THE GLOBAL HISTORY OF SMOG

As the London experience aptly demonstrates, a prolonged period of calm with zero wind is not required. For a large city, even a few weeks suffice, a condition easily facilitated by any sufficiently large anticyclone—a high-pressure area that brings calm weather conditions with strong frost in winter and intense heat in summer.

‘A blocking anticyclone “locks” air masses, disrupting atmospheric circulation and preventing the movement of polluted air. Since new pollutants constantly enter from the surface of the ground, there is an accumulation of impurities and an increase in the concentration of pollutants,’ explains Dina Gubanova from the A.M. Obukhov Institute of Atmospheric Physics of the Russian Academy of Sciences.

‘To stop vertical air mixing, or convection, inversion is needed. In the lower part of the atmosphere (the troposphere), where we live, the air temperature decreases with height,’ says Gubanova, ‘and so vertical mixing exists: the lower layers of air are heated from the surface and move upwards, gradually cooling. But sometimes, this mechanism breaks down, and a warmer layer of air forms at altitude. This is called inversion, a “reversal” of the normal position of air layers.’

According to Gubanova, the most common type of inversion is radiation inversion. It occurs during calm, cloudless weather, typically at night. After sunset, the surface begins to cool down, and the lower layers of air cool down with it. The layers above, however, do not have time to cool and retain their heat. At sunrise, the warming of the air and the earth's surface disrupt inversion, a process that even a slight wind of 2–3 meters per second can interfere with.

However, if there is no wind and the surface is covered by fog or haze formed overnight, the inversion can persist for a long time due to the absence of sunlight. This type of effect is considered one of the main mechanisms of a nuclear winter. Soot from numerous fires caused by nuclear explosions would rise high into the atmosphere; its particles would be heated by the rays of the sun, warming the air around them, resulting in a warm layer at a high altitude. However, the air would cool rapidly underneath it since it is isolated from the sun.

A ‘miniature nuclear winter’ occurred in London in December 1952. Fog, formed from the cooling ground overnight and combined with smoke, shielded the city from the sun, preventing the lower layers of air from warming up and trapping air in the city.

Gubanova explains that scientists make a distinction between two main types of smog. The first, as mentioned by Harold Antoine Des Voeux, is called ‘classical’ or ‘London’ smog, which is a mixture of coal combustion products and water vapor, essentially coal smoke combined with fog. It occurs at relative humidity levels of over 70–80 per cent during cold, windless weather.

Coal is primarily made up of carbon. The higher the carbon content, the higher the quality of the coal, ranging from 76 per cent for low-grade coal to 90 per cent for anthracite. When coal burns, it produces carbon dioxide, which, while contributing to climate change, is not inherently harmful to health. However, incomplete combustion due to insufficient oxygen can produce toxic carbon monoxide (CO) and unburned particulate matter, with the most significant harm coming from its impurities.

Low-grade coal may contain a significant amount of impurities, such as sulfur compounds and iron (FeS2). Some types of coal can contain up to 6 per cent sulfur, which, when burned, turns into sulfur dioxide (SO2). Sulfur dioxide enters the moist atmosphere and, in the presence of iron and manganese acting as catalysts, transforms into sulfuric acid droplets (H2SO4). These acidic droplets, along with particulate matter, carbon monoxide, and nitrogen oxide, form the infamous ‘pea soup’ smog.

The residents of Los Angeles in the US first encountered the second type of smog, ‘dry smog’, on 26 July 1943, when the city was enveloped in a haze that irritated the eyes and caused nasal congestion. Initially, residents thought they were under a chemical attack by the Japanese army. However, this chemical effect was self-inflicted—it was a photochemical smog. The main component of this type of smog is automobile exhaust.

When fuel burns in engines, nitrogen oxide (NO) is formed. Upon entering the atmosphere, it converts to nitrogen dioxide (NO2). In the presence of sunlight, it breaks down into nitrogen oxide and atomic oxygen, which is highly reactive and turns into ozone. While ozone is often praised for protecting us from ultraviolet radiation, it is beneficial only when it is at high altitudes, for example as part of the ozone layer. Tropospheric ozone, the ozone that can enter our lungs, is a toxic substance.

