From dementia to altering brain structure in kids, from sudden heart attacks to autism risk -- the health impact of long-term exposure to air pollution is not just respiratory illnesses, as several new studies have documented this year alone.
These new investigations raise a fresh alarm for the governments and agencies in India to fast-track their efforts to safeguard the population from air pollution.
Exposure to above-average levels of outdoor air pollution increases the risk of death by 20 per cent, and the risk of death from cardiovascular disease by 17 per cent, according to a team of researchers, including one of Indian origin.
The study, published in the journal 'PLOS ONE' in June, showed that using wood or kerosene-burning stoves, not properly ventilated through a chimney, to cook food or heat the home also increases the overall risk of death (by 23 per cent and 9 per cent, respectively) and cardiovascular death risk (by 36 per cent and 19 per cent, respectively).
"Our study highlights the role that key environmental factors of indoor/outdoor air pollution, access to modern health services, and proximity to noisy, polluted roadways play in all causes of death, and deaths from cardiovascular disease in particular," said researcher Rajesh Vedanthan from NYU Langone Health.
In a first-of-its-kind study, published in the peer-reviewed journal 'Environmental Pollution' in September, researchers linked exposure to air pollutants like particulate matter PM2.5 -- particularly in the first five years of life starting from the womb -- and alterations in the brain structure that may put children at psychiatric and cognitive disorder risks later in life.
The study, led by the Barcelona Institute for Global Health (ISGlobal), found an association in children aged 9-12, between exposure to air pollutants in the womb and during the first 8.5 years of life and alterations in white matter structural connectivity in the brain.
Abnormal white matter microstructure has been associated with psychiatric disorders (depressive symptoms, anxiety and autism spectrum disorders).
In April, China-based researchers claimed that exposure to air pollutants -- even at levels below World Health Organization (WHO) air quality guidelines -- may trigger a heart attack within an hour.
The study, published in the American Heart Association's journal 'Circulation', found exposure to any level of four common air pollutants -- fine particulate matter, nitrogen dioxide, sulphur dioxide and carbon monoxide -- could quickly trigger the onset of acute coronary syndrome (ACS).
ACS is an umbrella term describing any situation in which blood supplied to the heart muscle is blocked, such as in a heart attack or unstable angina, chest pain caused by blood clots that temporarily block an artery.
"The adverse cardiovascular effects of air pollution have been well documented. But we were still surprised at the very prompt effects," said Haidong Kan, professor in the School of Public Health at Fudan University in Shanghai.
"Another surprise was the non-threshold effects of air pollution. Any concentration of air pollutants may have the potential to trigger the onset of a heart attack," Kan added.
According to UK-based researchers, air pollution is likely to increase the risk of developing dementia.
The Committee on the Medical Effects of Air Pollutants in the UK published its findings in July this year, after reviewing almost 70 studies that analysed how exposure to emissions affect the brain over time.
The 291-page report concluded that air pollution is likely to increase the risk of accelerated "cognitive decline" and of "developing dementia" in elderly people.
Experts believe this is due to the impact of pollutants entering the circulatory system, affecting blood flow to the brain.
Last month, another study found that the impact of breathing diesel exhaust fumes may be more severe for women than men.
Hemshekhar Mahadevappa and Neeloffer Mookherjee from the University of Manitoba in Winnipeg, Canada, looked for changes in people's blood brought about by exposure to diesel exhaust.
In both females and males, they found changes in components of the blood related to inflammation, infection and cardiovascular disease, but they found more changes in females than males.
"These are preliminary findings, however, they show that exposure to diesel exhaust has different effects in female bodies compared to male and that could indicate that air pollution is more dangerous for females than males," said Mookherjee.
This is important as respiratory diseases such as asthma are known to affect females and males differently, with females more likely to suffer severe asthma that does not respond to treatments.