Air pollution is an established threat that, based on World Health Organisation (WHO) data, causes about seven million deaths a year.

Poor air quality can increase the risk of stroke, heart disease, lung cancer, and respiratory diseases — both chronic and acute.

A new study shows a direct link between air pollution — even at 'safe' levels — and a higher risk of diabetes.



It's estimated that over 420 million people worldwide currently have diabetes, with WHO data predicting that, by 2030, diabetes will be the seventh leading cause of death worldwide.

There are many possible triggers for the disease, among which are a sedentary lifestyle, an unhealthy diet, as well as obesity — but it has now been shown that external agents like air quality are closely related to the development of diabetes, with analysis suggesting pollution negatively impacts the body's insulin production levels.

Researchers estimate that pollution contributed to 3.2 million new cases of diabetes worldwide in 2016, about 14% of all new cases that year. They established this using the PM 2.5 index, which measures air quality from suspended particles with a diameter of less than 2.5µm in the atmosphere.

A diabetes patient filling a syringe of insulin for injection. AP Photo/Reed Saxon

Published June 29 in The Lancet Planetary Health, the study was conducted by researchers at the University of Washington School of Medicine in collaboration with scientists from the VA St. Louis Health Care System's Center for Clinical Epidemiology.

1.7 million US veterans with no history of diabetes were followed over a median of 8.5 years, after which the data obtained was linked to EPA's ground-based air monitoring systems and space satellites operated by the National Aeronautics and Space Administration (NASA). To assess outdoor air pollution levels, researchers analysed microscopic particles of airborne dust, dirt, smoke, soot, and liquid droplets.

Using all the data they'd collated, they designed a model capable of assessing the risk of diabetes with different levels of pollution.

The data indicates a higher risk of diabetes in poorer countries

According to the results, when a section of participants were exposed to pollution at about 5-10 micrograms per cubic meter of air, about 21% of them developed diabetes. When that exposure increased from 11.9-13.6 micrograms per cubic meter of air, that statistic rose to 24%.

Therefore, one of the findings was that the risk of developing diabetes based on air quality increased in lower-income countries simply because they lacked clean air policies and systems to minimise the impact of air pollution on society. Disability-adjusted life year (DALY or DALY) rates increased as the World Bank's income classification and socio-demographic index declined.

The disability-adjusted life year is a measure of the burden of global disease, which is applied when estimating overall health and life expectancy in countries. The results estimated that 8.2 million healthy life years were lost in 2016 due to pollution-related diabetes.

Map A shows the age-standardised incidental diabetes 'burden' attributable to PM2.5 per 100,000 population, while Map B reflects the age-standardised 'disability adjusted life year' due to incidental diabetes that's attributable to PM2.5 per 100,000 population. The Lancet Planetary Health

It follows that poverty-stricken countries with higher pollution levels, such as Afghanistan, Papua New Guinea and Guyana, face a higher risk of diabetes while more developed countries see a lower risk.

The study also found that in 2016 there were 206,105 deaths across the world from diabetes that were attributable to PM2.5 exposure, demonstrating that these small particles are very harmful to health. The introduction of controlled PM 2.5 as pollutants wasn't brought into European legislation until 2010.