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Issue May 2023

What’s in the air?
Smog

The term smog was coined at a Public Health Congress in London in 1905.

It is a portmanteau of smoke and fog. At the beginning of the 20th century, a heavy haze so often lay over what was then the largest city in the world that the phenomenon was even nicknamed a “London Peculiars”. In December 1952, several thousand people died as a result of respiratory problems and airborne toxins during The Great Smog in London.

Smog is air pollution caused by emissions from traffic, industry, and private households. It therefore mainly occurs in densely populated areas.

The composition varies depending on the respective emission sources. Most smog contains soot, fine dust, water in the form of fog, nitrogen oxides, and sulfur dioxide. The latter reacts with the water and forms secondary pollutants such as sulfuric acid and sulfurous acid.

Winter smog

Winter smog is caused by a stable inversion, in which the air is stuck and cannot circulate as usual. This allows pollutants accumulate in the air over a longer period of time.

Summer smog

Photochemical smog, also called summer smog, occurs when nitrogen oxides, carbon monoxide, or volatile organic compounds react to form ozone, aldehydes, or nitric acid as a result of UV radiation during periods of fine weather.

Haze

The third commonly mentioned form of smog is haze. It is typically made up of dry dust caused by forest fires and predominantly affects countries in southeastern Asia.

What are the risks of smog?

The contaminants in smog pose a serious health risk.

Symptoms range from irritation of the mucous membrane and coughing to heart attacks and lung cancer. The sulfur compounds contained in winter smog in particular cause irritation of the respiratory tract and eyes. They are so aggressive that they also cause damage to plants and buildings. Ultra-fine particles contained in smog can also penetrate deep into the lungs and even enter the bloodstream, causing inflammation, blood clotting disorders, and damage to the nervous system. People with chronic lung and cardiovascular diseases are particularly at risk.

What can we do about smog?

Since the emissions associated with smog come from multiple sources, there are also many ways to mitigate it:

Industrial plants and power stations

Use highly efficient dust removal solutions and switch to clean energy production.

Transport

Switch to electric cars or public transport to limit the use of combustion engine vehicles.

Private households

Use heat pumps instead of oil heaters, swap petrol-powered lawnmowers, etc. with electric alternatives.

It is possible to minimize health risks — particularly indoors, but powerful cabin air filters can also ensure clean air in cars and buses. These filters almost completely remove particles such as soot, fine dust, aerosols, and contaminant gases from the intake air and provide reliable smog protection for passengers.

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