Table 3 Association between incidence of asthma and change in traffic-related PM₁₀ and other PM₁₀ variables among SAPALDIA never-smokers (two-pollutant models)

Co-pollutant	Single-pollutant model	Two-pollutant model
Co-pollutant	Single-pollutant model	HR for dTPM₁₀	HR for co-pollutant
Change in traffic-related PM₁₀ (dTPM₁₀)	1.30 (1.05 to 1.61)	1.30 (1.05 to 1.61)	N/A
Change in regional PM₁₀	1.10 (0.94 to 1.30)	1.28 (1.00 to 1.64)	1.02 (0.86 to 1.21)
Change in secondary PM₁₀	1.44 (0.89 to 2.33)	1.30 (0.98 to 1.71)	1.00 (0.53 to 1.92)
Change in total PM₁₀	1.07 (1.00 to 1.14)	1.22 (0.88 to 1.71)	1.02 (0.93 to 1.13)
Level of traffic-related PM₁₀ at SAPALDIA 1	0.80 (0.64 to 1.00)	1.22 (0.93 to 1.59)	0.87 (0.68 to 1.11)

PM₁₀, particulate matter up to 10 μm in diameter.
Hazard ratios (HR) and 95% CI are given per 1 μg/m³ and based on single-pollutant and two-pollutant models, adjusted for age, gender, baseline atopy, body mass index, bronchial hyperreactivity, maternal allergies (main model of table 2). All models include 2390 subjects and 34 new cases of asthma.
Total PM₁₀ is the sum of all PM₁₀ and thus includes traffic-related PM₁₀.