Researchers, at King’s College London, have estimated that 1 in 14 cases of dementia (potentially as many as 60,000 cases) may have been caused by exposure to nitrogen dioxides and smog, which are commonly emitted by diesel vehicles.
Currently, 850,000 people in the UK have dementia. This figure is predicted to rise to 1 million by 2025 and 2 million by 2050.
The scientific community recognises that genetics, obesity and smoking are risk factors of dementia. What is more, in previous editions of BC Disease News, we have discussed that a specific type of dementia, chronic traumatic encephalopathy (CTE), may be caused by the trauma of heading a football.
What of diesel exhaust fumes as a risk factor, however?
In a recent study, researchers investigated a cohort of 131,000 people, aged 50 to 79, living within Greater London. Air pollution data was compared against participant health records.
After a follow up period of 7 years, the researchers found that those who lived in areas polluted by the highest 20% of nitrogen dioxide emissions had a 40% higher risk of developing dementia. Further those who lived in areas polluted by the highest 20% of microscopic sooty particles had a 26% higher risk of developing dementia.
It has been suggested that microscopic particles in diesel fumes are inhaled and reach the lungs. From here, they can enter the blood stream. When contaminated blood reaches the brain, it is proposed that this provokes inflammation, a mechanism which may trigger dementia.
Aside from reaching the brain, microscopic particles were found in the wombs of pregnant women, which could imply the existence of additional, congenital health risks.
However, Dr James Pickett, Head of Research at the Alzheimer's Society, highlighted that this study does not show that pollution was the cause of the dementia:
'There is evidence that exposure to air pollution can cause small particles to enter the brain, but it's a huge leap to say that air pollution could lead to dementia and this study had several limitations’.
In edition 203 of BC Disease News (here), we reported that toxic diesel fume claims were on the rise. If the results of this study are genuine, then employees in the following professions would be most at risk.
Professions where exposure is most common include:
- Bridge and tunnel workers;
- Bus, lorry and taxi drivers;
- Car, lorry and bus service and repair workers,;
- Construction workers;
- Depot and warehouse workers;
- Heavy equipment operators;
- Loading dock and dockside ferry workers;
- Maritime workers;
- Material handling operators;
- Oil and gas workers;
- Railway workers;
- Refuse collection workers; and
- Tollbooth and traffic management workers.
 Ben Spencer, ‘Air pollution could be responsible for 60,000 cases of dementia in the UK, with people exposed to dirty air 40% more likely to develop the disease’ (18 September 2018 Daily Mail) <https://www.dailymail.co.uk/news/article-6182181/Air-pollution-responsible-60-000-cases-dementia-UK-people-exposed-to.html> accessed 25 September 2018.
 IOSH, DIESEL ENGINE EXHAUST FUMES: THE FACTS (September 2014 No Time To Lose) <http://www.iosh.co.uk/~/media/NTTL%20files/POL2531%20-%20Diesel%20Fact%20Sheet%20WEB.ashx> accessed 5 July 2017.
 SWORD is the Surveillance of work-related and occupational respiratory disease, a scheme which aims to determine the scale and patterns of work-related respiratory disease in the UK. 418 respiratory physicians participate in reporting occupational respiratory disease. In 2002, SWORD plus several other schemes were relaunched as THOR, The Health and Occupational Asthma in Great Britain 2014, HSE.
 Henneberger PK, Redlich CA, Callahan DB et al. An official American Thoracic Society Statement: Work Exacerbated Asthma. Am J Respir Crit Care Med. 2011; 184:368-378.
 Nicholson et al. 2005
 HSE, ‘Work aggravated asthma: A review of reviews’; Lisa Bradshaw and David Fishwick, Health and safety Laboratory
2014; RR1005 Research Report
 Nicholson et al. 2005
 HSE, ‘Work aggravated asthma: A review of reviews’; Lisa Bradshaw and David Fishwick, Health and safety Laboratory 2014; RR1005 Research Report