SUPPLEMENTARY MATERIAL
COHORT DESCRIPTIONS
The Canadian Asthma Primary Prevention Study (CAPPS) is a prospective, randomized controlled study with follow-up to the age of 7 years. 545 high-risk infants were randomized prior to birth in the study centers of Vancouver and Winnipeg, Canada.
High-risk was defined as having one first-degree relative with asthma or two first-degree relatives with other IgE mediated diseases. The multifaceted intervention included education and counseling on the risk factors of asthma, specifically dust mite and environmental tobacco smoke avoidance, and breastfeeding support. Parents completed questionnaires on respiratory symptoms and physician diagnoses at 1, 2 and 7 years. At 7 years children were examined by a pediatric allergist blinded to intervention status and questionnaire responses; and peripheral blood was obtained from children and their parents. Asthma was defined from questionnaires as at least two of more distinct episodes of cough (each lasting a minimum of 2 weeks), at least two distinct episodes of wheeze
(each lasting a minimum of 1 week), plus at least one of the following: nocturnal cough at least once per week (in absence of a cold), hyperpnoea-induced cough or wheeze at any time, or response to treatment with

-agonist and/or anti-inflammatory drugs [1, 2].
DNA was genotyped by the Illumina BeadArray system (Illumina, San Diego, California,
USA) following the manufacturer’s protocol.

The Study of Asthma, Genetics and Environment (SAGE) is a population-based birth cohort. Children were identified for inclusion from a provincial healthcare registry. The study included all 13,980 children born in the province of Manitoba in 1995 with continued residence in the province through 2002. Surveys were sent to each family when children were 7 years old and, from the 3,598 responders, 723 children were selected for a nested case-control study of asthma (246 asthmatics; 477 controls). Children living in rural areas, low-income neighborhoods and First Nations communities were oversampled. At mean age of 9 years, children were examined by a pediatric allergist for allergic diseases, including asthma, and symptoms. Blood and buccal samples were collected and DNA was genotyped using the Illumina BeadArray system (Illumina, San
Diego, California, USA) [3].
The Children, Allergy, Milieu, Stockholm, Epidemiological Survey (BAMSE) is a population based prospective birth cohort study with follow-up through the age of 16.
Between February 1994 and November 1996 newborns were recruited at their first child health visit in predefined areas of Stockholm, Sweden (n=4,089). Infants were excluded if their family was planning to move during the first year of life, an older sibling was already enrolled, serious illness during the neonatal period or parents had insufficient knowledge of Swedish. Parental questionnaires were used to assess physician diagnosed asthma, allergic rhinitis and eczema; and episodes of wheezing at ages 1, 2, 4 and 8 years[4, 5]. At 4 years of age 2,298 children provided blood samples and a sub-sample of this group was used to populate a nested case-control study of wheeze (497 wheezers;
485 randomly selected controls) [6]. DNA was genotyped using matrix-assisted laser

desorption/ionization–time of flight (MALDI-TOF) mass spectrometry (Sequenom, San
Diego, CA, USA).
The German infant study on the influence of nutrition intervention plus environmental and genetic influences on allergy development (GINIplus) is a population based prospective birth cohort, with an intervention component and follow-up to the age of 15 years. Between September 1995-June 1998 parents attending one of 18 maternity hospitals in the cities of Munich or Wesel were invited to participate. A total of 5,991 healthy full-term newborns whose parents were fluent in German were recruited. A subgroup of 2,252 infants with at least one atopic parent or sibling were assigned to the intervention group and randomly allocated to one of four study formulas if their parents chose not to breastfeed. Parental questionnaires were used to assess physician diagnosed asthma, allergic rhinitis and eczema; and episodes of wheezing at ages 1, 2, 3, 4, 6 and 10 years [7]. Clinical examinations and blood samples for DNA extraction were obtained at
6 and 10 years.
The influence of life style factors on the development of the immune system and allergies in East and West Germany plus the influence of traffic emissions and genetics
(LISAplus) study is a population based prospective birth cohort study with follow-up to the age of 15 years. Between December 1997-January 1999 parents attending one of 14 obstetrical clinics or hospitals throughout the cities of Munich, Leipzig, Wesel or Bad
Honnef were invited to participate. A total of 3,095 healthy full term newborns whose

