In March 2019 researchers from France published their review to assess environmental factors which may be involved in the development of asthma. The number of individuals suffering from asthma has increased rapidly since the early 1970s, and it is thought that only changes in exposure to environmental factors, together with changes in lifestyle, are likely to explain such a rapid increase. Exposure to allergens is a risk factor for allergic sensitisation, and allergic sensitisation is a risk factor for allergic asthma. It is recognised that exposure to air pollution and maternal smoking, whilst in the womb and post-natally, increase the risk of asthma in children. However, in adults, there is little information and results remain controversial with regard to these types of exposure and asthma incidence. In addition, further research is required to assess the effect of exposure to phenols, phthalates and perfluorinated compounds, which are widespread in the environment and may be associated with asthma, especially in children. Frequent use of chemicals for home cleaning, especially in the form of sprays, is a known risk factor for the development of adult asthma and it is thought that the use of cleaning products in the home might also be a risk factor for asthma in children. However, the chemicals that may be responsible are still to be identified. Occupational asthma is a major sub-type of adult asthma and it is thought that this could be significantly due to occupational exposure to cleaning products. Whilst there is evidence that diet during pregnancy or during childhood may be associated with the risk of asthma in children, there is currently insufficient evidence that diet may be associated with an increased risk in adults. Further research is required to clarify whether there is any association between nutritional factors and asthma development and also to decipher the role of all the environmental factors which may also be involved.
Leynaert B et al. Environmental risk factors for asthma development. Presse Med. 2019 Mar;48(3 Pt 1):262-273.