Abstract
Interquartile contrasts make environmental associations easier to describe, but they do not create a common physical exposure across measurement bands or averaging windows. This article audits daily exposure summaries published in a study of particulate matter gamma activity and biomarkers in people with chronic obstructive pulmonary disease. We extract the first and third quartiles for seven ambient and seven estimated indoor gamma-activity measures and calculate their interquartile ranges. Indoor-to-ambient range ratios vary from 0.631 to 0.714. The range for ambient gamma band 3 is approximately 76 times that for band 9, illustrating the importance of the underlying measurement scale. These are descriptive transformations of published daily summaries. They are not patient-level analyses, absorbed-dose estimates, or reconstructed seven-day biomarker effects. We use the audit to distinguish exposure standardization, repeated-visit inference, multiplicity, and causal interpretation. A reproducible summary-table analysis can clarify what a reported contrast means without claiming access to unavailable clinical records. Keywords: COPD; gamma activity; interquartile range; exposure standardization; repeated measures; secondary analysis.
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Copyright (c) 2026 Cole Richardson, Ian Matthews, Grant Douglas (Author)