Two-thirds of the death burden occurs in developing Asia, including India
Photo: iStock (The story was first published in Down To Earth's publication Body Burden: State of India's Health, 2015)
Uncontrolled emission of air pollutants means increasing burden of air pollution-related illnesses and premature deaths. Death toll due to outdoor air pollution-related illnesses alone has increased worldwide by a whopping 300 per cent in the last decade: from 800,000 in 2000 to 3.2 million in 2012.
Two-thirds of the death burden occurs in developing Asia, including India. The GBD report estimates that in 2010, some 52 million years of healthy life were lost and more than 2.1 million people died at early ages due to fine particles of air pollution in Asia; this is two-thirds of the burden worldwide. Killer outdoor air contributes to 1.2 million deaths in East Asia which is in throes of high level of economic growth and motorisation and 712,000 deaths in South Asia (including India) which is at the take-off stage. This is much higher than the combined death toll of 400,000 due to air pollution-related illnesses in the 27 EU countries, Eastern Europe and Russia.
In Delhi, which was named as the most polluted city in the world by WHO in 2014, air pollution is responsible for 10,000 to 30,000 annual deaths, according to a study published in Environmental Science and Technology on June 16, 2015. This means the capital city loses 80 lives every day due to pollution from PM2.5 (see ‘Why Delhi fails in its fight against pollution’ on facing page).
WHO estimates that some 80 per cent of outdoor air pollution-related premature deaths worldwide are due to ischaemic heart disease and strokes, while 14 per cent deaths are due to chronic obstructive pulmonary disease or acute lower respiratory infections; and 6 per cent due to lung cancer. Doctors in India who deal with new health risks from worsening air quality say the situation is no better in the country. According to the Delhi Cancer Registry at AIIMS, the capital reports 13,000 new cases of cancer every year. About 10 per cent of them suffer from lung cancer. “We have seen that 90 per cent of lung cancer patients have a history of smoking. But recently after analysing the data of 600 patients, I found that 30 per cent of them did not have any history of smoking,” says Vinod Raina, head of the medical oncology department at Dr B R Ambedkar Institute Rotary Cancer Hospital, AIIMS, Delhi.
“The number of people with respiratory problems has increased by 10-15 per cent in the past decade. Adolescents who had never wheezed as children are wheezing now. Children born healthy are coming back to us in four to six weeks with wheezing,” said Sanjeev Bagai, chief medical director of Nephron Clinic and Health Care in Delhi.
Medical practitioners and scientists are also beginning to find links between air pollution and illnesses ranging from Alzheimer’s disease and diabetes to debilitating eye disorders. There have been growing incidences of premature deliveries and children with chromosomal and genetic disorders.
Illnesses like allergic rhinitis, chronic running nose, chronic allergic conjunctivitis, ear infections, sore throats and pneumonia are also on the rise, says Bagai. All these are because of environmental pollution, he adds.
A new study by the University of Montana in the US, along with other research institutions, has found that air pollution impacts levels of metabolites responsible for cognitive functions in young
people who are carriers of the Alzheimer’s gene. A decrease in the ratio of hippocampal metabolites significantly affects children and their parents with the APOE e4 (allele 4 of apolipoprotein E) gene.
These findings, based on results in young people living in Mexico City, were published in the Journal of Alzheimer’s Disease on September 24, 2015. Carriers of APOE e4 face a higher risk of developing Alzheimer’s disease, and are also susceptible to poor outcomes in traumatic brain injury recovery.
Mexico City is highly urbanised and the city's environmental pollution affects millions of children who are exposed to PM2.5 every day. The study focused on children and one of their two parents who shared the gene. It found that the ratio of metabolites has severely decreased in Alzheimer’s gene-carrying children in Mexico City than in those living in low-polluting cities. A fall in this ratio may result in early neurodegeneration in young urbanites.
Some 80 per cent of outdoor air pollution-related premature deaths worldwide are due to ischamic heart disease and strokes, 14 per cent deaths due to chronic obstructive pulmonary disease or acute lower respiratory infections, and six per cent due to lung cancer. Outdoor air pollution is also responsible for rising cases of Alzheimer’s disease.
Another population-based cohort study done in Taiwan has found that the risk of Alzheimer’s disease increased by 138 per cent with every 4.34 μg/cum increase in PM2.5 level in the ambient air.
Published in the Journal of Alzheimer’s Disease, the study investigated the association between long-term exposure to ozone and PM2.5 and Alzheimer’s disease in 95,690 individuals aged 65 or above between 2000 and 2010.
Neurologists and cardiologists from the University of Edinburgh, in the UK, recently reviewed scientific studies conducted across 28 countries between 1990 and 2014, and found a definitive
connection between air pollution and stroke-related deaths and illnesses that require hospitalisation.
The scientists found that both PM2.5 and PM10 may increase the risk of a stroke. Chances of stroke further increase when a person is exposed to higher level of PM2.5. The review, known as meta-analysis in scientific lexicon, was published in British Medical Journal in March 2015.
The scientists also found a definite link between the risk of stroke and gaseous pollutants, such as CO, sulphur dioxide (SO2) and the most common, nitrogen dioxide (NO2). “All these pollutants are
emitted directly from diesel vehicles,” says Anoop Shah, lead researcher of the meta-analysis. Exposure to NO2 can cause haemorrhagic stroke, which occurs when a blood vessel ruptures and bleeds into the brain. All gaseous pollutants, except ozone, can cause ischemic strokes, where thickness of blood increases to the extent that it causes clots and obstructs blood supply to the brain. Shah says chances of strokes are higher on the day of exposure to high air pollution and among those who live in areas with high air pollution.
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