AirCounts is a new online tool–developed by Abt Associates—to help large and medium-sized cities calculate the health benefits of air quality improvements and the economic value of those benefits.
Why Cities Need AirCounts
As cities begin establishing climate change policies and programs to improve air quality, policymakers will need to know the benefits those programs are expected to reap—benefits such as fewer premature deaths and decreased cardiovascular and respiratory problems as well as the financial savings that will result.
Using this map (or the drop-down menu), choose one of the C40 or other cities represented. C40 Cities are a network of the world’s megacities which are committed to addressing climate change. This will transport you to the city’s profile displaying its ambient fine particulate matter concentrations, urban population, per capita income and mortality rate. Then use the online calculator to determine the benefits from various reductions in fine particulate matter emissions that you specify.
While the benefits quantified here are based on only premature mortality, Abt Associates can provide results for additional health endpoints. We can develop customized analyses for virtually any geographic area and incorporate time as an analytical dimension.
Method and Data
For a user-specified annual reduction in ground-level PM2.5 emissions, AirCounts estimates the number of deaths avoided and their economic value.
- Results are driven by city-specific intake fractions that convert changes in emissions to changes in air quality;
- Background PM2.5 levels (approximated using satellite remote sensing data);
- Concentration-response (C-R) function;
- Urban population characteristics (size and mortality rate); and
- Income per capita.
The modeling year is 2010; avoided deaths are expected to occur over a 20-year period and their present value is shown in 2010 US dollars at a 3% discount rate.
AirCounts Viewable City Data
These data can be viewed in each city's profile by choosing a city in the drop-down menu or clicking on a city on the map.
The C40 Cities Climate Leadership Group is a network of large world cities, which are committed to implementing sustainable climate-related actions. The local actions are intended to help address climate change globally.
AirCounts calculates results for all C40 cities (indicated by the "C40Cities" logo on the City Profile), plus several other large cities. The drop-down menu on the Cities page contains the full list of cities currently included in AirCounts. We plan to add several other medium sized cities in the future.
We estimated city-specific ambient PM2.5 concentrations using satellite remote sensing data downloaded from the Atmospheric Composition Analysis Group at Dalhousie University. Data are available online.
While more geographically-resolved, our approach is similar to that used in:
van Donkelaar A., R. V. Martin, M. Brauer, R. Kahn, R. Levy, C. Verduzco, and P. J. Villeneuve. 2010. Global estimates of ambient fine particulate matter concentrations from satellite-based aerosol optical depth: development and application. Environ Health Perspect.;118:847–855.
For the majority of cities, 2010 urban population estimates come from the UN's World Urbanization Prospects: The 2007 Revision Population Database. The 2010 urban population estimate for Essen/Rhur comes from Statistisches Bundesamt Deutschland (2012).
Adult mortality rates are derived from life tables for WHO Member States provided by the World Health Organization's Global Burden of Disease Project, which estimates the burden of premature mortality and morbidity across regions, diseases, and risk factors, including air pollution and GNI per capita.
Gross National Income (GNI)
GNI per capita, adjusted for purchasing power parity, comes from the World Development Indicators Database. Data are available in the World Bank Climate Change Knowledge Portal (CCKP), an online tool that provides access to comprehensive global, regional, and country data on to climate change and development as well as various synthesis products.
AirCounts Additional Data
These data are used to calculate the economic benefits from PM2.5 for each city but cannot be viewed directly in the website.
The intake fraction is the fraction of a pollutant emitted from a source that is inhaled by a specified population. City-specific intake fractions were provided by Joshua Apte, Ph.D. student in the Energy and Resources Group at the University of California, Berkeley, based on the method described in:
Apte, Joshua, Emilie Bombrun, Julian Marshall, and William Nazaroff. 2012a. Global Intraurban Intake Fractions for Primary Air Pollutants from Vehicles and Other Distributed Sources. Environmental Science and Technology.
Value of a Statistical Life (VSL)
The U.S. Environmental Protection Agency's 1990 VSL estimate of $4.8 million was updated to $8.92 million in 2010 dollars using the U.S. Bureau of Labor Statistics' Consumer Price Index (CPI) and adjusting for income growth between 1990 and 2010.
The U.S.-based VSL was transferred to other countries based on the ratio of the country's per capita income to that of the U.S. using methods described in:
Hammitt, James K. and Robinson, Lisa A. 2011.The Income Elasticity of the Value per Statistical Life: Transferring Estimates between High and Low Income Populations. Journal of Benefit-Cost Analysis: Vol. 2: Iss. 1, Article 1. DOI: 10.2202/2152-2812.1009
Concentration-Response (C-R) Function
A C-R function describes the relationship between a pollutant concentration and a health effect. AirCounts uses a C-R function that relates ambient PM2.5 concentration and adult mortality derived from:
Krewski, D., M. Jerrett, R. Burnett et al. 2009. Extended Follow-Up and Spatial analysis of the American Cancer Society Linking Particulate Air Pollution and Mortality. Health Effects Institute, Cambridge MA.
In some locations ambient PM2.5 concentrations were higher than the range observed in the above referenced American Cancer Society study conducted in the U.S. To account for this, we adjust the C-R function following:
Ostro, B. 2004. Outdoor air pollution: Assessing the environmental burden of disease at national and local levels. World Health Organization, Geneva.