EPA’s BenMAP tool helps evaluate air pollution policy health effects

Feb 7, 2017

Tools and data from the Environmental Protection Agency are essential to maintaining healthy air quality in North Carolina, especially as our population continues its rapid growth, the climate continues to change and our understanding of the health impacts of various pollutants increases.

Last year, the US Global Climate Change Research Program released a health assessment that showed how both eastern and western North Carolina will face heightened risks for wildfires.

Around the same time, the American Thoracic Society found troubling mortality and morbidity rates from exposure to air pollution lower than current standards.

Earlier this decade, advocates concerned about a proposed cement plant in Castle Hayne, North Carolina, commissioned a study which found that the plant’s emissions would cause 850 new cases of acute respiratory disease among people residing in the surrounding three counties over a five-month period, at a total cost ranging from $6.3 to $6.6 million.

These three assessments relied on an EPA-developed tool, BenMAP (Benefits Mapping and Analysis Program). BenMAP can show policymakers how many air pollution related deaths/illnesses could be prevented (or caused), and how much money the public could save (or spend) from improving (or damaging) the air quality. This tool helps policy makers to compare against the cost of a policy, decide between different policies, improve efficiency and effectiveness, and help determine if a particular policy is worth it to society, according to Neal Fann, an EPA policy analyst who is one of the developers of BenMAP.

What information we can get from BenMAP?

BenMAP quantifies the health impacts of particulate matters and ozone, including the aggravated asthma, premature deaths, and non-fatal heart attacks, lost days of schools. For economic impacts, it summarizes the “cost of illness” ( the medical expenses and lost work that an individual must bear for air pollution-related hospital admissions, visits to the emergency department and other outcomes) and “willingness to pay” (the direct costs noted above as well as the value that individuals place on pain and suffering, loss of satisfaction and leisure time).

How do we use BenMAP? 

The Community Edition of BenMAP, BenMAP-CE, is free and easy for beginners to use. However, in order to better understand the formulas and terminology in BenMAP-CE, having some statistical and analytical knowledge is recommended. You could learn using BenMAP-CE in three ways: follow the user’s manual step by step from installing the software to operating the tool for various uses; conducting self-paced training using the online interactive modules; or attending in-person trainings under the guidance of an instructor. The EPA also provides a number of studies developed with BenMAP.

Before using BenMAP, you need to obtain data for estimating the health and economic impacts. You can select your population of interest (e.g., age, race), health outcome (e.g., asthma, cardiovascular disease), and economic data (e.g., medical costs, cost due to lost workdays) from BenMAP’s built-in database. The only data you need to obtain is the air quality data such as concentrations of particulate matter, which you can easily download from EPA’s website. After loading the data into the BenMAP software, you can follow the three steps to estimate health and economic impacts (also shown in Figure 1).

  1. Generate Air Quality Surfaces, also known as the air quality change. This is the difference between the baseline air pollution level and the air pollution level after some change such as a new regulation.
  2. Estimate Health effects. BenMAP estimates the health effects based on the function, Health Effect = Air Quality Change * Health Effect Estimate * Exposed Population * Health Baseline Incidence. Below is the explanation of each term in this function:

Exposed Population is the number of people affected by the air pollution reduction. Health Effect Estimates is the percentage change in the risk of an adverse health effect due to a one unit change in air pollution. Health Baseline Incidence is the average number of people who die or suffer in a given population over a given period of time at the starting air pollution level.

  1. Aggregation, pooling and valuation-monetize health effects. You can calculate the economic value of health effects by multiplying the reduced/increased health effect by an estimate of the economic value per case: Economic Value = Health Effect * Value of Health Effect

There are several different ways of calculating the value of the health effect.  For example, the value of an avoided premature mortality is generally calculated using the monetary value that a group of people are willing to pay to slightly reduce the risk of premature death in the population. For other health effects, the medical costs of the illness may be the only valuation data available. The BenMAP-CE database includes several different functions for calculating the value of health effects.

Fig 1. Three steps of using BenMAP

There are three different kinds of results that you can get from BenMAP: tabular formats, maps, and audit trails. Below we explain these results in detail:

  1. Tabular format: All the data can be stored in rows and columns. The results can be downloaded into spreadsheet and database programs. Below is an example of a tabular format result.
  2. Map: All the data can be displayed in a map. You can add various layers of data such as air pollutant level and health impacts. Below is an example of a mapped result.
  3. Audit trail report: the audit trail report provides a summary of the options selected in the steps. You can easily find information such as the functions you use and data information in the audit trail report. Below is an example of an audit trail report.

Government plays an important role not only in gathering data, but also in creating tools that help us understand the significance of that data to our health. These tools are essential for helping us advocate for policies that will protect our health today and in the future.


Guest Post Contributed by Yan Jin, MSEE