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The New York City Community Air Survey:
Neighborhood Air Quality 2008-2018
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Summary
In 2007, the New York City Department of Health and Mental Hygiene established the New York City Community Air Survey (NYCCAS), the largest ongoing urban air monitoring program of any U.S. City. NYCCAS, which began collecting data in December 2008, is a collaboration between the Health Department and Queens College of the City University of New York and provides data to:
- Help inform the City’s sustainability plan, OneNYC
- Track changes in air quality over time
- Estimate exposures for health research
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This report:
- Provides a summary of key findings, the air monitoring program, monitoring site selection, and descriptions of the pollutants measured
- Describes the trends in air pollutant levels from a decade's worth of data between winter 2008-2009 through fall 2018 for fine particulate matter (PM2.5), nitrogen dioxide (NO2), nitric oxide (NO), black carbon (BC), wintertime sulfur dioxide (SO2) and summertime ozone (O3)
- Presents maps of neighborhood air pollution levels by year
- Identifies the local sources that contribute to high levels of these pollutants in NYC neighborhoods
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Key Findings
Citywide, annual average levels of four key pollutants have gone down between the first year of monitoring, 2009, and the most recent year of data, 2018
| Fine particles (PM2.5) | -32% |
| Nitrogen Dioxide (NO2) | -29% |
| Nitric Oxide (NO) | -47% |
| Black Carbon (BC) | -33% |
Air quality improved significantly after the city required building owners to convert to cleaner heating oils by 2015
Since the first winter of monitoring, average levels of sulfur dioxide (SO2) have declined by 95%. In 2018, only 17 of our 60 core sites detected any SO2, and the levels at those sites were similar to SO2 levels measured on Whiteface Mountain in the Adirondack Mountains, demonstrating the success of the clean heating oil requirements.Air quality changes with location
PM2.5, NO2, NO, and BC are highest in:
- Areas of higher traffic density
- Areas with higher density of buildings with heat and hot water boilers
- Industrial areas
- The outer boroughs
- Areas that are downwind of high NOx emissions
- Areas with fewer combustion emissions
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Pollutants Measured by NYCCAS: Health Effects and Sources
Fine Particles
Fine particles (PM2.5) are tiny airborne solid and liquid particles less than 2.5 microns in diameter. PM2.5 is the most harmful urban air pollutant. It is small enough to penetrate deep into the lungs and enter the bloodstream, which can worsen lung and heart disease and lead to hospital admissions and premature deaths. PM2.5 causes cancer.
PM2.5 can either be directly emitted or formed in the atmosphere from other pollutants. Fuel combustion in vehicles, boilers in buildings, power plants, construction equipment, marine vessels and commercial cooking are all common sources of PM2.5. Between 30% to 40% of the PM2.5 in New York City's air comes from sources in areas upwind from the city, such as coal-burning power plants in the Midwest.
Black Carbon
Black carbon (BC) is the sooty black material emitted from gas and diesel engines, coal-fired power plants, and other sources that burn fossil fuels. It comprises up to 20% of fine particulate matter in New York City. Unlike other fine particles, BC is primarily from local sources. Inhalation of BC is associated with health problems, including respiratory and cardiovascular disease, cancer and birth defects. BC also contributes to climate change by altering the patterns of rain and clouds.
Nitrogen Dioxide and Nitric Oxide
Nitrogen dioxide (NO2) and nitric oxide (NO) are part of a group of pollutants called “oxides of nitrogen” (NOX). Exposures to NOX are linked to increased emergency department visits and hospitalizations for respiratory conditions, particularly asthma. NOX also reacts with other compounds in the atmosphere to form PM2.5 and O3. A variety of combustion sources produce NOx in New York City, including motor vehicles, buildings, marine vessels and construction equipment.
Ozone
Ozone (O3) forms at ground level when NOX emissions combine with sunlight and other airborne pollutants. Measured O3 concentrations are often highest in the summer and downwind from areas with high NOx emissions, such as places with high traffic density. In areas with heavy traffic, NOX reacts with any ground-level O3 to reduce O3 concentrations. As a result, the Health Department has observed lower O3 levels near roadways, in city centers and in other areas of high emissions density. Higher levels of O3 are seen in areas away from dense traffic and building emissions.
Sulfur Dioxide
Sulfur dioxide (SO2) is produced mainly by burning oils with high sulfur content, such as No. 4 and No. 6 oil (also known as residual fuel oil), or high-sulfur No. 2 oil. The primary use of fuel oil in NYC is to heat buildings and water, which is why we only monitor it in the winter. Some high-sulfur oil is also used to generate electricity and power marine vessels. SO2 exposures can worsen lung diseases, causing hospitalizations and emergency department visits for asthma and other respiratory conditions. SO2 also contributes to the formation of PM2.5 in the atmosphere, resulting in PM2.5 exposures downwind of SO2 emissions.
