‘Safe’ pollution levels could cause dementia or Parkinson’s disease
LIVING in a polluted area significantly raises the risk of dementia, according to the world’s largest study on the issue.
Scientists found that people are increasingly likely to be hospitalised with Alzheimer’s or Parkinson’s disease, the higher the levels of toxic air in their postcode.
The research showed any air pollution – even within ‘safe’ limits – is linked to neurological diseases.
The study by Harvard University, published in the Lancet Planetary Health journal, drew on data from 63 million adults. It is the strongest evidence that dirty urban air can damage the brain.
Air pollution is already known to cause lung disease, asthma and heart disease, some of the country’s worst killer diseases.
Yesterday’s study analysed the link between progressive neurological conditions and tiny pollution particles known as PM2.5, which form as a result of burning diesel, petrol, wood and coal.
The World Health Organization states that the amount of PM2.5 pollution must not exceed annual average levels of 10 micrograms of toxic particle per cubic metre of air.
Experts compared the health records of 63 million over-65s in America with air pollution data for their postcode.
The participants were followed over 17 years, during which time one million developed Parkinson’s disease and 3.4 million dementia.
For every five microgram rise in air pollution, the likelihood of being hospitalised with either Alzheimer’s or Parkinson’s rose by 13%. Women were slightly more vulnerable than men.
The study found that this increased risk existed even when air pollution was relatively low, showing there is ‘no safe threshold for harmful pollution’. It concluded: ‘Long-term exposure to air pollution is significantly associated with a higher risk of neurological health deterioration, even at concentrations less than the current national standards.’
The microscopic pollution particles are less than 1/30th the width of a human hair, and are able to penetrate the lungs and enter the bloodstream.
The authors said they may cross the blood-brain barrier, increasing inflammation in the brain and causing conditions including dementia.
Two years ago researchers at King’s College London calculated that air pollution could account for around 7% of dementia cases.
According to the HSE’s website: ‘Air quality is important because air contaminants can affect health in humans.
‘Contaminants that affect people in Ireland include gases that may accumulate indoors, such as radon, carbon monoxide and particulate matter from open fires.
‘Outdoor pollution may arise from fuel emissions, for example from road traffic or from smoky coal use.’
Fiona Carragher, director of research and influencing at Alzheimer’s Society, said: ‘Air pollution is a hot topic in dementia research. While this study adds to the evidence that air pollution could raise your dementia risk, we still need to know how particulate pollution might be causing changes in the brain, and if these lead to dementias.
‘This study only looked at people with dementia admitted to hospital and we can’t rule out the possibility of other factors.’
Around 12,000 people in Ireland live with Parkinson’s, a progressive neurological condition.
Mike Childs, of Friends of the Earth, said so many cities and towns ‘fail the WHO standard for particle matter – the most dangerous type of air pollution’.
‘Checked toxic air in postcodes’