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Urban Silviculture

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Air Quality in New York City

Air quality in New York City is a complex topic that this webpage aims to make more accessible by providing basic information and resources.

What is Particulate Matter and what does it have to do with air pollution?

Particulate matter is one of six types of air pollution regulated by the U.S. Environmental Protection Agency. Particulate matter is categorized by size, and is especially important because of its role in asthma and other health issues. Particulate Matter 2.5 (PM 2.5) includes all particulate matter that is 2.5 microns in diameter and smaller. PM 2.5 is of concern because the particles are small enough to pass deep into the lungs, and even into the blood stream. To learn more about this category of air pollution, see the following links:

Three questions you might want to consider:

The EPA collects local air quality data to determine if locations are in compliance with the agency's regulations. Air quality reports depend on how data is collected and analyzed. So when you read or hear about air quality reports, you may want to ask:

  • How often is the air measured and are the results averaged?

Federal regulations for PM 2.5 are based on daily and annual limits (see below). At every monitoring site, data is averaged over 24 hours and over one year to determine that location's air quality. Averaging over that much time can have a significant impact on results. Imagine a passing vehicle that emits excessive pollution. It may produce emissions that would exceed the EPA limit, but not if averaged with samples of relatively clean air from before and after the vehicle passed. This Urban Silviculture project measures particulate matter levels every six seconds, which is about the frequency of human respiration.

  • What is measured?

The EPA measures the mass of the PM 2.5 in a sample of air. The Urban Silviculture project measures the mass of an air sample, but also the number of particles in it. Smaller particles have a potentialy greater health impact, but they also have less mass, so their prevelance may be masked if they are described by mass instead of number.

  • Where is it measured?

The EPA monitors are located on the rooftops of buildings. Particulate matter disperses and becomes less concentrated as it moves away from its source, so the air we breathe might be worse than rooftop monitors indicate. The Urban Silviculture project measures the pollution at the street level, which is closer to both the source of the pollution and to where people breathe.

You can read the details about how the EPA measures PM 2.5: Click here for general information about PM2.5 Data Analysis. Click here for comparing measured particulate matter data to EPA's recently revised National Ambient Air Quality Standards for Particulate Matter (40 CFR Part 50).

Children are especially susceptible to air pollution. Children are most affected by PM 2.5 because:

  • They spend more time outdoors, are more active, and have a higher breathing rate than adults
  • Their lungs are more permeable than adult lungs, so particulate matter can pass through them more easily
  • Their bodies are still developing and early lung damage has lifelong repercussions
  • In addition, they are at risk when they are still in the womb, leading to decreased birth weight, and increased risk of preterm birth and infant mortality

School buses are an important source of air pollution, not only because of the pollution they emit, but also because of childhood exposure. Read here about the agreement with transportation companies to reduce pollution by idling school buses with former NY State Attorney General Spitzer.

You can read more about asthma and what organizations are doing at the following links:

What you should know and what you can do about it:

The federal limit on PM 2.5 was recently reduced to 35 micrograms per cubic meter averaged daily, from 65 micrograms per cubic meter averaged daily. You can read more in the EPA announcement.

PM 2.5 is produced from many sources, including cars and trucks. Idling engines produce unnecessary pollution, so the city allows idling for a maximum of only 3 minutes. You can kindly ask drivers to turn off their engine after that, and report violations by calling 311. You can learn more by reading about idling on the website of NY State Attorney General Andrew Cuomo.

Read about transportation improvements to our air:

For comments, questions, or suggestions, please contact us.