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NYCCAS Methods
The Health Department designed NYCCAS to understand how average air pollution levels vary from place to place within New York City. The New York State Department of Environmental Conservation also has a network of nineteen air quality monitors in New York City that are required by the Federal government, but they are mounted on building roofs. We placed our air samplers at street level to measure pollution where people spend time, and where traffic-related pollution levels are usually higher.
NYCCAS staff mount samplers on street light poles 10 to 12 feet off the ground along residential and commercial streets and in parks. The monitors use a small battery-powered pump and filters to collect air samples. Our air samplers are deployed at each NYCCAS site once each season and collect data for a two-week period. Samples are collected in all seasons for NO, NO2, PM2.5 and BC; in the summer for O3; and in the winter for SO2. For more details on sample collection methods, see Appendix 1 (PDF).
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NYCCAS Sites
The monitoring locations represent a wide variety of New York City environments – sidewalks, busy streets, parks and quiet neighborhood roads. Most of the sites (80%) were chosen by the Health Department at random to ensure representation in all types of neighborhoods, including residential, commercial and industrial areas. The remaining sites were selected because they are near potentially high-emission locations that were not captured in the random assignment. These include Times Square, the Port Authority Bus Terminal and the entrance to the Holland Tunnel. The locations vary in tree canopy and in the density of traffic and buildings. The number of sites has changed over the years as we have learned about air quality in our city. In 2018, we monitored 78 routine locations and an additional 15 sites in low-income neighborhoods that would benefit from additional monitoring to understand potential sources of emissions. We refer to these as Environmental Justice Sites on the map.
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Pollutant Maps
Since it is impossible to sample the air in every location in New York City, we monitor representative sites to determine how pollution levels vary in relation to traffic, buildings, trees and other neighborhood factors. We use NYCCAS monitoring data along with data on land use, traffic, building emissions and other neighborhood factors around the monitors to build a land-use regression (LUR) model. We then used the associations from these models to estimate the seasonal average air pollution levels at locations across the city, including places where no NYCCAS measurements were collected. For more details on emission source data, see Appendix 1 (PDF). For more details on the analysis methods, see NYCCAS Scientific Publications.
In the maps below, you can select a pollutant to see how air pollution is distributed throughout the city and how it has changed over time. Winter and summer average maps for BC, NO2, NO and PM2.5 are available in Appendix 2 (PDF).
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Pollutant Sources
Since monitoring began in winter 2008-2009 in New York City, we have seen a decrease in most of the air pollutants we measure. However, the concentration of each of these pollutants continues to be higher in industrial areas, as well as areas of higher traffic and building density. Air pollution changes not only by neighborhood, but also by season. Some pollutants are highest in certain seasons of the year because of either weather patterns or emissions sources. For example, SO2 mainly comes from big buildings burning No. 6 (the dirtiest) fuel oil for heat and hot water. We only monitor SO2 in the winter when heating demand is highest. SO2 levels have gone down dramatically since Local Law 43 of 2010 prohibited the burning of heavy fuel oil (No. 6) in New York City buildings.
The figure below illustrates how the levels of each air pollutant change by season from winter 2008-2009 to fall 2018. We break out locations with high, medium and low densities of the most common sources of each. In winter 2017-18 there were too few sites with SO2 values above the detection limit for us to include it in this chart.
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Pollutant Predictors
NYCCAS data were analyzed using a land-use regression (LUR) model. LUR models estimate associations among pollution levels, average traffic, building emissions, land use and other neighborhood factors around the monitoring sites. The pollution sources that contribute most to differences in concentrations of NO, NO2, BC, and PM2.5 across NYC are listed in the table below. SO2 is now so low in NYC that it is not possible to build a LUR model for the most recent years of data.
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Conclusion
This report underscores the importance of emissions reduction efforts over the past decade and highlights the continued need to reduce emissions citywide. The City’s sustainability plan, OneNYC, and its roadmap to reduce greenhouse gas emissions, 80x50, have already and will continue to improve air quality and provide important public health benefits to all New Yorkers. These strategies and measures include:
- Transitioning to more efficient, less polluting light-duty and heavy-duty vehicles
- Reducing motor vehicle use by shifting to more sustainable modes of transportation
- Creating more efficient freight networks and expanding truck retrofit and replacement programs
- Reducing fossil fuel combustion in buildings.
Additionally, reducing emissions from other widely distributed sources of pollution, such as BC and PM2.5 from commercial charbroiling, will contribute to improved air quality in the future.
More Information:
- New York Community Air Survey: current and past reports
- Appendix 1 (PDF) : Sampling Methodology and Data Sources for Emissions Indicators.
- Appendix 2 (PDF) : Seasonal Average Pollutant Maps.
- Appendix 3 (PDF) : Community District Average Pollution Levels
- Environment & Health Data Portal : Neighborhood-level data and neighborhood air quality reports
- The Public Health Impacts of PM2.5 from Traffic Air Pollution data story.
- NYCCAS Air Pollution Rasters on NYC OpenData.