07 May 2019 Story Air

Asthma sufferers need to be ultra-wary of air pollution

Photo by LibreShot

An asthma attack is a frightening experience, threatening to deprive you of your ability to breathe, and life itself. According to World Health Organization estimates, 235 million people suffer from asthma, which is the most common chronic disease among children. Over 80 per cent of asthma deaths occur in low and lower-middle income countries.

World Asthma Day on 7 May 2019 reminds us that people with chronic respiratory problems are particularly vulnerable to all forms of air pollution.

One form of pollution that particularly affects people in cities is transport emissions.

“Living by London’s busy A2 road, which carries thousands of cars, lorries and coaches, I often worry about the impact air pollution has on my health,” says asthma sufferer Tom Bartlett, 24. “I don’t feel comfortable cycling or running nearby and use back roads whenever I can to avoid the fumes.” 

A new study says vehicle pollution results in 4 million child asthma cases a year, equivalent to 11,000 new cases every day. The research, published in the journal Lancet Planetary Health, is the first global assessment of the impact of traffic fumes on childhood asthma based on high-resolution pollution data. The key pollutant, nitrogen dioxide, is produced largely by diesel vehicles.

“This is an important study and shows just how dangerous vehicle emissions are for children in urban areas,” says Soraya Smaoun.

Heavy traffic in Manila, Philippines. Photo by Judgefloro/Wikimedia Commons

Risk factors for asthma

The strongest risk factors for developing asthma are a combination of genetic predisposition with environmental exposure to inhaled substances and particles that may provoke allergic reactions or irritate the airways.

Aggravating factors for asthma sufferers can be indoor allergens such as house dust mites in bedding, carpets or pet dander; outdoor allergens such as pollen; and tobacco smoke.

“Urbanization has been associated with an increase in asthma. But the exact nature of this relationship is unclear,” says the World Health Organization.

During an asthma attack, the lining of the bronchial tubes swells, causing the airways to narrow and reducing the flow of air into and out of the lungs. Recurrent asthma symptoms frequently cause sleeplessness, daytime fatigue, reduced activity levels, and school and work absenteeism.

The girl in London whose death may have been linked to air pollution was an asthma sufferer who lived in Lewisham, 25 metres from London's South Circular Road—a notorious pollution "hotspot". Her mother is fighting to open a fresh inquest that will list air pollution as a causative factor on the death certificate.

Because children are shorter than adults, they are closer to the ground and therefore to the exhaust pipes of vehicles. Additionally, young children breathe faster, meaning they take in more air relative to their body weight.

Nairobi, Kenya: Buses often leave their engines running to attract customers. Photo by Jack Kavanagh/UN Environment

Nitric oxide (NO) and Nitrogen dioxide (NO2), collectively called NOx, are emitted from petrol and diesel vehicles, and energy generation. They are major pollutants causing heart disease and respiratory illness and are still escalating rapidly in developing countries.

Statistically, nine out of 10 people worldwide are exposed to levels of air pollutants that exceed World Health Organization safe levels. According to the United Nations Children’s Fund, 17 million babies around the world are breathing toxic air.

What can be done?

Municipalities can establish clean air zones for kids who walk to school and minimize vehicle traffic along certain routes. Globally, air pollution can be reduced by switching to renewable forms of energy and heavily reducing the emissions in the transport sector. Planting trees is also very important. Making these changes now is vital to ensure that our children aren’t burdened with irreversible health issues that limit their futures.

 Learn more about the global #BreatheLife campaign, led by the World Health Organization, UN Environment and the Climate & Clean Air Coalition, which supports a range of cleaner air initiatives that cover 55 cities, regions, and countries, reaching over 153 million people.


Air pollution is the theme for World Environment Day on 5 June 2019. The quality of the air we breathe depends on the lifestyle choices we make every day. Learn more about how air pollution affects you, and what is being done to clean the air. What are you doing to reduce your emissions footprint and #BeatAirPollution?

The 2019 World Environment Day is hosted by China.


The UN Climate Action Summit will take place in New York City on 23 September 2019 to increase ambition and accelerate action on the global climate emergency and support the rapid implementation of the Paris Climate Change Agreement. The 2019 UN Climate Action Summit is hosted by UN Secretary-General António Guterres.