Impact of indoor air pollution in nursery and primary schools on childhood asthma.

Poor indoor air quality in scholar environments have been frequently reported, but its impact on respiratory health in schoolchildren has not been sufficiently explored. Thus, this study aimed to evaluate the associations between children's exposure to indoor air pollution (IAP) in nursery and primary schools and childhood asthma. Multivariate models (independent and multipollutant) quantified the associations of children's exposure with asthma-related health outcomes: reported active wheezing, reported and diagnosed asthma, and lung function (reduced FEV1/FVC and reduced FEV1). A microenvironmental modelling approach estimated individual inhaled exposure to major indoor air pollutants (CO2, CO, formaldehyde, NO2, O3, TVOC, PM2.5 and PM10) in nursery and primary schools from both urban and rural sites in northern Portugal. Questionnaires and medical tests (spirometry pre- and post-bronchodilator) were used to obtain information on health outcomes and to diagnose asthma following the newest international clinical guidelines. After testing children for aeroallergen sensitisation, multinomial models estimated the effect of exposure to particulate matter on asthma in sensitised individuals. The study population were 1530 children attending nursery and primary schools, respectively 648 pre-schoolers (3-5 years old) and 882 primary school children (6-10 years old). This study found no evidence of a significant association between IAP in nursery and primary schools and the prevalence of childhood asthma. However, reported active wheezing was associated with higher NO2, and reduced FEV1 was associated with higher O3 and PM2.5, despite NO2 and O3 in schools were always below the 200 µg m-3 threshold from WHO and National legislation, respectively. Moreover, sensitised children to common aeroallergens were more likely to have asthma during childhood when exposed to particulate matter in schools. These findings support the urgent need for mitigation measures to reduce IAP in schools, reducing its burden to children's health.

Indoor air pollution on nurseries and primary schools: impact on childhood asthma--study protocol.

BACKGROUND: Several studies have demonstrated an association between the exposure to indoor air pollution (IAP) and childhood asthma. Evidence is suggesting that several air pollutants may contribute to both exacerbation and development of asthma, but some uncertainty remains concerning the specific causative role of IAP. This paper reports an epidemiologic study aiming to reduce the existing lacks on the association between long-term exposure to pollution mixtures and the development and exacerbation of childhood asthma. METHODS/DESIGN: Based on the implementation of the study in 8 nurseries and 8 primary schools, from which, 2 nurseries and 2 primary schools in sites influenced by traffic and other 2 nurseries and 2 primary schools in background sites at urban and rural areas, the study will analyse the exposure to both urban and rural pollution as well as to traffic emissions (some homes of the children will be included in the study). Furthermore, based on the answers to validated questionnaires (as those used in the International Study of Asthma and Allergies in Childhood - ISAAC) filled in by the parents and on medical exams, the study will assess the prevalence, incidence and exacerbation of asthma, thus considering both short and long-term effects. The approximate number of children in the study will never be less than 600, guaranteeing 80% of study power (significant at a 5% level). DISCUSSION: This study intends to contribute for the understanding of the role of environmental factors, namely indoor air pollution, on asthma considering a risk group of different ages, and for the development of preventive measures, which are considered priority issues by the European Commission, according to the European Environmental Agency and the World Health Organization.