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Table 2 Prevalence and odds ratios (and 95% CI) of current wheezing by distance-based and emissions-based indicators of exposure before and after adjusting for person-based risk factors and co-morbidity as well as intra-school correlation in multivariable logistic models

From: Residential exposure to motor vehicle emissions and the risk of wheezing among 7-8 year-old schoolchildren: a city-wide cross-sectional study in Nicosia, Cyprus

 

N

Prevalence %

Unadjusted (N = 1675)

Adjusted1 (N = 1650)

Adjusted2 (N = 1461)

A. Distance-based indicators

     

1. By proximity

> 300 m

622

9.0

1.00

1.00

1.00

 

150-300 m

413

9.0

0.99 (0.62,1.59)

0.93 (0.57,1.54)

0.89 (0.52,1.50)

 

100-150 m

195

8.6

0.97 (0.53,1.76)

0.89 (0.47,1.68)

1.01 (0.51,2.00)

 

50-100 m

207

8.7

0.96 (0.55,1.67)

0.94 (0.54,1.63)

1.08 (0.61,89)

 

< 50 m

238

11.7

1.35 (0.95,1.91)

1.27 (0.89,1.80)

1.30 (0.86,1.97)

2. Within 50 m of a main road

No

1437

8.9

1.00

1.00

1.00

 

Yes

238

11.7

1.36 (1.05,1.78)

1.32 (1.00,1.74)

1.33 (0.93,1.89)

3. Within 50 m of a road, stratified by levels of PM

No

1437

8.9

1.00

1.00

1.00

 

Yes, Low PM

148

10.1

1.15 (0.79,1.68)

1.10 (0.76,1.58)

1.10 (0.76,1.58)

 

Yes, High PM

90

14.4

1.73 (1.06,2.81)

1.72 (1.04,2.84)

1.72 (0.92,3.20)

4. Within 50 m of a road, stratified by levels of NOx

No

1437

8.9

1.00

1.00

1.00

 

Yes, Low NOx

126

11.8

1.38 (0.94,2.03)

1.31 (0.90,1.91)

1.31 (0.88,1.93)

 

Yes, High NOx

112

11.6

1.34 (0.82,2.20)

1.33 (0.81,2.21)

1.35 (0.75,2.43)

B. Distance-weighted emissions-indicators 3

1. PM at nearest street (kg/km per day)

None

622

9.0

1.00

1.00

1.00

 

Lowest (< 0.5)

748

8.8

0.98 (0.68,1.41)

0.92 (0.63,1.35)

0.97 (0.67,1.41)

 

Medium (0.5-1)

215

9.7

1.09 (0.72,1.66)

1.02 (0.68,1.54)

1.05 (0.67,1.65)

 

Highest (> 1)

90

14.4

1.71 (1.00,2.90)

1.65 (0.96,2.81)

1.67 (0.82,3.38)

 

P-value for trend

 

0.12

0.22

0.26

2. PM at street with highest levels (kg/km per day)

None

622

9.0

1.00

1.00

1.00

 

Lowest (< 0.5)

757

8.7

0.97 (0.67,1.39)

0.91 (0.62,1.33)

0.95 (0.65,1.37)

 

Medium (0.5-1)

202

10.3

1.17 (0.77,1.78)

1.09 (0.72,1.65)

1.13 (0.72,1.75)

 

Highest (> 1)

94

13.8

1.62 (0.96,2.75)

1.57 (0.92,2.67)

1.65 (0.84,3.25)

 

P-value for trend

 

0.11

0.20

0.20

3. NOx at nearest street (kg/km per day)

None

622

9.0

1.00

1.00

1.00

 

Lowest (< 10)

725

8.5

0.95 (0.64,1.39)

0.89 (0.59,1.33)

0.92 (0.62,1.37)

 

Medium (10-20)

230

11.6

1.34 (0.88,2.06)

1.27 (0.83,1.95)

1.35 (0.85,2.14)

 

Highest (> 20)

98

11.2

1.28 (0.74,2.20)

1.23 (0.71,2.14)

1.19 (0.58,2.47)

 

P-value for trend

 

0.19

0.31

0.31

4. NOx at street with highest levels (kg/km per day)

None

622

9.0

1.00

1.00

1.00

 

Lowest (< 10)

813

9.7

1.09 (0.78,1.53)

1.02 (0.72,1.46)

1.08 (0.76,1.53)

 

Medium (10-20)

135

6.6

0.72 (0.36,1.47)

0.70 (0.35,1.41)

0.71 (0.32,1.59)

 

Highest (> 20)

105

11.4

1.30 (0.76,2.25)

1.23 (0.70,2.18)

1.21 (0.61,2.42)

 

P-value for trend

 

0.75

0.94

0.91

  1. 1Adjusted for gender and smoking during pregnancy, 2Also adjusting for co-morbidity (i.e. eczema, hay fever and family history of atopy) and all other risk factors except birthweight, 3 Cut-off points for levels of exposure were defined based on the 50% and 75% (i.e. highest quartile) of the distribution of non-zero values.