Table 2.

Adjusted OR (95% CIs) from the single-pollutant logistic regression models for ACPA positivity

Exposure variable	Positivity: ≥60 units/ml (N positive = 134)	Positivity: ≥40 units/ml (N positive = 292)	Positivity: ≥20 units/ml (N positive = 786)
Industrial SO2	1.03 (0.98–1.08)	1.03 (1.00–1.07)*	1.03 (1.00–1.06)*
Industrial NO2	0.90 (0.63–1.28)	1.14 (0.91–1.41)*	1.01 (0.86–1.17)*
Industrial PM2.5	1.17 (0.92–1.48)	1.21 (1.02–1.42)	1.19 (1.04–1.36)
Overall PM2.5	0.94 (0.89–1.01)	0.95 (0.91–1.01)	0.98 (0.95–1.01)

Adjusted ORs (95% CI) for industrial SO₂ and NO₂ are per 1 ppb increase while they are reported per 1 μg/m³ increase for regional and overall PM_2.5 levels. Variables adjusted for include age, sex, ancestry, smoking, and annual income level. *Statistically significant associations include industrial PM_2.5 (where 95% CIs exclude the null value) and industrial SO₂ (where 95% CIs just barely include the null value)