In addition to ozone, photochemical smog comprises organic compounds, remnants of unburned fuel, nitrogen oxides, nitric acid droplets, carbon monoxide, and various other toxic substances that are unsafe to breathe. Statistics indicate that until the 1980s, approximately 10,000 people per year succumbed to diseases linked to air pollution in California, prompting US authorities to take substantial measures to tackle this issue.

Since the mid-twentieth century, the smog problem in European and American cities has become less acute. People have learned to mitigate the harm caused by emissions; power plants and boilers switched from coal to gas; factories have installed filtration systems; and overall, industrial enterprises gradually began to move outside major cities. Environmental standards regarding automobile and industrial emissions have become stricter every year. While the air in major metropolises can hardly be called clean, disasters like the London smog of 1952 are now unlikely. The problem of chemical anthropogenic smog has shifted to Asian countries, where it has proved to be much more acute than in Europe and North America.

A Russian journalist painted the winter scene in Kabul in 2010 in these words, ‘After 5 p.m. local time, venturing outdoors without risking one's health became nearly impossible. Swirls of blue smoke linger in the air, like a lilac fog that, unfortunately, doesn't dissipate but poisons everything alive until around 9 a.m.’

Scientists consider this city of 5 million people one of the most polluted on the planet. However, this was not just because Kabul is located in a mountain valley that hinders air movement; the difference between Kabul's smog and London's was qualitative—chemical.

A significant portion of Kabul's population consists of refugees from across the country, settling on the outskirts of the city in self-built shanty towns made of adobe structures, where there was neither electricity nor sewage. Home-made camping stoves are used for heating and burning practically anything combustible: dung, wood, plastic waste, rags, and even car tires. Public baths, which are very popular, are often heated with garbage. It's difficult to predict what gets into the atmosphere with the smoke from such unconventional fuel.

The second issue concerns transportation. Afghanistan continues to utilize cars manufactured in the Soviet era. Emissions from worn-out engines are significantly more dangerous and harmful than those from new cars in European cities. Currently, there are about 5,000 cars in Kabul, and according to scientists' estimates, they are responsible for 36 per cent of all emissions into the atmosphere. The numerous diesel generators in the city also contribute to emissions.

Another problem is the lack of greenery and paved roads. Transport kicks up a huge amount of fine dust into the air. In winter, Kabul often experiences all the conditions for smog—atmospheric inversion, fog, zero winds, et cetera—but unlike the London smog of 1952, the air in the Afghan capital contains a huge variety of additional components from ammonia to ozone.

Yet, Kabul is not alone in experiencing these problems. Rapid urbanization, population growth in cities, the proliferation of automotive transport with very weak infrastructure, and poverty have affected almost all major cities in Africa and Asia. No air composition measurements are conducted in many of these places, and scientists have to rely on indirect data to make their assessments and calculations.

Using satellite data on air composition from forty-six rapidly growing cities in the tropics, a team of British and American scientists concluded that around 180,000 people died in these cities in 2018 due to increased air pollution. However, this estimate seems relatively moderate compared to a World Bank report, which estimated that 2 million premature deaths occur annually in South Asian cities due to air pollution and called for urgent action to reduce emissions and mitigate harm.

Raisa Semenova dedicated her entire life to treating lung diseases after she left the Almaty Medical Institute. She was a highly skilled physician, renowned for her teaching and respected for her research, chairing the Central Asian Pulmonology Congress in 1996. However, her 1988 research extended beyond the scope of medicine as Semenova managed to investigate how continuous air pollution affects the health of urban dwellers.

It seems self-evident that breathing diluted smoke from coal-fired boilers and automobile exhaust cannot be harmless. This was vividly proved by the London smog of 1952 and many similar events. But what if a low and constant level of air pollution, not reaching catastrophic levels, could be relatively safe? Could it be that against the backdrop of harm from alcohol, smoking, sedentary lifestyles, and high-calorie fatty foods, the damage from atmospheric pollution would go unnoticed? For Semenova, this was not merely a theoretical inquiry as her city, Almaty, ranked among the top twenty most polluted cities in the Soviet Union in the 1980s.

Typically, scientists address such questions through experiments. They place test animals in a controlled environment and then remove the factor under investigation for one group while leaving it intact for another (the control group), while leaving all other conditions for both groups identical. In our case, we would have to expose one group of people to polluted air while freeing the other group from it. However, this would need to be done in a way that ensured all living conditions for both groups were the same: the same food, the same housing, the same percentage of smokers, and so on.

