Methods: We systematically searched 11 databases, three trial repositories and contacted an international panel of experts to identify published and unpublished experimental and epidemiological studies.
Results: 8,455 potentially relevant studies were identified; 852 papers were removed after de-duplication leaving 7,603 unique papers that were screened. Of these, 278 were reviewed in detail and 53 satisfied the inclusion criteria. Critical appraisal of the included studies indicated an overall lack of high quality evidence and substantial risk of bias in this body of knowledge. Aromatics (i.e. benzenes, toluenes, xylenes) and formaldehyde were the main VOC classes studied, both in relation to the development and exacerbations of asthma and allergy. Approximately equal numbers of studies reported that exposure increased risks or that exposure was not associated with any detrimental effects.
Conclusions: The available evidence implicating domestic VOC exposure in the risk of developing and/or exacerbating asthma and allergy is of poor quality and inconsistent. Prospective, preferably experimental studies, investigating the impact of reducing/eliminating exposure to VOC are now needed in order to generate a more definitive evidence-base to inform policy and clinical deliberations in relation to the management of the now substantial sections of the population who are at risk of either developing asthma/allergy or are living with established disease.