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Center for Advancing Research in Transportation Emissions, Energy, and Health (CARTEEH)

A USDOT University Transportation Center

Reductions in Air Pollution

There is growing evidence that green space can contribute to reductions in urban air pollution since vegetation can act as natural filters for certain air pollutants.1,2 Therefore, the level of air pollution in cities can be an indicator to demonstrate the effectiveness of strategies that aim to improve and expand residents’ access to green space, such as parks, green roofs and walls, and tree-lined streets. In addition, green space can provide numerous other societal benefits, such as enhanced biodiversity and recreational opportunities.3

This indicator helps determine the effectiveness of the following objectives

  • Less Contamination
  • Less Emissions
  • Less Traffic Noise
  • Connectivity and Inclusion
  • Healthy Destinations
  • Less Traffic Violence
  • Active Transportation
  • Green Space

Data Collection

The Air Quality Index (AQI) website provides a lot of background information on air pollution; it is also a great resource for collating data on the level of air pollutants. The AQI is designed to help one understand what levels of air pollution are considered unhealthy and then take steps to protect their own health. For example, air quality is considered satisfactory if the AQI value is below 100. However, if the AQI value is above 200, air quality is considered unhealthy for sensitive groups, such as people with respiratory problems or heart conditions. Moreover, if the AQI value exceeds 300, air quality is considered unhealthy for everyone.

Data on the AQI value for a particular area is on the official website. However, the AQI values are updated hourly, so it is pertinent to check them often to stay updated on the air quality in a particular area.4

Examples

Environmental Protection Agency (EPA) and NAAQS

The Environmental Protection Agency (EPA) estimates that reductions in air pollution can have several benefits for public health and the environment. The EPA uses the Clean Air Act to limit emissions from factories, power plants, and automobile industries. The EPA also works with state and local governments to develop plans to reduce air pollution.

The Clean Air Act has successfully reduced air pollution and improved air quality. The EPA uses the National Ambient Air Quality Standards (NAAQS) to measure the effects of the Clean Air Act. The NAAQS sets standards for six common air pollutants: carbon monoxide, lead, nitrogen dioxide, ozone, particulate matter, and sulfur dioxide. If the levels of these pollutants in the air exceed the recognized standards, then the area is considered to be “polluted.” The EPA monitors air pollution levels across the country and works with state and local governments to reduce pollution levels. The EPA’s monitoring program has been key to measuring these trends and ensuring that the United States continues to progress in reducing air pollution.

https://www.epa.gov/clean-air-act-overview

1. Midouhas, E., Kokosi, T., & Flouri, E. (2019). Neighbourhood-level air pollution and greenspace and inflammation in adults. Health & Place, 58. https://doi.org/10.1016/j.healthplace.2019.102167
2. University of Washington, College of the Environment. (2018). Green Cities: Good Health. https://depts.washington.edu/hhwb/Thm_Risk.html
3. Kruize et al. (2019). Urban Green Space: Creating a Triple Win for Environmental Sustainability, Health, and Health Equity Through Behavior Change. Int J Environ Res Public Health, 16(22). https://doi.org/10.3390/ijerph16224403
4. Air Quality Index (AQI). In: Encyclopedia of Quality of Life and Well-Being Research. Dordrecht: Springer Netherlands; 2014. p. 120–120.