The large long-term study of US adults found that air pollution was significantly associated with an increased risk of hospital admissions for several neurological disorders – including Parkinson’s disease, Alzheimer’s disease, and other dementias.
Led by researchers at Harvard TH Chan School of Public Health, the study – published in The Lancet Planetary Health – looked at 17 years of hospital admission data from more than 63 million older US adults.
Our study builds on the small but emerging evidence base indicating that long-term PM2.5 exposures are linked to an increased risk of neurological health deterioration
This was then linked to the estimated fine particulate (PM2.5) pollution concentrations by zip code.
Researchers found that for every five micrograms per cubic metre of air (μg/m3) increase in annual PM2.5 concentrations, there was a 13% increased risk for first-time hospital admissions for Parkinson’s disease, Alzheimer’s disease and related dementias.
They said that the risk remained high even below the “supposedly safe” level of of 12 μg/m3 or less, according to the US Environmental Protection Agency.
Dr Stefan Reis, of the UK Centre for Ecology and Hydrology, said: “This study contributes to the growing body of evidence which suggests that exposure to air pollution even at comparatively low concentrations has widespread negative health effects.
“While respiratory and cardio-vascular diseases have been well known to be linked to air pollution, showing links between exposure to fine particulate matter and brain health in a comprehensive study highlights the importance to act swiftly in reducing exposure, not only in hotspot areas.”
“These findings are timely as they will inform the debate about adopting the World Health Organisation’s guideline value for PM2.5 of 10 μg m-3.
“However the study indicates that negative health impacts occur even below this level.
“Based on these and similar findings, reducing exposure to PM2.5 in the whole population should become a key priority for air pollution control policies.”
The study is the first nationwide analysis of the link between fine particulate pollution and neurodegenerative diseases in the US.
Women, white people, and urban populations were particularly susceptible, the study found.
The highest risk for first-time Parkinson’s disease hospital admissions was among older adults in the north-eastern US while for first-time Alzheimer’s disease and related dementias hospital admissions older adults in the Midwest faced the highest risk, it added.
Xiao Wu, co-lead author of the study, said: “Our study builds on the small but emerging evidence base indicating that long-term PM2.5 exposures are linked to an increased risk of neurological health deterioration, even at PM2.5 concentrations well below the current national standards.”