Air pollution, pollen, asthma and hayfever and their interactive effect on cognitive development: environment & health data linkage feasibility study

Asthma exacerbations are one, or a combination of; shortness of breath, coughing, wheezing and chest tightness. High levels of air pollution and pollen (aeroallergens) are each thought to be associated with instances of asthma exacerbations and hayfever. In combination, some types of air pollution and pollen are thought to increase the likelihood of asthma exacerbations.

Research into child cognitive development has been limited previously to small-scale studies through the necessity of recruiting participants to complete detailed tests. There have been studies investigating if children with asthma and hayfever perform less well in their examinations compared to children without asthma or hayfever. Previous studies have found differing results; one study found that attainment increased slightly for children with asthma, but researchers did not use the child's exposure to air pollution or pollen. Further research is needed to fully explore the influence of air pollution and pollen on educational attainment for children with and without asthma and hayfever.

In our study we will bring together air pollution, health and education data for each child using data linkage methods, and routinely collected environment, health and education data. The SAIL databank, containing routine data for large numbers of children, is able to use educational attainment for each child as a substitute for cognitive development. Our study will include all 22,000 children resident in a city, for different groups of children who took exams in several successive years (2003 - 2012). Our study will include spatial differences in air pollution, introducing differences between children within the asthma and non-asthma groups. This will allow us to directly evidence the impact of air pollution on the pathway to educational attainment. For the first time we will use pollution levels at both the child's home and school using novel data linkage methods. We will use data about their home type and age that may change the amount of air pollution the child breathes, acknowledging that children spend time indoors. We will also data link to other members of their household to investigate if they live with smokers.

We will use data about the individual child, for example, if each is eligible for free school meals. This will help to take into account if the child comes from a home that earns a low wage, so removing the possibility that our study will simply find known differences due to deprivation. We will also include the child's week of birth and gender. The statistical methods we use will allow us to study children from many different schools even though there are systematic differences between schools resulting in different outcomes. Including as much information that we have using characteristics about the school, such as deprivation, gender mix and overall attendance levels, will let us know how much each of these factors affects our educational outcome.

Our current feasibility study will use home and school air pollution levels to include changes for children living in different streets; we will restrict our analyses to use air pollution and pollen summaries for the critical pre-examination period only. That is, we will analyse only the short-term effect of air pollution and pollen on educational attainment. We will evaluate if increased air pollution and pollen in the critical pre-exam period is associated with changes in exam results in susceptible individuals.

During a workshop towards the end of this feasibility study, the team and stakeholders will assess the data needed to create a dataset to analyse the long-term effects of exposure to different levels of air pollution and pollen, beginning with mother-child pairs and the mother's educational attainment, including with the environment to which the mother is exposed during pregnancy.

Keywords: Air pollution, pollen and asthma, hayfever, educational attainment

Knowledge of a wider variety of impacts of air pollution will add to the evidence base informing policy. Associations between air pollution and educational attainment, and interactions with high pollen counts during the critical exam period for pupils with asthma and hayfever, will be evidenced in this feasibility study.

The UK population are key stakeholders who would directly benefit from any positive change (e.g. in air quality regulation) influenced by our findings, and from a greater awareness of the links between atmospheric pollutant exposure, health, and cognitive development. We recently presented evidence on how an air pollution alert system increased emergency admissions to hospital. All stakeholders at the Welsh Air Quality Forum (Welsh Government, Local Authorities, Public Health Wales) agreed it is necessary to reduce pollution rather than expecting people to change behaviour.

National and local policy makers, such as the local NHS boards tasked with addressing health inequalities, will benefit from firmer evidence on how environmental exposure impacts educational attainment. The wider public will benefit from regulators' and policy makers' enhanced knowledge of the likely effectiveness of air quality policies for improving health and educational attainment. The public will also directly benefit from increased understanding of the risks associated with exposure to pollutants, delivered during a follow-on project. Specifically those who may receive the greatest benefit are those vulnerable to air pollution and aeroallergens, including school children sitting their final examinations.

Other UK policy makers and regulatory agencies are key stakeholders; UK Department for Environment, Food and Rural Affairs (DEFRA), Communities and Local Government (CLG), UK Department for Education (DfE), the UK Department of Health (DH), Health Protection Agency (HPA), Environment Agency (EA), Scottish Environment Protection Agency (SEPA) and Welsh Government. They will benefit from improved knowledge of spatial heterogeneity in air pollution and associated health effects as well as new findings on the health effects of multiple environmental exposures and their interactions. Stakeholders will be invited to our final workshop, to discuss feasibility project results, illustrating the main findings of our analysis as an outcome of the project. They will also be involved in further discussions on the development of a research project to analyse the long-term impacts of air pollution and pollen on cognitive development.

The findings will also be of use to advocacy agencies concerned with health inequalities, e.g. WHO, and Joseph Rowntree Foundation (JRF), as well as government agencies and local authorities around the UK such as the NHS, HPA. The Met Office will benefit from the evidence into the health impacts associated with air quality policies. The JRF will benefit from having clearer insights into the factors that affect the health of the most disadvantaged groups and hence provide clearer policy guidance. National and local policy makers such as the local NHS boards tasked with addressing health inequalities will benefit from firmer evidence on which to base their decision-making.

The academic beneficiaries of this project span the environmental (including built environment), public health, and social science disciplines interested in the health impacts of both single and mixtures of atmospheric pollutants and their interactions with aeroallergens at crucial stages in their educational development. Data will be available through SAIL (saildatabank.com) for all academics internationally to analyse pending approval by an independent Information Governance Review Panel. We will circulate project results through the Farr Institute and the Administrative Data Research Network.