However, ethics prohibit conducting such experiments on humans, and so Semenova pursued a different approach. She selected three zones in Almaty with varying levels of air pollution. Zone X had relatively clean air, Zone Y had moderate pollution levels, and Zone Z had highly polluted air. Each zone had a population of 21–24,000 people, and the zones were chosen so that other living conditions—such as the number of floors in residential buildings, water quality, and noise level—were the same, with only air quality differing in each. In Zone Z, the most polluted, Semenova used a hypothetical air pollution coefficient, Ksum, ranging from 12–15 units. In the zone with moderate pollution, Y, it was about 9, and in the clean zone, it was around 3.9. This meant that the air in the ‘dirty’ zone was three to four times worse.

Over five years, Semenova's team replicated and analyzed the outpatient records of residents from all three zones. In total, the researchers gathered data on the health status of approximately 50,000 people to determine how much more often people in the ‘dirty’ zone suffered from non-specific lung diseases, such as chronic bronchitis, pneumonia, pleurisy, and other respiratory organ dysfunctions.

In addition to analyzing written data, the medical team interviewed 980 people from each zone to determine how other factors, such as smoking and dietary habits, influenced their health. Finally, 1,900 people underwent in-depth clinical examinations. Substantial differences were already noticeable during the survey phase. Residents of Zone Z complained much more frequently about air pollution and suffered more often from dizziness, headaches, nausea, and vomiting.

The analysis of medical records confirmed this difference too. In Zone Z, lung diseases were diagnosed significantly more often than in Zone X, with 160 cases per 1,000 people as compared to 107 cases. Moreover, this difference persisted even when individual diseases were analyzed. Zone Z had far more cases of both acute and chronic bronchitis, acute pneumonia, and bronchial asthma. For example, the number of pneumonia cases in Zone Z was twice as high as in Zones X and Y, and chronic bronchitis occurred 2.5 times more frequently. Semenova observed that pneumonia among residents of Zone Z typically followed an unusual, unclear course, often resulting in delayed diagnoses.

Experiments conducted on rats since 1986 have also verified the impact of air pollution on health. The rats exposed to the air of the ‘dirty’ zone for four weeks showed signs of bronchitis, while those remaining in the ‘clean’ zone only exhibited dysfunction of the bronchial tree mucous glands. Confirmation also came from pathologists: the lungs of deceased Zone Z residents contained significantly more dust particles.

In 1988, Semenova made a forecast for the year 2000 based on the level of air pollution and the prevalence of related lung diseases. What she predicted was grim: by the end of the century, the level of air pollution in Almaty from dust, nitrogen oxides, and sulfur compounds would increase exponentially, and the number of pneumonia and acute bronchitis cases would triple, while chronic bronchitis would increase by 1.5 times.

In the almost forty years since Semenova wrote about it, Almaty's key problems have not disappeared: ‘The city is located in an aerodynamic shadow created by the horseshoe-shaped mountain ranges from the southwest and southeast. Therefore, the winds in the city are weak, and there are many completely windless days. Ground inversions persist for long periods of time, and high air humidity contributes to fog formation, leading to smog—the formation of suspended particles of pollutants.’

In 1988, Semenova pointed out that the levels of dust particles, nitrogen oxides, sulfur dioxide, and carbon monoxide were much higher than what was considered safe. Sometimes, they were 10, 15, or even 18 times higher than the maximum allowed levels. Cars (of which there were only a few thousand in Almaty at the time) caused 60–70 per cent of the air pollution, and 30–40 per cent was due to the work of industrial enterprises and power plants.

The situation has not improved since that time.

The mountain system in the vicinity of the metropolis of Almaty still exists, and the weather remains the same, as do the sources of pollution. There are now about 630,000 cars in the city (a number that is increasing by about 70,000 per year), and two thermal power plants still burn coal, as do many—more than 10,000—stoves in private houses throughout the city. This scenario appears almost custom-made for smog formation, generating a photochemical smog reminiscent of Los Angeles in the summer mixed with a blend of London fog in winter. The city frequently experiences a heavy layer of smog, evident when going up into the mountains, such as the Shymbulak tract, where one can observe the dense grayish-purple haze enveloping the city.

