Health Benefits Module
The Health Benefits Module is based on the Air Quality Benefits Assessment Tool (AQBAT) developed by Health Canada (Judek et al., 2012). The module starts by calculating the Baseline Counts (bch) for the pre-determined 18 health endpoints used in AQBAT and which are shown in the table below.
|HID||Health Endpoint h||Pollutant||Age|
|1||Acute Exposure Mortality||O3, SO2, NOX||All|
|2||Acute Respiratory Symptom Days||Acute PM25, O3||All|
|3||Adult Chronic Bronchitis Cases||Chronic PM25||25+|
|4||Asthma Symptom Days||Acute PM25, O3||All|
|5||Cardiac Emergency Room Visits||Acute PM25||All|
|6||Cardiac Hospital Admissions||Acute PM25||All|
|7||Child Acute Bronchitis Episodes||Chronic PM25||Under 20|
|8||Chronic Exposure Mortality||Chronic PM25||30+|
|9||Elderly Cardiac Hospital Admissions||CO||65+|
|10||Minor Restricted Activity Days||O3||All|
|11||Respiratory Emergency Room Visits||Acute PM25, O3||All|
|12||Respiratory Hospital Admissions||Acute PM25, O3||All|
|13||Restricted Activity Days||Acute PM25||20+|
|14||Chronic Exposure Cardiovascular Mortality||Chronic PM25||30+|
|15||Chronic Exposure Respiratory Mortality||Chronic PM25, O3||30+|
|16||Chronic Exposure Cerebrovascular Mortality||Chronic PM25||30+|
|17||Chronic Exposure Ischemic Heart Disease Mortality||Chronic PM25||30+|
|18||Chronic Exposure Lung Cancer Mortality||Chronic PM25||30+|
bch is calculated as the product of the rgi|h values and population size Kgi estimated by SMARTPLANS in each zone i, and then summed over all zones. The result is a vector of 18 bch values for the 18 health endpoints:
Next, pollution concentrations for pollutants p are obtained from the estimates generated by the Pollution Concentration Models for both the base case scenario r and alternative scenario a to calculate the average region-wide concentration Cp|r and Cp|a per pollutant p. The module then calculates the Concentration Risk Functions (CRFs) for pollutant p and health endpoint h as the percent excess (PctXShp) based on the calculated average concentrations. The CRF is formulated as either a linear or a Poisson function. If the CRF is linear, then:
On the other hand, if the CRF is Poisson, then:
where ω is the threshold per each pollutant and βCRF are the parameters for each health endpoint specified above.
The Health Benefit Module then calculates the life years gained (LYGhp) by using the slope values θhp:
The gross count (GChp) per pollutant p and corresponding health endpoints h for the following pollutants (PM2.5Chronic, PM2.5Acute, O3, SO2, NOx, and CO) are calculated as follows:
where αp is a pollution adjustment factor set to 0.4192 for O3 and 1 for all other pollutants. To avoid double counting, GChp values are adjusted for the health endpoints that overlaps with multiple pollutants. That is:
where h' and p' pertain to health endpoints and pollutants that overlap with health endpoints h and pollutants p.
The Netted Counts (NC) are then calculated as follows:
Lastly, the Dollar Valuation (DVhp) for the net count is estimated as follows:
where ρ is the monetary conversion factor value.
Judek, S., Stieb, D., Jovic, B., Edwards, B., 2012. Air Quality Benefits Assessment Tool (AQBAT) - User Guide. Health Canada - Healthy Environments and Consumer Safety Branch.