parents were born in Germany and had German citizenship were recruited. Parental questionnaires were used to assess physician diagnosed asthma, allergic rhinitis and eczema; and episodes of wheezing at ages 0.5, 1, 1.5, 2, 4, 6 and 10 years [7]. Clinical examinations and blood samples for DNA extraction were obtained at 6 and 10 years.
For GINI and LISA, GSTP1 rs1695 and rs1138272 polymorphisms were detected using the restriction fragment length polymorphism approach [8] and high-resolution melting-
PCR using LightSNiP hybridization probe (TIB MolBiol, Berlin, Germany), respectively.
Remaining SNPs were genotyped using the iPLEX (Sequenom, San Diego, CA, USA) method by means of matrix assisted laser desorption ionization time of flight mass spectrometry method (MALDI-TOF MS, Mass Array; Sequenom, San Diego, CA, USA) in one laboratory according to the manufacturer’s instructions. Standard genotyping quality control included 10% duplicate and negative samples. Genotyping discordance rate was below 0.3%.
The Prevention and Incidence of Asthma and Mite Allergy (PIAMA) study is a population based prospective birth cohort study, with an intervention component, and follow-up through the age of 15 years. Between May 1996 – December 1997, 3963 children were born to mothers who had been recruited during their first trimester of pregnancy from midwife practices in three different regions of The Netherlands. Children were divided into high- and low-risk groups based on a screening questionnaire on allergic disease of their mother. Children in the high-risk group were initially assigned to

the intervention arm (n=855) with a random subset allocated to the natural history arm
(n=472) with low-risk children. The intervention required use of a mite-impermeable mattress and pillow cover [9]. Information on physician-diagnosed asthma, allergic rhinitis and eczema; and episodes of wheezing were ascertained through parental questionnaires completed at each birthday until 8 years. Blood samples were collected at
4, 8, 11 and 12 years. DNA was extracted from buccal swabs or blood collected at 4 or 8 years. Competitive Allele-Specific PCR using KASParTM genotyping chemistry was used for genotyping (K-Biosciences, Herts, UK).
CASE DEFINITIONS
Asthma Allergic Rhinitis
CAPPS Clinical exam by a pediatric allergist
Clinical exam by a pediatric allergist
SAGE Parent report of Parent report of physician physician diagnosed diagnosed allergic rhinitis,
Eczema
Parental questionnaire assessing physician diagnosed eczema
Parental questionnaire

asthma, confirmed by pediatric allergist confirmed by pediatric allergist assessing physician diagnosed eczema
BAMSE Parental questionnaire
Parental questionnaire assessing symptoms (sneezing, runny or assessing physician blocked nose, itchy, red and diagnosed asthma
Parental questionnaire assessing watery eyes) after exposure to physician furred pets or pollen or a medical diagnosed eczema diagnosis of allergic rhinitis**
GINI Parental questionnaire
Parental questionnaire assessing physician diagnosed allergic assessing physician rhinitis or hay fever diagnosed asthma
Parental questionnaire assessing physician diagnosed eczema
LISA Parental questionnaire
Parental questionnaire assessing physician diagnosed allergic assessing physician rhinitis or hay fever diagnosed asthma
Parental questionnaire assessing physician diagnosed eczema
PIAMA Parental questionnaire
Parental questionnaire assessing sneezing, runny/blocked nose
Parental questionnaire

assessing physician diagnosed asthma
**Symptoms could have occurred anytime between the age of 4-8 years. assessing physician diagnosed eczema
REFERENCES
[1] Carlsten C, Dybuncio A, Becker A, Chan-Yeung M, Brauer M. Traffic-related air pollution and incident asthma in a high-risk birth cohort. Occup Environ Med. 2011
Apr;68(4):291-5.
[2] Chan-Yeung M, Manfreda J, Dimich-Ward H, Ferguson A, Watson W, Becker A. A randomized controlled study on the effectiveness of a multifaceted intervention program in the primary prevention of asthma in high-risk infants. Arch Pediatr
Adolesc Med. 2000 Jul;154(7):657-63.
[3] Kozyrskyj AL, HayGlass KT, Sandford AJ, Pare PD, Chan-Yeung M, Becker AB. A novel study design to investigate the early-life origins of asthma in children (SAGE study). Allergy. 2009 Aug;64(8):1185-93.
[4] Nordling E, Berglind N, Melen E, Emenius G, Hallberg J, Nyberg F, et al. Trafficrelated air pollution and childhood respiratory symptoms, function and allergies.
Epidemiology. 2008 May;19(3):401-8.

[5] Wickman M, Kull I, Pershagen G, Nordvall SL. The BAMSE project: presentation of a prospective longitudinal birth cohort study. Pediatr Allergy Immunol. 2002;13
Suppl 15:11-3.
[6] Melén E, Nyberg F, Lindgren CM, Berglind N, Zucchelli M, Nordling E, et al.
Interactions between glutathione S-transferase P1, tumor necrosis factor, and trafficrelated air pollution for development of childhood allergic disease. Environ Health
Perspect. 2008 Aug;116(8):1077-84.
[7] Gehring U, Cyrys J, Sedlmeir G, Brunekreef B, Bellander T, Fischer P, et al. Trafficrelated air pollution and respiratory health during the first 2 yrs of life. Eur Respir J.
2002 Apr;19(4):690-8.
[8] Slama R, Grabsch C, Lepeule J, Siroux V, Cyrys J, Sausenthaler S, et al. Maternal fine particulate matter exposure, polymorphism in xenobiotic-metabolizing genes and offspring birth weight. Reprod Toxicol. 2010 Dec;30(4):600-12.
[9] Koopman LP, van Strien RT, Kerkhof M, Wijga A, Smit HA, de Jongste JC, et al.
Placebo-controlled trial of house dust mite-impermeable mattress covers: effect on symptoms in early childhood. Am J Respir Crit Care Med. 2002 Aug 1;166(3):307-
13.

