What is smog, how is it formed and why is it harmful

Smog regularly covers the central part of our country, and the summer of 2022 was no exception. We understand what it is, why it occurs and what does climate change have to do with it

What is smog

Smog is increased air pollution, an aerosol consisting of smoke, fog and dust. Evgenia Naumova, project coordinator of the Russian branch of Greenpeace, emphasizes that smog is characterized by increased concentrations of pollutants – fine particles (the so-called PM2.5 and PM10), soot, carbon monoxide, and nitrogen oxides.

The invention of the term is attributed to the physician Henri Antoine de Vaux, who in 1905 used it to characterize the state of the atmosphere in cities. However, the word “smog” first appeared in an American newspaper in 1880. It was formed from two English nouns – smoke (“smoke”) and fog (“fog”).

Types of smog

Photochemical (summer) smog

Summer smog is formed due to the fact that chemicals from harmful emissions (nitric oxide and a number of volatile organic compounds) react with the sun’s rays. Because of this, a brown fog forms over the cities. It is also called “Los Angeles”, as this city combines historically strong vehicle emissions with heat.

Sulfuric (winter) smog

In winter, the air in cities is filled with waste from burning fossil fuels to heat homes and businesses. The problem is exacerbated by inversion, an atmospheric phenomenon in which air temperature rises as altitude increases, and not vice versa. Under normal conditions, smoke from a fire, for example, will go up, and under inversion it will spread along the ground. The same thing happens with other harmful emissions – they remain in the atmosphere, where they enter into chemical reactions and form haze. It is called “London smog”, as it has historically been present in the capital of Great Britain.

For the first time, King Edward I took care of this problem in 1306 and issued a temporary ban on coal burning. However, the consumption of fossil fuels only increased, which was especially spurred on by the industrial revolution. Londoners in the 1952th and first half of the 4th century suffered particularly from sulfur smog, which, due to its thickness and yellow color, was compared to “pea soup”. In XNUMX, XNUMX citizens died from the Great Smog, after which legislative acts were adopted to limit the burning of dirty fuels.

In addition to the two main types, there are less common types of smog, says Olga Kovaleva, an analyst at CityAir, which monitors urban air quality.

Volcanic smog

I also call him wog. Particles released into the air during a volcanic eruption react with sunlight, oxygen and water vapor to form caustic chemicals. Despite its rarity, vogue is a rather dangerous phenomenon. For example, the eruption of Mount Tamboru in Indonesia in 1815 resulted in a wave of abnormal summer frosts. The crops died, causing famine in the United States, Canada and Northern Europe.

Alaskan ice smog

It is formed at temperatures below -30°C, high humidity and no wind. Various pollutants easily attach to ice crystals formed in the air and remain in suspension.

Causes of smog

According to Evgenia Naumova, smog traditionally appears as a result of the use of carbon fuel in transport, industry, thermal energy, as well as due to the combustion of biomass or any carbon-containing material. In addition, forest, grass and peat fires cause smog. Let’s talk about these and other factors in detail.

coal burning

The combustion of coal results in emissions of smoke, particulate matter, heavy metals and chemical compounds – sulfur oxide, nitrogen oxides, carbon dioxide. It most often contributes to the formation of winter smog. Coal burning is a major contributor to air pollution in China, often causing city governments to close roads, schools and airports during the cold season.

Transport emissions

The operation of internal combustion engines leads to emissions of carbon dioxide, nitrogen oxides, volatile organic substances and hydrocarbons. Entering into the atmosphere in chemical reactions with each other and with the sun, they create summer smog.

Building

Large construction sites contribute to the release of a huge amount of dust. In addition, the use of technology leads to the formation of emissions. This contributes to the appearance of smog in both winter and summer.

Burning crops

Many farmers around the world set fire to their fields at the end of summer. This allows you to clean the land from the remnants of the last crop, fertilize it with ashes and prepare it for new sowing. This creates smoke that contains black carbon – PM2.5 particulate matter from carbon. They pollute the air and can lead to smog.

Plants

Plants and trees emit volatile organic compounds (VOCs) and hydrocarbons, which combine with the sun’s rays to create summer smog. Therefore, greening the city, paradoxically, can worsen the air quality during hot seasons.

How smog is linked to climate change

With climate change, the risks of fires are increasing and the amount of smog is increasing. In addition, an increase in temperature improves photochemical reactions and increases the number of particles in the air, contributes to the formation of smog and clouds. This is because a warmer layer of the atmosphere is located above the city and prevents colder and denser air from mixing with it normally. The environment remains still and over time, the concentration of pollutants increases, forming smog.

At the same time, smog itself also affects the climate through the so-called “black carbon” – fine particulate carbon particles that are found in the smoke of natural fires and vehicle exhausts, especially diesel fuel. Black carbon, due to its size, can travel thousands of kilometers in the atmosphere and fall out, among other things, on the ice cover of the Arctic Ocean and Greenland. This leads to a change in the reflectivity of the Arctic Ocean. The lower it is, the more the surface absorbs solar radiation. Ice and snow, becoming less white, begin to absorb heat rather than reflect it into space, which contributes to global warming, Naumova states. It turns out a vicious circle: smog causes climate change, and this, in turn, increases smog.

How dangerous smog is and how to protect yourself

Air pollution resulting from smog is particularly harmful to children and the elderly. It can reduce lung function, cause shortness of breath, wheezing, and cough. In addition, it can lead to:

• the development of asthma;
• increased risk of developing cancer;
• Alzheimer’s disease;
• birth defects in children;
• weight loss in newborns;
• increase in pressure;
• increased risk of stroke.

To reduce the impact of smog on the body, you should adhere to the following rules:

• follow weather forecasts;
• in case of smog, do not go out and try to avoid especially polluted parts of the city;
• do not play sports during smog;
• avoid traveling by car, as there is a risk of getting stuck in a traffic jam;
• if necessary, wear FFP3 respirators.

How to deal with smog

Evgenia Naumova believes that the first thing to do is to prevent forest or peat fires. It is necessary to monitor the use of fire: extinguish fires, do not throw cigarette butts on the ground. If you solve the problem of wildfires at the system level, then you need to tell children about the rules of behavior in nature, and you can also become a voluntary forest firefighter.

Many Western countries have passed laws aimed at combating smog. Some of these include restrictions on what chemicals factories can release into the atmosphere. Some cities have special days on which residents can burn waste, such as leaves in the yard. These measures reduce the amount of pollution, but this is still not enough. To completely get rid of smog, a whole package of environmental solutions is needed.