Table 4

Subgroup analysis on effects of changes in long-term air pollution (annual average) concentrations on changes in FeNO levels adjusted for changes in short-term concentrations*

Modifying factor (N)NO2PM2.5PM10O3
Asthma
 No Asthma–No Asthma (1052)2.2 (0.22, 4.12)†5.3 (1.68, 8.83)‡0.1 (−2.07, 2.24)−0.5 (−4.24, 3.30)
 No Asthma–Asthma (23)3.1 (−2.38, 8.64)1.8 (−9.1, 12.65)−4.6 (−9.76, 0.65)−2.7 (−10.79, 5.33)
 Asthma–Asthma (136)2.8 (0.32, 5.31)†3.5 (−1.272, 8.28)0.6 (−2.14, 3.264)−2.31 (−7.31, 2.71)
 Interaction p value0.750.550.140.53
Allergy
 No Allergy–No Allergy (441)2.3 (0.32, 4.46)†5.0 (1.20, 8.78)‡0.7 (−1.60, 3.09)−1.0 (−5.04, 2.98)
 No Allergy–Allergy (44)1.1 (−2.83, 5.02)4.7 (−2.54, 12.02)1.2 (−3.60, 5.98)0.9 (−5.06, 6.78)
 Allergy–Allergy (726)2.2 (0.23, 4.28)†4.9 (1.25, 8.62)‡−0.1 (−2.35, 2.04)−0.756 (−4.60, 3.09)
 Interaction p value0.780.990.410.77
Season
 Warm–Warm (226)2.0 (−0.50, 4.50)6.9 (1.90, 11.86)‡−0.2 (−2.79, 2.38)1.1 (−4.03, 6.22)
 Cold–Warm (368)2.4 (−0.90, 5.74)3.4 (−0.77, 7.66)0.5 (−2.7, 3.74)−0.7 (−5.92, 5.59)
 Warm–Cold (213)3.1 (0.36, 5.81)†11.8 (3.22, 20.30)‡0.4 (−2.55, 3.30)3.3 (−3.80, 10.58)
 Cold–Cold (404)2.8 (−1.15, 6.71)4.5 (−0.48, 9.41)0.6 (−3.03, 4.15)−0.6 (−5.59, 4.41)
 Interaction p value0.820.080.900.63
Gender
 Boys (571)2.5 (0.41, 4.67)†4.2 (0.46, 7.94)‡0.1 (−2.14, 2.28)−1.6 (−5.52, 2.40)
 Girls (640)2.2 (0.22, 4.14)†5.7 (1.94, 9.41)‡0.2 (−2.07, 2.45)−0.1 (−3.99, 3.72)
 Interaction p value0.590.240.870.22
  • *Results are scaled to the IQR values of 1.8 ppb (NO2), 2.4 μg/m3 (PM2.5), 3.4 μg/m3 (PM10) and 2.1 ppb (O3) of changes in annual average pollution levels between the two years of study. Estimates are adjusted for short-term effects of the same air pollutant. Models are also adjusted, as appropriate, for changes (or interactions with changes in age for time-independent covariates) in community, race/ethnicity, sex, asthma, asthma medication use, history of respiratory allergy, age, day of FeNO collection and season.

  • †p<0.05.

  • ‡p<0.01.