How smog and air pollution cause long-term health problems – DW – 11/22/2024

All 100 of the world’s most polluted cities are in Asia. In November 2024, severe air pollution persisted in major Indian cities, including New Delhi, and parts of Pakistan. Local residents were advised to stay home and construction work at schools and outdoors was suspended due to winter smog.

But air pollution is nothing new in the world’s most densely populated and built-up cities. And exposure to air pollution can happen anywhere: whether a person is walking through a city full of factories, stuck in rush hour traffic, or in rural areas where wood fires are used for heating.

However, for many people in the hardest-hit parts of the world, taking precautions to avoid poor air quality is easier said than done.

What causes air pollution and how does it turn into smog?

Smog is a mixture of the words “smoke” and “fog.” This should give you an idea of ​​how this dirty chemical haze is created.

It is formed when ground-level pollutants such as ozone, particulate matter, sulfates, nitrates and other toxic chemicals combine with fog under sunlight.

Why is smog and air pollution dangerous?

Smog and pollution are dangerous because they are easy to inhale.

Combustion processes—whether in an industrial plant, in your car engine, or in the furnace of a home wood-burning fireplace—release toxic gases into the atmosphere.

Often suspended in smoke and gas are microscopic particles created by complex chemical reactions between the substances we burn.

Solid particles are labeled by size. For example:

• PM10 for particles 2.5-10 micrometers in size
• PM2.5 for particles 2.5 micrometers or smaller
• PM0.1 for ultrafine particles less than 100 nanometers

These particles are tiny. In comparison, human red blood cells are the size of PM10 as they are around 6-8 micrometers in diameter.

Bacteria, for example, pathogenic coli, are about 3 micrometers wide, so PM2.5 is even smaller.

As for ultrafine PM0.1, these particles are even smaller than the viruses that cause influenza and HIV.

It is because of their microscopic size that inhaling these chemical particles, consisting of toxic gases, heavy metals and volatile organic compounds, can easily be absorbed into the bloodstream where they can cause long-term harm.

How do smog and air pollution affect health?

Inhalation of particulate matter and polluting gases has long been associated with poor health and a range of diseases and disorders.

Short-term exposure may worsen acute conditions such as asthma and other respiratory problems and infections, as well as impair lung function.

In the long term, chronic diseases may occur, including cancer, strokes, heart disease and obstructive pulmonary disease.

It can affect people of all ages, but children and people over 65 are especially vulnerable.

In May 2024 study of low emission zones in Germany found that children who were exposed to clean air from conception to the first year of life were less likely to need medication before the age of five.

“Exposure to air pollution very early in life can have long-term consequences as children grow older,” said Hannah Klauber, lead researcher of the study.

Previous research has also shown that children exposed to pollution early in life do worse in school, have lower test scores and, on average, earn less income as adults.

“A number of studies have shown that there are no safe levels of air pollution,” Klauber told DW. “There are virtually no safe levels of particulate matter, so any increase in particulate matter results in adverse health effects.”

Although Klauber’s study focused only on Germany, Klauber said she expects to find similar results in other countries around the world.

How is air quality assessed and why?

Air quality ratings are used to monitor air pollution levels in an area.

Such rating scales are usually developed by national governments, so standards may vary from country to country. But many of them are based on global recommendations from the World Health Organization.

Some countries and cities have color-coded quality ratings. For example, in the USA and India:

• Green color means good air quality.
• Yellow – for moderate pollution.
• Orange – poor air quality
• Red indicates very poor air quality.

What can you do to protect yourself from smog?

There is little you can do to effectively protect yourself from smog if you are in a situation where you cannot avoid it.

But in some cities with high levels of pollution, such as New Delhi and Lahore, authorities are imposing restrictions on outdoor activities. This includes the closure of schools, restrictions on driving cars and other vehicles, and the suspension of outdoor activities.

Cities prone to smog and high air pollution can also advise residents to use filtration mechanisms where possible and reduce physical activity.

Does closing schools help reduce air pollution?

No, not according to Rajib Dasgupta, professor of public health at Jawaharlal Nehru University in New Delhi. Dasgupta told DW that restrictions on outdoor activities or school closures were only temporary measures.

“This is something that cannot be dealt with through intervention at a personal or family level. This is something that must involve government action and very large-scale cross-sectoral action,” Dasgupta said.

Measures are being taken around the world to tighten air pollution limits. The European Union agreed on new standards in June 2024, and in Asia, efforts to reduce air pollution are also underway in some of the hardest-hit places, such as Beijing, China.

Beijing authorities presented a plan to electrify public transport in 2013. This has led to a significant reduction in smog and pollution, but levels still exceed government and global air quality guidelines.

India has also adopted a new clean air policy, but Dasgupta criticized the lack of progress: “States seem to be unable to get their act together, and it’s not because of a lack of money, but because of a lack of will.”

Editor: Zulfiqar Abbani

Select sources:

WHO Global Air Quality Guidelines (2021)

Study: “The Soft Murder of Recipes” published by Klauber, Hanna, Felix Golub, Nicholas Koch, Nico Pestel, Nolan Ritter and Alexander Rolfe in the American Economic Journal Economic Policy (2024) DOI: 10.1257/pol.20210729