Respiratory symptoms in children living near busy roads and their relationship to vehicular traffic: results of an Italian multicenter study (SIDRIA 2).
BACKGROUND
Epidemiological studies have provided evidence that exposure to vehicular traffic increases the prevalence of respiratory symptoms and may exacerbate pre-existing asthma in children. Self-reported exposure to road traffic has been questioned as a reliable measurement of exposure to air pollutants. The aim of this study was to investigate whether there were specific effects of cars and trucks traffic on current asthma symptoms (i.e. wheezing) and cough or phlegm, and to examine the validity of self-reported traffic exposure.


METHODS
The survey was conducted in 2002 in 12 centers in Northern, Center and Southern Italy, different in size, climate, latitude and level of urbanization. Standardized questionnaires filled in by parents were used to collect information on health outcomes and exposure to traffic among 33,632 6-7 and 13-14 years old children and adolescents. Three questions on traffic exposure were asked: the traffic in the zone of residence, the frequency of truck and of car traffic in the street of residence. The presence of a possible response bias for the self-reported traffic was evaluated using external validation (comparison with measurements of traffic flow in the city of Turin) and internal validations (matching by census block, in the cities of Turin, Milan and Rome).


RESULTS
Overall traffic density was weakly associated with asthma symptoms but there was a stronger association with cough or phlegm (high traffic density OR = 1.24; 95% CI: 1.04, 1.49). Car and truck traffic were independently associated with cough or phlegm. The results of the external validation did not support the existence of a reporting bias for the observed associations, for all the self-reported traffic indicators examined. The internal validations showed that the observed association between traffic density in the zone of residence and respiratory symptoms did not appear to be explained by an over reporting of traffic by parents of symptomatic subjects.


CONCLUSIONS
Children living in zones with intense traffic are at higher risk for respiratory effects. Since population characteristics are specific, the results of validation of studies on self-reported traffic exposure can not be generalized.
Migliore
Enrica
E
Cancer Epidemiology Unit, AOU San Giovanni Battista Hospital-Center for Cancer Prevention (CPO Piedmont) and University of Turin, Via Santena 7, 10126 Turin, Italy. enrica.migliore@cpo.it
Berti
Giovanna
G
Galassi
Claudia
C
Pearce
Neil
N
Forastiere
Francesco
F
Calabrese
Roberto
R
Armenio
Lucio
L
Biggeri
Annibale
A
Bisanti
Luigi
L
Bugiani
Massimiliano
M
Cadum
Ennio
E
Chellini
Elisabetta
E
Dell'orco
Valerio
V
Giannella
Gabriele
G
Sestini
Piersante
P
Corbo
Giuseppe
G
Pistelli
Riccardo
R
Viegi
Giovanni
G
Ciccone
Giovannino
G
D000293:Adolescent; D000397:Air Pollution; D001249:Asthma / Q000453:epidemiology*; D001336:Automobiles / Q000706:statistics & numerical data; D002648:Child; D003371:Cough / Q000453:epidemiology; D005260:Female; D006801:Humans; D019570:Inhalation Exposure / Q000706:statistics & numerical data; D007558:Italy / Q000453:epidemiology; D008297:Male; D018986:Motor Vehicles / Q000706:statistics & numerical data*; D015203:Reproducibility of Results; D012650:Self Disclosure; D013183:Sputum; D011795:Surveys and Questionnaires; D001335:Vehicle Emissions
D001335:Vehicle Emissions