Objectives: Childhood asthma is a complex condition where many environmental factors are implicated in causation. The aim of this study was to complete a systematic review of the literature describing associations between environmental exposures and the development of asthma in young children.

ObjectiveTo complete a systematic review of the literature describing associations between all environmental exposures and asthma symptoms and exacerbations in children up to mean age of 9 years.DesignSystematic review.SettingReference lists of identified studies and reviews were searched for all articles published until November 2013 in electronic databases (MEDLINE, EMBASE, CINAHL, Cochrane Controls Trials Register).ParticipantsStudies were selected which examined a link between exposure to environmental factors and asthma symptoms and exacerbations where the study participants were children with a mean age of ⩽9 years.Primary and secondary outcome measuresIndices of asthma symptoms, control and exacerbations.ResultsA total of 27 studies were identified including eight where inhaled allergens and four where environmental tobacco smoke (ETS) were the exposures of interest. There was evidence that exposure to allergen, ETS, poor air quality and unflued heaters had a modest magnitude of effect (ORs between 2 and 3). There was also evidence of interactions observed between exposures such as allergen and ETS.ConclusionsExposure to inhaled allergens, ETS, unflued heaters and poor air quality has an important effect on exacerbations in young children with asthma and should be minimised or, ideally, avoided. Better understanding of the effect of exposure to damp housing, air conditioning and dietary factors plus interactions between environmental exposures associated with exacerbations is required.

A systematic review was performed to identify any associations between pesticide exposure and the occurrence (both prevalence and incidence) of airways disease (asthma and chronic obstructive pulmonary disease) and wheezing symptoms.PubMed, MEDLINE, Embase, Scopus, CINAHL, Google Scholar and the Cochrane Database of Systematic Reviews were searched between September 2010 and October 2010 for papers with the inclusion criteria of English language, published after 1990, peer-reviewed and nondietary exposure. From a total of 4390 papers identified, 42 were included after initial assessment of content. After evaluating the included studies for quality, those considered to be at high risk of bias were excluded, leaving a total of 23 relevant papers.Results suggest that exposure to pesticides may be associated with prevalent asthma, but methodological issues, such as cross-sectional/case-control design, measurements of exposure and limited adjustment for confounders, limit the strength of the evidence base in this area. The association between pesticide exposure and asthma appears to be more evident and consistent in children than in adults. Exposure to pesticides may be associated with COPD; however, the strength of evidence for an association with COPD is weaker than for asthma. As the exposure metrics within each health end-point varied across studies, no metaanalyses were carried out. @ERSpublications Pesticide exposure may be associated with increased respiratory symptoms; evidence is lacking on specific pesticides http://ow/ly/U5Qr7