are particularly harmful as they place vehicle tailpipes closer to people. In contrast, vertical separation, such as an elevated or depressed freeway, can help disperse pollutants. The presence of sound walls, vegetation, and varying building heights can also reduce pollution levels by blocking emissions and facilitating their dispersion.

To protect yourself, aim to live beyond the high-pollution zones identified by local regulators, typically beyond 500 feet from busy roads or freeways. If this is not possible, consider the following strategies:

• Keep windows closed and use air conditioning or a portable HEPA filter to reduce indoor pollution levels.
• Choose locations with sound walls, thick vegetation, or varying building heights, which can provide some protection from emissions.
• Opt for neighbourhoods with elevated or depressed freeways, rather than at-grade freeways, to increase the distance from vehicle tailpipes.
• Avoid "street canyons" where pollution can become trapped due to the lack of open spaces for dispersion.

Vehicle types: older cars and trucks increase pollution

Living on a busy street can expose you to high levels of air pollution, which can have significant health impacts. While various factors contribute to air pollution on busy streets, older cars and trucks are significant culprits.

Older vehicles, particularly those manufactured before 1980, often lack advanced emission-control equipment, or this equipment may no longer function properly. As a result, they tend to emit pollutants at much higher levels than newer vehicles. For example, on a typical hot summer day in the United States, pre-1980 cars emit approximately 40% of the hydrocarbon, 40% of the carbon monoxide, and 25% of the nitrogen oxide emissions of the entire car fleet, despite accounting for only 8% of total miles driven.

The impact of older vehicles on air pollution is evident in various studies. For instance, neighbourhoods in Los Angeles with higher levels of traffic pollution tend to have more older, higher-polluting cars and diesel trucks on their streets. In contrast, wealthier areas with newer cars exhibit lower pollution levels. Similarly, a study in Amsterdam found higher levels of NO2, nitric oxide, carbon monoxide, and black smoke at sites influenced by traffic, with stronger associations between these pollutants and daily mortality in the subpopulation living along busy roads.

The harmful effects of older vehicles fall disproportionately on specific communities. In California, for instance, neighbourhoods with the highest exposure to fine particulate pollution from older vehicles are predominantly in central Los Angeles and other low-income communities of colour. This disparity arises from historical redlining and discriminatory government policies that relegated people of colour to areas surrounded by busy roads and other sources of high pollution. As a result, Black and Latino residents often rely on older, less fuel-efficient vehicles, which compromises their health and increases their economic burden due to higher fuel and maintenance costs.

To address this issue, states and organisations have explored accelerated vehicle-retirement (AVR) programs. These programs aim to reduce emissions by offering incentives or purchasing older, highly polluting cars (typically pre-1980 models) to scrap them. However, the cost-effectiveness of AVR programs has been debated, and it is essential to consider factors such as the size, duration, and location of the programs.

Pollution solutions: noise barriers, vegetation, HEPA filters

Living on a busy street can expose you to high levels of air pollution, mainly from vehicle emissions. This can have adverse effects on your health. To combat this, several solutions can be implemented to reduce air pollution and its impact, including noise barriers, vegetation, and HEPA filters.

Noise barriers, also known as sound walls, are roadside structures designed to reduce traffic noise and dilute vehicle emissions. These barriers can effectively lower pollutant concentrations for nearby populations, especially those downwind of the road. Studies have shown that noise barriers can reduce pollutant exposures for those living or spending significant time near high-traffic roadways, who are at an increased risk of adverse health effects.

Vegetation and green spaces have also been proven to reduce airborne pollutant concentrations. The presence of plants and trees can mitigate air pollution through deposition, dispersion, and modification. The deposition mechanism, which involves the settling of particulate matter on plant leaves, has been the most studied. Green space interventions can be optimised by considering plant selection, spatial setup, ventilation, and maintenance, along with the supplementary effects of vegetation on temperature and water.

HEPA filters, or High-Efficiency Particulate Air filters, are a type of mechanical air filter. HEPA filters can trap and remove at least 99.97% of dust, pollen, mold, bacteria, and any airborne particles larger than 0.3 microns. This makes them extremely effective at improving indoor air quality and reducing the health risks associated with air pollution.

By implementing these solutions, such as constructing noise barriers, incorporating vegetation and green spaces, and utilising HEPA filters, the air pollution levels and associated health risks for people living on busy streets can be significantly reduced. These measures can complement existing pollution control programs and provide short-term improvements in air quality, ultimately enhancing the well-being of those affected by traffic-related emissions.

Overall, a combination of these strategies, along with emission control technologies and direct pollution reduction programs, offers a comprehensive approach to mitigating the impact of air pollution on individuals residing or working near busy streets.

Building design: how buildings can reduce exposure

Living near a busy street can expose you to air pollution, which has been linked to adverse health effects, including asthma, cardiovascular disease, and lung problems. Building design plays a crucial role in reducing occupants' exposure to air pollution. Here are some ways that buildings can be designed or modified to minimize the impact:

Filtration and Ventilation Systems:

Mechanically ventilated buildings should have well-maintained and improved filtration systems to reduce exposure to air pollution. New buildings can be designed with adequate filtration in ventilation systems, ensuring that occupants breathe cleaner air. High-efficiency air filters can be installed in central heating, air-conditioning, or ventilation systems to effectively capture pollutants. Proper ventilation is essential, as it helps dilute and remove indoor pollutants, preventing them from accumulating and reducing overall exposure.

Distance and Orientation:

When designing new buildings, it is crucial to keep occupants as far away from busy roadways as possible. This can be achieved by strategically positioning buildings at a distance from major roads and highways, preferably beyond 500 feet, where air pollution concentrations tend to be higher. Additionally, vertical separation from freeways or elevated roads can help disperse pollutants more effectively.

Building Orientation and Surroundings:

The orientation and surroundings of a building can influence the dispersion of pollutants. When designing buildings near major roads, consider incorporating varying building heights, open spaces, parks, and natural obstacles like sound walls with thick trees and plants. These features help disperse pollutants up and away from the immediate vicinity of the building, reducing the concentration of pollutants that occupants are exposed to.

Air Cleaning and Weatherizing:

In addition to source control and ventilation, air cleaning is another approach to moderating indoor air pollution. Portable true HEPA filters can be placed in occupied areas to help remove particulate matter and other pollutants. Weatherizing, or sealing and insulating, buildings can also be coupled with proper ventilation to maintain healthy indoor air quality while saving energy.

Region-Specific Considerations:

Air pollution varies across different regions, with specific pollutants being more prevalent in certain areas. A region-specific review can help identify the major indoor and outdoor air pollutants in each location. This knowledge can then inform the design and modification of buildings to address the unique challenges posed by local air pollution.

By implementing these design strategies, buildings can significantly reduce occupants' exposure to air pollution, creating healthier and more sustainable indoor environments.

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