Air Pollution Increases Dementia & Lowers Fertility

Air Pollution Increases Dementia & Lowers Fertility


It was news in TSE (September 2 2018) that ushered in with a shocking bang that the air pollution in Imphal city, is twice the normal healthy limit, quoting L Radhakishore Singh, Chairman of Manipur Pollution Control Board. He said at a press conference: “Air quality of Imphal city is in [a] vulnerable stage as the level of air pollution at Keisampat junction has been found to be double the time (sic) above its permissible limit.”

In early 1950s, Imphal like New Delhi, was sparsely populated with very few automobiles on the road. Like Imphal, Delhi-air was dry but fresh except at the cram-full Chandni Chowk in Old Delhi, swarming with humanity and merchandising and with its Old Railway Station. The urbanisation of Imphal and Delhi, with increasing economic growth and easily available bank loans to buy motor vehicles, has increased air pollution. It will get worse unless the government find some solution to curb the menace.

In November 1917, when my wife and I came out of Delhi Airport, Delhi was a haze of smog (smoke and fog). Two days later, we travelled to Agra by car, wearing paper masks. It was smog all the way. We could see the November crop burning in the fields with plumes of smoke all along. Smog in Delhi from fog and the massive vehicular exhaust fumes from automobiles, especially diesel ones, was exacerbated by the smoke coming from burning crops in the neighbouring Haryana and the Punjab.

Data published by Central Government’s Pollution Control Board in Delhi, indicated that the pollution level in that season known as the Great smog of Delhi was “very unhealthy”. The pollution was far above the accepted normal. Levels of PM2.5 and PM10 (PM = particulate matter) went up to 999 mcg per cubic metre. The safe limit of these two are 60 mcg and 100 mcg respectively. 


According to the World Health Organisation, in developed and developing countries like India, air pollution caused by cars, factories and coal fires, is shortening lives. Globally, indoor and outdoor air pollution caused premature death for around 7 million in 2012.

In the UK, air pollution causes the equivalent of up to 36,000 early deaths every year. It’s linked to terrible health effects, including lung cancer and impaired lung development in children. The word ‘smog’ comes from the Great Smog of London that descended upon the normally foggy London City in December 1952. I was in college. The smog killed 12,000 people and took 64 years to solve. The smog was so thick that people had difficulty walking about. It was a strange fog, yellow and black in colour with a peculiar chemical smell. People just couldn’t breathe the thick opaque air and gasped. It was a death knell for the chronic bronchitic and asthmatic people, mostly elderly. After London’s 1952 killer smog, Britain put in some controls against air pollution. The result was the landmark 1956 Clean Air Act.     

By air pollution we understand that the air we breathe has an excess of harmful substances, such as gases, particulates (very small pieces of solids, mainly carbon, that are released into the air during incomplete combustion or burning (producing carbon monoxide, water and carbon particles), and biological molecules (fats, proteins, carbohydrates and nucleic acids). Incomplete combustion occurs from partial burning as it occurs with car engines, coal and natural gas burning. In a complete combustion eg cooking gas burning, carbon dioxide and water are released as in the case of photosynthesis by plants.


Diesel is a greater air polluter than petrol though it’s more efficient and emits less carbon monoxide. It produces more harmful gases (nitrous oxides) and particulate matter. Air pollution is said to occur when abundant harmful quantities of these substances are introduced into the Earth’s atmosphere from human activity and natural processes, such as volcanic eruptions.

Britain is still having ill effects on health from air pollution. As most people in the UK live in urban areas, exposure to traffic-related and other air pollutants is ubiquitous. Hence, even a relatively small increase in risk will result in a large public health impact.”

The above study was corroborated by the King’s College London research (September 2018), which found that pollution increases the risk of dementia. They found that Londoners who lived in the worst areas of the city for fine particles (known as PM2.5) were 20% more likely to develop dementia within seven years, while those who lived in the worst areas for nitrogen dioxide (NO2) were 40% more likely to develop it, even after accounting for age, class and other lifestyle factors.

One theory is that tiny particles and chemicals in polluted air absorbed into the body through the lungs cause damage or inflammation in the brain. The British study followed a Canadian study of 2.2 million people in 2017. That found those who lived next to a busy road were 12 % more likely to develop dementia.

In August 2018, a Chinese study on 20,000 people, suggested that air pollution leads to a decline in brain power, or cognitive function. Researchers, who tested people’s maths and verbal skills found their average scores decreased over three years of exposure to pollution.

Dementia is not the only illness that have been known to be produced by air pollution. It causes heart attacks and strokes. Breathing in polluted air over many years can cause arteries to become furred up inside, narrowing their lumen, known as atherosclerosis, which leads to heart attack and stroke in the long run. In the short term, it can trigger other heart problems. According to data from the Myocardial Ischemia National Adult project in UK, people are more likely to have a heart attack in the hours after having been exposed to a lot of traffic fumes.

Pollution can begin its effect on heart and circulatory system from an early age. Pollution can affect children in the womb. According to a paper published by the Royal London Hospital in 2018, soot particles were found inside the placentas of five women who gave birth to healthy babies. The tiny bits of carbon, typically created by burning fossil fuels, had been breathed in by pregnant mothers and travelled through their bodies into their placentas.

 Studies have suggested that children exposed to air pollution at an early age are more likely to develop asthma and lung infections, which can be fatal. Prof Jonathan Grigg of the Royal College of Paediatrics and Child health, says: “Air pollution can have major implications on the developing child’s health. Though pollution has not just been linked to causing asthma, it worsens the condition.”

At the height of summer when the heat can exacerbate pollutant chemicals circulating in the air from traffic fumes, people are more likely to suffer asthma attacks. Children are most at risk, according to a recent report by Global Action Plan on Clean Air Day. They found that primary and preschool children are exposed to 30% more pollution than adults simply because they are closure to the fumes from car exhausts [low height].

Though scientists do not know if the particles can reach the babies in the womb, they have evidence that pregnant women exposed to air pollution have problems, such as premature births, low birth weights, unexpected deaths of their babies and breathing problems in childhood. An American study in 2015, found that children whose mothers had been exposed to polycyclic aromatic hydrocarbons (PAHCs) that are present in in exhaust fumes, cigarette and coal smoke, were more likely to have behavioural problems, such as attention deficit hyperactivity disorder (ADHD).

Another worrying problem of air pollution is its effect on men fertility though it is not yet known exactly how pollution affects quality of sperms. In 2003, researchers in Internal Medicine, University of Naples in Italy, studied 85 men who were employed on motorway tollgates, who were constantly exposed to traffic fumes. They found the quality of their sperm was significantly lower than that of men who worked away from busy roads.

A study looked at many 15 to 49-year-old men in Taiwan, between 2001 and 2014. It assessed sperm quality and measured the level of fine particulate pollution in the air. It found that for every increase of particulate by 5 microgram per cubic metre, the number of normal sperm produced dropped by 1.29%. Another study in 2017 by the Chinese University of Hong Kong, looked at the sperms of 6,500 men. They found a strong association between PM2.5 exposure and abnormal sperm shape.     

It seems implausible that air pollution can have such an incredible effect on human health, but many studies have found evidence that it does. It’s more incredible that Imphal has joined the large polluted cities of the world. It thus needs a crackdown on air pollutants. Interestingly, Londoners with 2.56 million cars (twice the number of Meiteis in Manipur), can use the online Clean Air Route Finder (breathelondon.org/plan-lower-pollution-travel-routes), which maps out the cleanest routes between destinations using real-time air pollution measurements.

Website: drimsingh.com
Image Credit: pixabay.com

Dr IM Singh

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