A new study has shown ageing in the brain may be caused by air pollution.
The research team from University of Southern California has presented its findings at the Gerontological Society of America's annual scientific meeting.
Postgraduate doctoral fellow Jennifer Ailshire carried out research using data from the American Environmental Protection Agency and the Health and Retirement Study and found older adults performed worse on thinking tests if they lived in areas with high levels of air pollution.
She said: "As a result of age-related declines in health and functioning, older adults are particularly vulnerable to the hazards of exposure to unhealthy air."
Ms Ailshire added air pollution has been linked to increased cardiovascular and respiratory problems in previous studies.
Research recently conducted by the University of Athens in Greece found breathing is impaired by secondhand smoke within only 20 minutes, with Dr Panagiotis Behrakis from the university noting even a small amount of exposure can damage airways.
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