The peer-reviewed research, led by scientists in Queen’s University Belfast’s Cancer Epidemiology Research Group in the Centre for Public Health is the first nationally representative study to estimate the number of lung cancers attributable to air pollution in Northern Ireland. 

Working with an international team including experts from the International Agency for Research on Cancer (IARC-WHO) – the global authority on cancer prevention – the researchers estimate that around 10% of lung cancer cases in Northern Ireland are due to exposure to fine particulate matter (PM2.5). This amounts to 137 cases each year. 

The team linked the postcodes of more than 900 lung cancer patients and over 8,000 cancer-free controls to high-resolution historical air pollution maps.  

This innovative approach allowed them to estimate long-term exposure to PM2.5 – tiny particles that penetrate deep into the lungs – and calculate the associated cancer risk. 

The study estimates that: 

• People in the most polluted areas have a 37% higher risk of lung cancer than those in the least polluted areas. 

• The excess risk is especially marked in women, who show a 79% higher risk at the highest exposure levels compared to women in the lowest. 

• On a population scale, exposure above the WHO’s former guideline of 10 µg/m³ - still regularly exceeded in many areas - accounts for 10% of lung cancers in Northern Ireland. 

Lung cancer is the leading cause of cancer death in Northern Ireland, with over 1,300 new diagnoses every year. While smoking remains the largest risk factor, this study underscores that air pollution is an urgent and preventable cause of the disease, which should be tackled in addition to continued action to reduce smoking. 

Belfast is among the most car-dependent cities in Europe, with vehicle emissions a major source of harmful particulate pollution. In addition, a significant share of Northern Ireland households relies on home heating oil, with coal and other solid fuel use also widespread in rural areas.  

Tackling these major sources of combustion, by speeding up investment in renewable energy, reliable and affordable low-carbon public transport, and alternative heat sources in rural areas, would further reduce cancer risk and deliver important climate benefits. 

Mrs Rawan Alhattab, lead author and PhD Student from the Centre for Public Health at Queen’s University Belfast says: “These findings remind us that air pollution is not just an environmental issue—it is a clear and preventable threat to public health. Every lung cancer case linked to air pollution represents suffering that could have been avoided if we act decisively to reduce exposure.” 

Dr Dan Middleton, senior author of the study and Lecturer and Cancer Epidemiologist from the Centre for Public Health adds: “Outdoor air pollution has been classified as a Group 1 human carcinogen since 2013, so these findings come as no surprise. They should, however, come as a wake-up call to policy makers, whose inadequate efforts to tackle air pollution are costing lives – a toll we are now able to quantify.” 

The authors emphasise that far more urgent measures are needed to reduce exposure. Although this analysis focused solely on lung cancer, the team is now exploring whether air pollution contributes to other cancer types. 

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Media inquiries to Sian Devlin at s.devlin@qub.ac.uk