How Pollution Affects Kids: Development Delay, Stunted Growth

This week in the Breathe series, Kiran Manral writes on how air pollution may lead to low birth weight and developmental delay among children.

Kiran Manral
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If you thought that the primary effect of the pollution your children are exposed to only causes them to fall ill, with respiratory ailments, you couldn’t be further from the truth. Apart from respiratory ailments, autoimmune diseases, affecting moods, and more, perhaps the scariest manifestation is how extreme pollution can stunt growth and affect the brain development of children.


An interesting study done by researchers at IIT Delhi found that the highest decline in height amongst children is of those born between November and January, the months when the pollution levels peak. The researchers surveyed over 200,000 children between February 2010 to December 2015 to arrive at this conclusion.

The research published in the journal, Environmental Health, concluded that newborn babies as well as fetuses of women in their third trimester are more likely to be shorter for their age, or be stunted later in life if the mother had been exposed to high levels of air pollution during pregnancy.

Says Dr. Megha Consul, Principal Consultant, Pediatrics, Max Gurgaon, “A child’s future is pinned on the first 1000 days of development when brain growth is most rapid. Any damage during this critical period can cause long-lasting effects on their health and well-being. Early childhood is also a critical period for the continued development and maturation of several biological systems such as the brain, lung, and immune system and air toxins can impair lung function and neurodevelopment, or exacerbate existing conditions, such as asthma. Infants who were born premature or growth-retarded may be particularly vulnerable to additional environmental insults, for example, due to the immaturity of the lungs at birth.”

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Air pollution in pregnant mothers can affect the growth of child in-utero and lead to intrauterine growth retardation and stunting. In countries like India where air pollution is higher, it leads to repeated respiratory tract infections with multilevel affections of lungs and decreases the immunity of these children which in turn affects growth and leads to stunting and malnourishment. Also, household air pollution is common in villages and lower socioeconomic people where children are at home a majority of the time and get affected with household smoke. Stunting also affects brain development in some of them.” Dr. Zinal Unadkat Shah, pediatrician and lactation consultant.

According to the research, an increase of 100 μ g/m3 in the ambient PM2.5 levels during the birth month was had a direct correlation with a decrease of 0.05 in the height-for-age chart amongst children whose mothers were exposed to pollution. To arrive at these conclusions, the researchers analyzed population data from the Demographic and Health Survey 2015-16 and correlated this with the satellite-based district level PM 2.5 at the birth months of the children.


They found that a five-year-old girl born during months, when pollution peaked, would be 0.24 cm shorter than the average. The researchers kept in mind other factors that could contribute to growth in height such as nutrition and sanitation, said study authors. To quote Sagnik Dey, one of the authors of the study and associate professor at the Centre for Atmospheric Science at IIT-D, which collaborated with the University of Texas and Indian Statistical Institute for the study, “It may seem like a small change, especially when compared to the effects of other factors such as nutrition and sanitation, but the effect of ambient air pollution is experienced everywhere in the country and affects 30 million births every year. This study adds to the evidence that air pollution also affects the health and development of the next generation. The study accounted for compounding factors like the height of the mother and whether the child is born in a rural or urban setting, but the decrease in the height of children with increasing pollution levels was noted across board.”

A child’s future is pinned on the first 1000 days of development when brain growth is most rapid. Any damage during this critical period can cause long-lasting effects on their health and well-being. - Dr. Megha Consul

The study factored in the height discrepancies amongst the parents, and even with mothers who were taller a decline in height was found when pollution levels in birth months were high. This was across rural and urban children, although rural children are generally shorter on an average when compared with urban children and this could also be a factor of nutrition, lack of nutritious food, open defecation, etc.

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To quote Dey, “Other factors like malnutrition and open defecation also play a role in rural areas, but programs to address air pollution are largely urban-centric; even the National Clean Air Programme focuses on the non-attainment cities. The effects of high air pollution are felt in rural areas, where household pollution is higher due to the use of solid fuels.”