Measurements confirm that the air in Almaty is often far from healthy. For example, in January 2024, according to Kazhydromet data, the number of instances of exceeding the maximum allowable concentration (MAC) for various pollutants was staggering: the carbon monoxide level was exceeded more than 1,700 times, the same for nitrogen dioxide, more than 1,500 times for ozone, 500 times for PM2.5 particles, and about 50 times for PM10. Ecologists emphasize that these are the maximum permissible concentrations adopted in Kazakhstan, and these standards are significantly more liberal than WHO recommendations.

Scientists’ observations indicate that during the cold season, the concentration of PM2.5 exceeds the limit of 0.035 milligrams per cubic meter almost every day. This suggests the intensive burning of solid fuels in power plants and the stoves in private households. Additionally, even indoors, the concentration of PM2.5 surpasses the norm. This factor alone leads to the premature deaths of hundreds of people. ‘We conducted calculations through monitoring and discovered how many people die prematurely solely due to particulate matter, without considering other pollutants. In Almaty, it's 2,300 people per year, and in Astana, it's 750 people,’ says Dr Nasiba Baymatova, head of the Biosphere Ecology Laboratory at the Al-Farabi Kazakh National University.

For many years, Dr Baymatova and other activists, ecologists, and scientists have been striving to find a solution to Almaty's smog problem, resorting sometimes to almost guerrilla methods. These are very similar to those of the activist known by the pseudonym Pavel Alexandrov, who began posting data from his air quality sensor on the internet in 2017, and later created an entire alternative network for monitoring air quality, which often proved more accurate than the government's. Four years ago, Kazhydromet reached an agreement with Alexandrov to start incorporating data from his stations into its monitoring system.

The Kazakh authorities have been implementing pollution control programs since Soviet times. In her dissertation, Raisa Semenova mentions the resolutions of the Central Committee of the Communist Party of Kazakhstan and the Council of Ministers, titled ‘On Additional Measures to Prevent Air Pollution in the City of Almaty’, adopted as early as 1985, and similar resolutions in 1989. Air purification programs were also adopted in the late 1990s—for example, one such program involved converting urban thermal power plants into gas plants in 2005. The launch of a new gas-fired thermal power plant is planned for 2026.

If we examine the details closely, it becomes evident that the situation is even more concerning. ‘Thermal power plants (TPP) 2 and 3 burn nearly 3.5 million tons of coal per year, mostly Ekibastuz coal, known for its high ash content—about 42 per cent of it consists of impurities, including sulfur and iron compounds. They use wet scrubbers for emissions control, which are ineffective against PM2.5 particles, and they don't utilize technologies for capturing nitrogen oxide and sulfur dioxide,’ says Baymatova.

In addition to these TPP emissions, we must consider emissions from burning another 1 million tons of coal in private homes. Moreover, Almaty is the most motorized region in the country. Half a million vehicles use non-compliant fuel, and a third of them were manufactured more than twenty years ago, which means they inherently fail to meet ecological requirements.

Despite the complexity of the pollution situation in Almaty, there is cause for optimism. We know what actions can be taken, and they are entirely feasible. Like Dr Semmelweis, who, in the mid-nineteenth century, reduced maternal mortality sevenfold by insisting that midwives wash their hands thoroughly with chlorine water, converting TPPs in Almaty into gas plants will immediately eliminate a significant portion of pollution.

However, if TPPs and household heating switch to gas and if automotive transport meets Euro 4 standards, will the problems vanish? Inversions and fog in cold weather won't disappear, nor will the mountain range on the outskirts of Almaty. The primary source of emissions—automotive transport—will persist. A complete transition to electric vehicles will take decades, and it's uncertain if this technology will prove viable either. Perhaps we have more effective means in our arsenal to tackle air pollution without halting vehicular traffic.

New Delhi, much like many other densely populated regions in India, grapples with exceedingly high levels of air pollution. Smog often compels authorities to shut schools, limit vehicular movement, and even prohibit fireworks during festivals. In order to combat the problem of pollution, city authorities have opted to employ the technology of artificial rain—a method used in Russia to clear the skies over Moscow on 9 May, Victory Day. Essentially, this involves introducing finely dispersed dust into the clouds, typically using silver iodide particles. These particles serve as condensation nuclei, accelerating the formation of larger water droplets and hastening rainfall. Scientists posit that such raindrops can help clean the atmosphere by washing away and binding PM2.5 and PM10 particles, thus stopping dust from ascending into the atmosphere.

