The number of children who develops asthma is skyrocketing around the world and researchers believe that the trend is due to traffic pollution.

A new study examined childhood asthma incidence and levels of nitrogen dioxide, which comprises 80 percent of emission from vehicles, across 194 countries and 125 major cities. They found that 13 percent or 4 million cases of new childhood asthma diagnosed every year can be linked to exposure to traffic pollution, particularly nitrogen dioxide.

"Nitrogen dioxide pollution appears to be a substantial risk factor for childhood asthma incidence in both developed and developing countries, especially in urban areas," stated Susan Anenberg, the senior author of the study published in the journal The Lancet Planetary Health.

New Cases Of Childhood Asthma Rising

Kuwait has been identified as the worst offender, reporting 550 new cases of asthma due to traffic pollution per 100,000 children. The United Emirates came second with 460 new cases per 100,000 children followed by Canada in third place with 450 new cases per 100,000 children. The United States trailed behind at no. 22 out of 194 countries with 300 new cases per 100,000 children.

By city, Lima, Peru has the highest rate of new childhood cases of asthma due to traffic pollution. It is followed by Shanghai, China, and Bogotá, Colombia in the second and third spot respectively.

Los Angeles and New York landed on the eighth and ninth place with 530 new traffic pollution-related cases of childhood asthma per 100,000 children

Traffic Pollution: A Threat To Public Health

The World Health Organization declared air pollution as a major environmental risk to health in low, middle, and high-income countries. The current guideline suggests that the annual average nitrogen dioxide concentrations should stay below 40 μg/m3 in order to protect the public from the harmful effects of the gas.

However, the researchers said that 92 percent of the cases develop in areas that stay below the recommended annual average nitrogen dioxide. They believe that the findings should encourage the WHO and public health officials to reconsider the current guidelines and find a way to mitigate the exposure of children to traffic pollution.

"Our study indicates that policy initiatives to alleviate traffic-related air pollution can lead to improvements in children's health and also reduce greenhouse gas emissions," explained Ploy Achakulwisut, lead author of the study. "Recent examples include Shenzhen's electrification of its entire bus fleet and London's Ultra-Low Emission Zone congestion charges."

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