india

Updated: Oct 30, 2018 00:04 IST

India recorded the highest number of air pollution-induced deaths of children below five years in 2016, according to a World Health Organization (WHO) report that analysed the impact of toxic air on the health of children in 194 countries.

At least 100,000 children below five years died that year in the country due to health complications associated with high outdoor and indoor air pollution, according to the report titled ‘Air Pollution and Child Health’ released in Geneva on Monday.

Nigeria (98,001), Pakistan (38,252), Democratic Republic of Congo (32,647) and Ethiopia (20,330) followed India, completing the list of the worst five countries in child mortality in the study.

Death rates, or the ratio of deaths to population during a particular period, were higher in these four countries than that of India.

Of the countries surveyed, India recorded the highest premature deaths among children under five years due to outdoor air pollution in 2016 and the second highest number of deaths due to exposure from indoor air pollution — only after Nigeria.

About 98% of the children in that age group in India are exposed to PM2.5 levels that exceed WHO’s annual standard of 25 micrograms per cubic metres. PM2.5 pollutants are particulate matters that have a diameter of less than 2.5 micrometers.

These tiny particles are so fine that they can enter the bloodstream and lodge deep into the lungs.

Half of all deaths due to acute lower respiratory infections, which include pneumonia and influenza, in children below five years is caused by exposure to high air pollution levels in low- and middle-income countries, estimates WHO.

Across the world, at least 600,000 children died from acute lower respiratory infections caused by air pollution in 2016.

India also has one of the highest morbidity and mortality rates: at least 50 deaths for every 100,000 children due to such infections.

Globally, premature birth is the only other factor that kills more children below five years than acute respiratory infections. In the African region, however, acute respiratory infections are the leading cause of death of children in that age group.

When asked about the details of the methodology for the country-wise mortality figures, WHO said the sources to assess PM2.5 exposure was scientific modelling, ground measurements (provided by the likes of the Central Pollution Control Board in India) and satellite data. The methodology to assess risks associated with PM2.5 exposure is the one used in the Global Burden of Disease, a study on health impacts from various sources.

WHO has also put together a list of health effects that children may be facing from air pollution, taking into account significant research studies published in the past 10 years and inputs from experts around the world.

Poor birth outcomes like low birth weight and a rise in pre-term births and stillbirths due to the mother’s exposure to high air pollution levels have been mentioned in past research.

WHO’s review has established that air pollution can also lead to behavioural disorders such as autism spectrum disorders and attention deficit hyperactivity disorder; adverse metabolic outcomes such as obesity and insulin resistance; occurrence of otitis media (an inflammatory disease of the middle ear); and higher risk of retinoblastoma (cancer of retina) and leukaemia (blood cancer) in children.

The report says that there is substantial evidence that exposure to road traffic-related air pollution or diesel exhaust is associated with childhood leukaemia.

Authors of the study have listed why children are the most vulnerable to air pollution exposure and the various pathways through which air pollution affects their health — which include inhalation and ingestion of pollution particles.

As children breathe at twice the rate that adults do, they inhale larger amounts of air pollutants. Pollution particles are also moved through the respiratory system faster, allowing them to reach the lungs, the alveoli and the bloodstream more rapidly, according to the study.

Children are also more physically active than adults; so their ventilation is even greater. They are closer to the ground, where pollution concentrations are higher. Certain pollutants (small enough to penetrate the alveolar wall) inhaled by a pregnant mother can enter her bloodstream and then cross the placental barrier and reach the foetus, and, in turn, affect the baby’s growth and development.

Children are also exposed to pollutants through mother’s milk. Pollutants from industrial sources, such as pesticides, fossil fuels, chemical by-products, flame retardants, heavy metals and volatile organic compounds, can enter the mother’s circulation by inhalation or, more commonly, ingestion before being passed into breast milk, the report says. For example, polycyclic aromatic hydrocarbons (PAHs), a toxic and carcinogenic compound, have been reported at high levels in breast milk samples in the Mediterranean.

WHO finds a strong correlation between poverty and exposure to air pollution. Children in low-income communities suffer disproportionately higher effects of air pollution. “Poverty causes people to rely on polluting energy sources for their basic needs, and poverty compounds the health risks associated with their use. Poverty also limits people’s capacity to improve the environment in which they raise their children,” the report says. Female children are worst affected, and more girls than boys die premature due to air pollution in India, says WHO data.

Dr SK Chhabra, head of department (pulmonary, sleep and critical care medicine) at Primus Super Speciality Hospital, is not surprised with the WHO findings. He led a study last year at the Vallabhbhai Patel Chest Institute, which found that children in Delhi have a far lower lung capacity and lung growth rate compared to children of the same age in the United States.

“We have already reported that lung growth rate among Indian children is retarded. Nutritional deficiencies, protein and vitamin D deficiencies only compound the problem. Our experience shows that children under five are more impacted by indoor air pollution because of biomass burning within the house.”

Dr Rahul Nagpal, paediatric consultant with Fortis hospital, said: “The first impact of air pollution is seen on the respiratory system. We see a lot of allergies, infections and prolonged cough and slow response to conventional medication. Otitis media is linked to respiratory disease. The nose and ear are both affected by pollution. The infections significantly go up during this season. Till now about 50% of the hospitalisation cases till now were dengue related now almost all are linked to respiratory infections.”