In November 2023, Delhi city authorities obtained official permission to implement this method of making it rain. Sachchida Nand Tripathi from the Indian Institute of Technology Kanpur told Bloomberg, ‘Intense rain can enhance the effectiveness of the atmospheric cleansing process.’ However, for this method to be employed, there must, at the very least, be clouds present. Critics of this approach argue that the relief it provides is too expensive, especially for how short-lived it is. Moreover, environmentalists emphasize that such private experiments amount to far less than a well-coordinated policy to reduce pollution.

Following the example set by India in Delhi, Pakistan adopted this approach, although neither country was the first to do so. China had implemented it during the 2008 Olympics in Beijing, although it was used as a complement to a significantly more successful strategy: shutting down industrial enterprises across northern China and removing over 2 million cars from the streets.

Artificial rain is a costly affair. For instance, Moscow authorities allocated over 450 million rubles for this purpose, known as cloud seeding, which employs the same technology. Therefore, in India, they sometimes resort to cheaper means (albeit with a localized effect)—smog guns.

These powerful fans mounted on trucks release fine water mist into the air, up to 100 liters per minute. The resulting droplets, like raindrops, are intended to absorb and capture dust particles. Indian authorities mandate equipping construction sites with such guns, requiring at least one for every 5,000 square meters.

You'd be wrong if you thought that no one ever considered filtering urban air, much like a gas mask does. For example, in 2018, a group of Indian scientists developed the Smog Free Tower project, which was aimed at purifying the air of microparticles using electric fields. In the same year, an air purification tower appeared in China.

A 100-meter tower, erected in the city of Xi'an, habitually plagued by automobile smog, required no energy to operate. At its base, a greenhouse-like platform heated the air, which was then drawn up into the tower, where it passed through filters for purification. Perhaps the builders of the Chinese tower were inspired by a project undertaken by Dutch artist Daan Roosegaarde.

In 2016, he erected a small tower to purify the air in Beijing and synthesized diamonds from the carbon collected.

However, scientists from Krakow have been the ones to take the most extreme approach to tackling the smog issue. They proposed detonating, quite literally, the atmospheric inversion to restore normal air movement (convection), thus preventing the formation of smog. In an article published in the journal Frontiers in Environmental Science, they detailed a series of experiments involving explosions of a gas-air mixture conducted near Krakow. The shockwave from a series of eleven explosions could affect the atmospheric inversion over an area of approximately 4 square kilometers, reducing the concentration of microparticles by 24 per cent.

In 2013, when the Chinese authorities declared their war on air pollution, the residents of Beijing almost never saw blue skies—everything was shrouded in a yellow haze of smog. Ten years later, the pollution level had dropped by 42 per cent, increasing life expectancy by 2.2 years. However unconventional our methods may seem in the fight for clean air, these additional years justify our efforts. We'll certainly find ways to make the most of them—perhaps by simply enjoying the blue sky.

In general, the energy systems of Central Asian countries were established during the Soviet era and need significant modernization, even without taking the issue of emissions and pollution into account. Old boilers and generators are highly inefficient by modern standards, with a substantial portion of energy being lost. In addition, the pipelines and heating systems have aged, resulting in considerable heat loss.

Currently, TPPs operate on low-quality coal, which, as major purchasers, they receive at a substantial discount. This, in turn, helps keep tariffs relatively low for the residents of those areas. However, transitioning to gas, even if not at the population's expense, will lead to increases in tariffs. In addition, gasifying private homes is a challenging task. Currently, many areas of the city are formally gasified, but the reality often looks like this: a gas pipeline is extended to the property boundary, but the expenses of the gas equipment and connection must be borne by the homeowner. These are significant expenses, coming up to around 1 million tenge. Thus, many may find it simpler to buy half a ton of coal for the winter. Many urban residents follow this line of reasoning—they are less concerned about air pollution than about the necessity of staying warm and cooking during the winter.

In 2023, the Development Bank of Kazakhstan, the Asian Development Bank, and the European Bank for Reconstruction and Development (EBRD) allocated funding for a project to transition one of Almaty's thermal power plants (TPP 2) to gas. This transition is anticipated to be completed by 2026. The reconstruction of TPP 3 is also expected to be finished at the same time.

Read the first part of the global history of smog.