Ambient Air Pollution, Health and Prescriptions in Northern Ireland
Research type
Research Study
Full title
Ambient Air Pollution, Health and Prescriptions in Northern Ireland
IRAS ID
274746
Contact name
Neil Rowland
Contact email
Sponsor organisation
Queen's University Belfast
Duration of Study in the UK
2 years, 0 months, 1 days
Research summary
Summary of Research
This study will investigate the individual-level association between outdoor air pollution exposure in Northern Ireland and health using data on receipt of medications as a measure of health. Air pollution is a known environmental risk factor for public health. Yet while much research has sought to understand the nature of its impact, there are many unresolved questions, particularly around its role in lesser studied illnesses such as dementia, Parkinson's and diabetes. This study will contribute to this health literature by linking Northern Ireland Longitudinal Study (NILS) data to Enhanced Prescriptions Database (EPD) data. The NILS is a large-scale, representative data-linkage study created by linking data from the Northern Ireland Health Card Registration system - for approximately 28% of the Northern Ireland population, or roughly 500,000 individuals - to the 1981, 1991, 2001 and 2011 Census returns and to administrative data from other sources. The EPD contains data on prescriptions issued by General Practices (GPs) in Northern Ireland. In this study, prescriptions for medicines used to treat the following conditions will be used: (1) the cardiovascular system; (2) the respiratory system (3) Parkinson's disease; (4) diabetes; (5) and dementia. Air pollution exposure, represented using modelled air pollution data created at a 1x1 km grid square resolution, will be assigned to each participant's anonymised household address contained in the NILS.
Summary of Results
This project aimed to investigate the relationship between outdoor air pollution exposure and health in Northern Ireland (NI). Health was measured as receipt of GP prescriptions issued to treat particular health conditions, including conditions relating to cardiovascular and respiratory systems, Parkinson’s disease, diabetes, and dementia. The project involved a statistical analysis of anonymised, individual-level data from the Northern Ireland Longitudinal Study (NILS) linked to prescriptions data from the Enhanced Prescribing Database (EPD). Since the study represented a secondary data analysis – in other words, the data were not collected by members of the research team and nor were they collected for research purposes – the study did not involve human participants.
The NILS is a large-scale data linkage project comprising an approximately 28% random sample of the NI population (a study cohort of 515, 930 individuals as of 2021) (Lowry et al., 2025). The NILS can be linked to health and social care administrative data via a Distinct Linkage Project. In this study, this was achieved through linkage with the EPD, held within the Business Services Organisation (BSO), which contains detailed information in relation to all primary care prescriptions dispensed in NI that are submitted to the BSO for payment. Specifically, the prescriptions data indicated whether, in each 6-month period (January-June, July-December) between 2011 and 2019, a NILS member received a prescription for one or more medications from a group of medications prescribed to treat each of the above conditions as classified using British National Formulary (BNF) codes. Air pollution exposure was measured using annual average 1x1km grid square modelled background concentration data published by the Department for Environment Food and Rural Affairs which was linked to NILS members’ (anonymised) residential address as recorded in both April and October from 2001 onwards. These data characterised the levels of residential outdoor air pollution over the course of each year.
Although there are a large number of epidemiological studies on the effects of air pollution on cardiovascular health, respiratory health and mortality, there are no such studies for NI, and relatively few elsewhere examining potential effects on other conditions such as Parkinson’s disease or dementia. This project contributed to the epidemiological literature on lesser-studied outcomes and provided the first empirical evidence using large-scale individual-level data for NI.
The project investigated several research questions: (i) effects of fine particulate matter and nitrogen dioxide exposure during childhood on breathing difficulties; (ii) effects of short- and medium-term fine particulate matter and nitrogen dioxide exposure on the onset of Parkinson’s disease among adults; (iii) effects of short- and medium-term fine particulate matter and nitrogen dioxide exposure on the onset of dementia among adults.
Data analysis was conducted by Office for National Statistics Accredited Researchers in a Trusted Research Environment at the Northern Ireland Statistics and Research Agency in Colby House, Belfast. Research outputs were presented at conferences, workshops and seminars as per the dissemination strategy set out from the outset of the study. Findings were also presented to the air pollution and health steering group, a group comprised of various stakeholder organisations which advised the research team during the life of the project.