SUPPLEMENTARY MATERIAL
TABLE 1. Summary statistics for each pollutant by city.
NO
2
(µg/m 3 ) PM
2.5
(µg/m 3 )
PM
2.5 absorbance
(µg/m 3
)
O
3
(µg/m 3 )
M ea n
M
S Me Ra
D dian nge ea n
S Me Ra
D dian nge
M ea n
S Me Ra
D dian nge
M ea n
S Me Ra
D dian nge
Pooled
7
24.
.
0
4
0-
24.
2
66.
9
15.
5
3
.
0
00
15.
6
25.
1.7 .
2 4
13.
039.
1.7
5.0 2
6
.
9
40.
2
3-
59.
7
CAPPS
Vanco
5 uver 32.
.
6
9
32.
2
18.
9-
55.
2
2
5.7 .
6
13.
0-
5.2 10.
1.6
0
1
.
2
1.0
2
021.
5.0
.
3
9
20.
1
5-
27.
0
Winni peg
4.1
4
12.
.
0
0
12.
3 21.
-
5
- - - - - - - - - - - -

SAGE
BAMSE
Winni peg
4.1
3
12.
.
5
3
12.
2 21.
-
2
- - - - - - - - - - - -
Stockh
6 olm 27.
.
6
9
26.
9
2.2
54.
-
5
- - - - - - - - - - - -
Jarfall a
2.2
2
7.5 .
9
7.1
18.
-
0
- - - - - - - - - - - -
Solna 5.5
3
17.
.
6
8
17.
1 46.
-
5
- - - - - - - - - - - -
Sundb yberg
14.
2
4
.
13.
6.8
-
7
20.
- - - - - - - - - - - -

9 3
GINI
Munic h
6
27.
.
8
1
19.
26.
4
513.
66.
.
4
3
9
1
13.
1
11.
9-
21.
9
0
1.8 .
3
34.
1.7
1.4
-
4.3
4
45.
.
6
1
44.
6
1-
59.
7
Wesel 13.
3
24.
.
0
0
23.
9
9-
41.
4
- -
32.
- - 1.6
0
.
2
1.6
0.8
-
2.3
3
38.
.
2
8
38.
0
3-
54.
3
LISA
Munic h
6
27.
.
7
2
19.
26.
5
613.
64.
.
4
3
4
1
13.
1
12.
0-
21.
9
0
1.8 .
3
35.
1.7
1.4
-
4.4
4
46.
.
0
3
44.
7
5-
59.
3
Wesel 17.
2
24.
.
2
8
24.
1
8-
37.
1
- -
32.
- - 1.6
0
.
2
1.6
1.1
-
2.3
3
38.
.
2
9
38.
0
3-
49.
0
Leipzi
20.
3 18.
18.
- - - - - - - - 41. 1
41.
38.

g 8 .
4
8 5-
34.
8
8 .
6
7 0-
52.
9
Bad
Honne f
- - - - - - - - - - - - - - - -
PIAMA
Gronin gen
3
16.
.
8
8
12.
0
15.
8
614.
34.
.
5
9
9
14.
3
13.
5-
19.
2
0
1.3 .
2
20.
1.2
0.8
-
2.4
4
35.
.
0
9
34.
3
0-
45.
5
Rivm
3
28.
.
4
2
22.
27.
7
018.
49.
.
3
9
0
0
18.
2
16.
8-
24.
0
0
1.9 .
2
18.
1.9
1.5
-
3.3
3
31.
.
0
8
32.
0
9-
42.
6
Wagen
4 ingen 26.
.
5
6
21.
25.
1
118.
50.
.
1
2
9
1
17.
8
16.
8-
24.
6
0
1.9 .
3
15.
1.8
1.4
-
3.4
3
33.
.
5
8
33.
3
9-
45.
9
Rotter
31.
6
.
29.
22.
1-
17.
1
.
17.
15.
2.0
8-
0
.
1.9
1.4
-
34.
4
.
34.
13.
3-

dam 6 7 2 58.
4
7 5 2 25.
2
3 3.7 7 5 8 47.
7
Pollutant data are calculated as annual averages based on the home address reported at birth.
NO
2
data are based on traffic-related air pollution land use regression models for all cohorts except BAMSE where NO
2
is based on dispersion modeling.
PM
2.5
and PM
2.5
absorbance data are based on traffic-related air pollution land use regression models.
O
3
data are based on an atmosphere model.
SD - standard deviation.