Air Pollution Exposure Model for Individuals (EMI) in Health Studies: Evaluation for Ambient PM_(2.5) in Central North Carolina

摘要

Air pollution health studies of fine particulate matter (diameter ＜2.5 μm, PM_(2.5)) often use outdoor concentrations as exposure surrogates. Failure to account for variability of indoor infiltration of ambient PM_(2.5) and time indoors can induce exposure errors. We developed and evaluated an exposure model for individuals (EMI), which predicts five tiers of individual-level exposure metrics for ambient PM_(2.5) using outdoor concentrations, questionnaires, weather, and time-location information. We linked a mechanistic air exchange rate (AER) model to a mass-balance PM_(2.5) infiltration model to predict residential AER (Tier 1), infiltration factors (Tier 2), indoor concentrations (Tier 3), personal exposure factors (Tier 4), and personal exposures (Tier 5) for ambient PM_(2.5). Using cross-validation, individual predictions were compared to 591 daily measurements from 31 homes (Tiers 1-3) and participants (Tiers 4-5) in central North Carolina. Median absolute differences were 39% (0.17 h~(-1)) for Tier 1, 18% (0.10) for Tier 2, 20% (2.0 μg/ m~3) for Tier 3, 18% (0.10) for Tier 4, and 20% (1.8 μg/m~3) for Tier 5. The capability of EMI could help reduce the uncertainty of ambient PM_(2.5) exposure metrics used in health studies.