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Development of the PEARLS Model (Particulate Exposure from Ambient to Regional Lung by Subgroup) and Use of Monte Carlo Simulation to Predict Internal Exposure to PM 2.5 in Toronto 1
Author(s) -
Gower Stephanie K.,
McColl Stephen
Publication year - 2005
Publication title -
risk analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.972
H-Index - 130
eISSN - 1539-6924
pISSN - 0272-4332
DOI - 10.1111/j.1539-6924.2005.00591.x
Subject(s) - aerodynamic diameter , particulates , population , demography , monte carlo method , subgroup analysis , exposure assessment , environmental health , medicine , environmental science , air pollution , statistics , atmospheric sciences , mathematics , chemistry , physics , confidence interval , organic chemistry , sociology
Air pollution is a current and growing concern for Canadians, and there is evidence that ambient levels that meet current exposure standards may be associated with mortality and morbidity in Toronto, Canada. Evaluating exposure is an important step in understanding the relationship between particulate matter (PM) exposure and health outcomes. This report describes the PEARLS model (Particulate Exposure from Ambient to Regional Lung by Subgroup), which predicts exposure distributions for 11 age‐gender population subgroups in Toronto to PM 2.5 (PM with a median aerodynamic diameter of 2.5 μm or less) using Monte Carlo simulation techniques. The model uses physiological and activity pattern characteristics of each subgroup to determine region‐specific lung exposure to PM 2.5 , which is defined as the mass of PM 2.5 deposited per unit time to each of five lung regions (two extrathoracic, bronchial, bronchiolar, and alveolar). The modeling results predict that children, toddlers, and infants have the broadest distributions of exposure, and the greatest chance of experiencing extreme exposures in the alveolar region of the lung. Importance analysis indicates that the most influential model variables are air exchange rate into indoor environments, time spent outdoors, and time spent at high activity levels. Additionally, a “critical point” was defined and introduced to the PEARLS to investigate the effects of possible threshold‐pathogenic phenomena on subgroup exposure patterns. The analysis indicates that the subgroups initially predicted to be most highly exposed were likely to have the highest proportion of their population exposed above the critical point. Substantial exposures above the critical point were predicted in all subgroups for ambient concentrations of PM 2.5 commonly observed in Toronto after continuous exposure of 24 hours or more.