According to Dr. Megha Consul, “Unfortunately, most air pollution research targeting reproductive health has been conducted only in the past decade. Only recently has this research has begun to focus on vehicular pollution. Even more alarming is the fact that many studies have been conducted in areas that have but a small fraction of the pollution that babies and children in Delhi NCR are exposed to.”


She elaborates as to how air pollution can affect children, both in brain development as well as leading to development delays and low birth weight. “Air pollution affects the brain through several mechanisms. Particulate matter can cause swelling of the barrier protecting the brain from toxic substances. Breakdown of this barrier has been strongly linked to degenerative memory and motor disorders as an adult. Babies have been found to have proteins similar to those in adults with Alzheimer’s. Ultrafine particles smaller than 2.5microns can easily enter the bloodstream and travel to the brain. Magnetite particles can enter the body through the olfactory nerve in the nose, or the gut. Commonly found in urban outdoor air pollution, these particles are highly toxic for the brain. Polycyclic aromatic hydrocarbons (PAHs) are pollutants formed by the burning of fossil fuels and found in areas with high automobile traffic. They directly damage or reduce white matter necessary for different parts of the brain to communicate with each other when fetuses are exposed antenatally. These neural connections are the foundation for continued learning and development. Pollutants inhaled during pregnancy can penetrate into the placenta and affect the developing brain of a fetus. This prenatal exposure not only causes developmental delays but also low birth weight.”

Stunting is just not limited to the physical development of the child, but also affects cognitive development, impairs or lowers performance at school due to the effect on cognitive development, raises mortality from diseases like hypertension or diabetes later in adulthood, and more.

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“Studies have linked a number of air pollutants to adverse birth outcomes, including low birth weight (LBW) and small for gestational age (SGA), prematurity, and heart defects at birth. More recently, researchers have also begun to investigate effects on pre-eclampsia (pregnancy-induced hypertension) and spontaneous abortion, the latter possibly triggered by air pollution’s damage to DNA in sperm. The problem with all of the above, however, is that studies have been done in a far less polluted environment than we are living in at present,” says Dr. Consul. She adds, “Evidence is accumulating that environmental exposures can cause infants to be born premature (before 37 weeks of gestation) or low weight (less than 2500 grams, or 5.5 pounds), or be born with certain birth defects. These babies are far more likely to die in infancy, and those who survive have high risks of the brain, respiratory, and digestive problems in early life. The impact of environmental exposures on fetal development may be far-reaching, as data suggest growth and developmental delays in utero influence the risk for heart disease and diabetes in adulthood.”

How can expectant mothers reduce their exposure to atmospheric pollutants? Shifting out to a less polluted environment is often impossible and unrealistic. Mothers-to-be inhale atmospheric pollutants on a daily basis if they are living in highly polluted areas. What they can do, though, is to try and avoid being in areas with burning fuels, staying away from busy exhaust filled roads, use air filters and masks, etc. Even a moderate decline of exposure from high to moderate can only help the growing fetus.

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Dr. Consul suggests some good measures for parents to adopt that could possibly reduce the negative effects of exposure to high pollution. “Avoid exposure to toxic air during pregnancy. Don’t expose your baby to sunlight in the morning hours. Use an air purifier: Parents in India suffer from the myth that air purifiers decrease “immunity”. There is nothing that exacerbates the effect of toxins as compared to air pollution. Protect the mother to be from dust, use organic repellents. Not just the outside environment, parents also need to avoid dust and indoor pollution. In the monsoon weather, avoid using chemical sprays -stick with essential oils and natural substances. Breastfeed your baby. Don’t smoke and keep second-hand smoke out of your home. During pregnancy, don’t paint or use cleaners with strong smells. Aside from not burning fuels inside the home, voting— and lobbying politicians in power—may be the single most effective recourse a concerned parent has for reducing the amount of air pollution to which their child is exposed.”

The last point bears notice. It is with the vote, and the demanding of policies and their implementation from the authorities that would control levels of pollution perhaps that citizens could best combat the menace of pollution. We owe it to our children to give them a chance to breathe air that doesn’t threaten their growth and wellbeing.

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Kiran Manral is the Ideas Editor at SheThePeople.TV

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