Table 3 Incidence rate (IR) with 95% CI of new onset asthma stratified by community-specific annual average PM_2.5 (and other non-ozone pollutant) levels (1994–2001)*

Lung function	Low PM_2.5	High PM_2.5
Lung function	IR (95% CI)†	IR (95% CI)†
FVC (% predicted)
⩽90	19.4 (7.5 to 50.5)	14.2 (5.1 to 39.6)
90–110	16.8 (7.0 to 40.1)	25.6 (11.1 to 59.2)
>110	7.9 (2.9 to 21.9)	16.7 (6.5 to 42.9)
FEV₁ (% predicted)
⩽90	23.7 (9.4 to 59.4)	20.8 (8.0 to 54.0)
90–110	15.6 (6.5 to 37.4)	23.1 (10.0 to 53.7)
>110	6.5 (2.3 to 18.7)	18.8 (7.5 to 47.3)
FEF_25–75 (% predicted)
80–100	21.1 (8.8 to 50.5)	23.8 (10.2 to 55.6)
100–120	11.9 (4.7 to 30.0)	23.9 (9.9 to 57.7)
⩾120	6.4 (2.3 to 18.2)	15.9 (6.3 to 40.5)
Overall IR (95% CI)	14.2 (7.0 to 28.7)	18.4 (9.4 to 35.9)

FVC, forced vital capacity; FEV₁, forced expiratory volume in 1 s; FEF_25–75, forced expiratory flow over the mid-range of expiration; PM_2.5, particulate matter with an aerodynamic diameter of <2.5 μm.
*The 12 communities were grouped by annual PM_2.5 level into six high (13.7–29.5 μg/m³) and six low (5.7–8.5 μg/m³) communities. However, the same grouping and estimates would occur if the communities were grouped by NO₂, PM₁₀, acids, elemental carbon or organic carbon.
†Adjusted incidence rate of newly diagnosed asthma (per 1000 person-years) for different categories of lung function is reported by high and low PM_2.5 (non-ozone pollutant) communities, adjusted for community, sex and race/ethnicity.