A few days ago, a five-year-old boy from Kathmandu was rushed to the emergency ward of the Kanti Children's Hospital for a respiratory illness. Doctors said the boy had been suffering from an acute lower tract infection, decreased lung function, and asthma.

“Respiratory viruses, including influenza and others, become more active during the winter season,” said Dr Sumit Agrawal, the hospital spokesperson. “The rise in the air pollution levels has further exacerbated the problems.”

This has become a common refrain among the hundreds of children suffering from respiratory illness, as the air quality in the country continues to decline.

Doctors say respiratory viruses—influenza A(H1N1), A(H3), influenza B, rhinovirus, coronaviruses, and adenoviruses, among others—are generally more active during winter. But what alarmed them is that studies show children in Kathmandu Valley are highly exposed to air pollution, which could worsen respiratory and other problems.

A recent study carried out by the Nepal Health Research Council shows that children in Kathmandu Valley have been highly exposed to air pollution.

“They are exposed to air pollution while commuting to and from school,” said Dr Megnath Dhimal, chief researcher at the Council. “Those travelling by scooter to and from school are at risk even more.”

According to the report, KN95 masks block 50 to 70 percent of pollution particles, but most children do not wear these masks. Parents, too, are often not aware of the risks. Moreover, children do not know how to wear face masks properly.

With the start of the dry season, air quality, mostly in highly dense cities, including the Kathmandu Valley, has been worsening.

IQ AirVisual, a Swiss group that collects air-quality data from around the world, has ranked Kathmandu among the world’s 10 most polluted cities several times in recent days.

PM2.5 refers to particulate matter (solid or liquid droplets) in the air that is less than 2.5 micrometres in diameter. It is among the most dangerous pollutants that can get past the nose and throat to penetrate the lungs and even the bloodstream. PM2.5 particles are small and are also likely to stay suspended in the air for long, increasing the chances of people inhaling them.

Doctors say poor air quality can cause short- and long-term effects on public health. In the short term, it can lead to pneumonia, bronchitis, conjunctivitis, skin allergy, stroke, and heart problems, and in the long run, it can lead to severe conditions like ulcers, cancer of the lungs and intestine, kidney disease, and heart complications.

“The increase in the sale of inhalers and nebulisers for children is also a clear sign of how serious the problem has become,” said Dr Ganesh Rai, former director at the Kanti Children Hospital. “The number of cases of respiratory illness in children has risen by 50 percent in the last 10 years and 100 percent in 20 years.”

Studies show people in low- and middle-income countries get disproportionately affected by polluted air, which is responsible for more than 90 percent of deaths in these countries, according to the World Health Organisation.

Several studies carried out in the past in Nepal also showed that toxic air takes a huge toll on public health. Along with respiratory illness, the toxic air has led to severe conditions like ulcers, cancer of the lungs and intestine, kidney disease, heart complications, high blood pressure and stroke, according to experts.

Past studies also show that polluted air has been shortening people’s lives. Nepali lives are being cut short by around five years, according to a report by the Air Quality Life Index (AQLI), which converts air pollution concentration into an impact on life expectancy. AQLI is a metric produced by the Energy Policy Institute at the University of Chicago.

Toxic air is deadlier than tobacco use and high blood pressure, which reduce life by 2.8 years and 1.7 years, respectively, according to the report.

Public health measures—mask-wearing, handwashing, avoiding crowds, and maintaining social distancing—can reduce infection, according to doctors.