In terms of outputs, a peer-reviewed journal article was published (Jahanshahi et al., 2025). This analysis found no statistical relationship between onset Parkinson’s disease and exposure to either fine particulate matter or nitrogen dioxide among adults (those aged 28 years or older in 2011) after accounting for other factors associated with onset, such as age and area-level deprivation, among other factors. There was suggestive evidence of a relationship among younger members of the study cohort, however, in which under 50s with higher exposure to fine particulate matter (and to a lesser extent, nitrogen dioxide) were at a higher risk of onset. The authors were cautious in their interpretation of this finding, and concluded that further research is required to understand whether it represents a true increase in risk or the effects of some other factor(s).
The research team is currently preparing papers on the effect of air pollution on onset dementia and on the effect of air pollution exposure during childhood on breathing difficulties. As these outputs emerge, the findings will continue to be disseminated to academic and non-academic audiences and will be submitted to relevant journals for consideration to be published. A new project using updated versions of the same data sources will examine other health outcomes.
Lowry et al., 2025: https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftrack.pstmrk.it%2F3ts%2Fdoi.org%252F10.1093%252Fije%252Fdyaf054%2FNBTI%2FI6TBAQ%2FAQ%2Fcb7d3003-d574-4fd6-93a2-1c9cf4501317%2F1%2FsjHjvKdx1S&data=05%7C02%7Capprovals%40hra.nhs.uk%7C9a79b028f8dd436ba61208de2d052764%7C8e1f0acad87d4f20939e36243d574267%7C0%7C0%7C638997697339886579%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=uppMCQqq4iINLRAcyWbRyd3L6qSJJjdgaJnySfuaFz0%3D&reserved=0
Jahanshahi et al., 2005: https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftrack.pstmrk.it%2F3ts%2Fdoi.org%252F10.1038%252Fs41531-025-01156-z%2FNBTI%2FI6TBAQ%2FAQ%2Fcb7d3003-d574-4fd6-93a2-1c9cf4501317%2F2%2F3HYP3-q9HH&data=05%7C02%7Capprovals%40hra.nhs.uk%7C9a79b028f8dd436ba61208de2d052764%7C8e1f0acad87d4f20939e36243d574267%7C0%7C0%7C638997697339914186%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=eV10GQfGZZ%2BGjPnw7pC7X4487kBPRN1%2BrxtTsYnYlXw%3D&reserved=0
Has the registry been updated to include summary results?: No
If yes - please enter the URL to summary results:
If no – why not?: N/A - the study was a secondary data analysis.Results from the strand of research on the risk of onset Parkinson's disease from air pollution were published in the peer-reviewed journal npj Parkinson's disease in October 2025. The paper is accessible here: https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftrack.pstmrk.it%2F3ts%2Fdoi.org%252F10.1038%252Fs41531-025-01156-z%2FNBTI%2FI6TBAQ%2FAQ%2Fcb7d3003-d574-4fd6-93a2-1c9cf4501317%2F2%2F3HYP3-q9HH&data=05%7C02%7Capprovals%40hra.nhs.uk%7C9a79b028f8dd436ba61208de2d052764%7C8e1f0acad87d4f20939e36243d574267%7C0%7C0%7C638997697339935368%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=4mdysgwVv8%2BcqwwwvuAj4kqy%2B2XB1AOMzP%2Bga9CQT7Q%3D&reserved=0
Future results are also expected to be published in environment or health journals.
Did you follow your dissemination plan submitted in the IRAS application form (Q A51)?: Yes
If yes, describe or provide URLs to disseminated materials: Dissemination has been partially completed and is ongoing.Results from the strand of research on the risk of onset Parkinson's disease from air pollution were published in the peer-reviewed journal npj Parkinson's disease in October 2025. The paper is accessible here: https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftrack.pstmrk.it%2F3ts%2Fdoi.org%252F10.1038%252Fs41531-025-01156-z%2FNBTI%2FI6TBAQ%2FAQ%2Fcb7d3003-d574-4fd6-93a2-1c9cf4501317%2F2%2F3HYP3-q9HH&data=05%7C02%7Capprovals%40hra.nhs.uk%7C9a79b028f8dd436ba61208de2d052764%7C8e1f0acad87d4f20939e36243d574267%7C0%7C0%7C638997697339955084%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=YLIJtX6JcxL8%2ByMY9k%2BWI5XN0cd0pwgSq1kolTi9tvU%3D&reserved=0
Future results are also expected to be published in environment or health journals.
REC name
HSC REC B
REC reference
20/NI/0050
Date of REC Opinion
24 Mar 2020
REC opinion
Favourable Opinion