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Table 2 Associations of PM2.5 and O3 with breast density

From: Association between air pollution and mammographic breast density in the Breast Cancer Surveilance Consortium

Exposure BI-RADS I OR (95% CI) BI-RADS III OR (95% CI) BI-RADS IV OR (95% CI)
PM2.5 quartile (median, ug/m3)a
 1st (7.18) Referent Referent Referent
 2nd (8.44) 0.95 (0.92–0.98) 1.08 (1.05–1.11) 0.90 (0.86–0.94)
 3rd (9.27) 0.85 (0.81–0.88) 1.19 (1.16–1.22) 1.00 (0.95–1.05)
 4th (10.68) 0.88 (0.85–0.92) 1.19 (1.16–1.23) 0.97 (0.92–1.02)
P for trend <0.0001 <0.0001 <0.0001
Continuous PM2.5 0.98 (0.97–0.99) 1.04 (1.03–1.04) 1.00 (0.99–1.01)
O3 quartile (median, ppb)a
 1st (28.48) Referent Referent Referent
 2nd (32.94) 0.86 (0.81–0.90) 1.13 (1.10–1.16) 1.08 (1.03–1.14)
 3rd (37.03) 0.85 (0.79–0.91) 1.11 (1.07–1.16) 0.99 (0.92–1.07)
 4th (39.05) 1.12 (1.04–1.20) 0.98 (0.94–1.03) 0.80 (0.73–0.87)
P for trend <0.0001 <0.0001 <0.0001
Continuous O3 1.02 (1.01–1.03) 1.00 (1.00–1.01) 0.97 (0.96–0.98)
  1. For breast density, American College of Radiology’s Breast Imaging-Reporting and Data System (BI-RADS) II (scattered fibroglandular densities) is the reference category; risk estimates are adjusted for age at mammogram, body mass index at mammogram, race, study site, age at menarche, parity and age at first birth, menopausal status/hormone use, family history of breast cancer, history of breast biopsy, and median household income for the zip code. aQuartiles defined as <7.91, 7.91 to <8.81, 8.81 to <9.86, and ≥9.86 ug/m3 for particulate matter <2.5 μm in diameter (PM2.5) and <29.73, 29.73 to <36.05, 36.05 to <37.92 and ≥37.92 ppb for ozone (O3)
  2. CI confidence interval, HRT hormone replacement therapy, OR odds ratio. Note: BI-RADS II is the reference group