In my previous blog post, we saw that environmental protection enables a better, longer, and healthier life and that it is, therefore, an integral part of public health and a necessity of the 21st century. Now is the time to explain the mechanisms of air pollution in numerous cities around the world.
Just remember whether you were in the cities of Southeast Europe in January and did see the sky? Did you visit Milan in the fall or winter and you could barely breathe? Do you know anyone who lives or have you been to Stuttgart? Have you experienced or seen images of pollution in Mexico City or mega-cities in India or China? Air pollution is found everywhere on the planet, and these cities are just examples of various causes worsening the local situation. World aero- and light pollution (urban night light) has led to the fact that one-third of humanity never sees the Milky Way [1] because the sky is not visible from the ground cocktail of particles and pollutants. We saw the accelerated and temporary disappearance of smog from Asian cities at the beginning of the lockdown last year. Not seeing the sky is hence not a natural state of affairs, but the long-term solution is certainly not for the whole economy to stop.
Serious air pollution is present in two forms – summer and winter smog. Summer smog, the effect of a fata morgana submerged in a light mist and sun rays, typical of Paris or Los Angeles, does not have the same formation mechanisms as winter smog. Winter smog is "older" because this so-called "fog" has been a big problem in cities since the middle of the last century and is associated with the colder part months. To explain the reasons for these effects, I will call on environmental chemistry, and then Cedevita – a well-known powdered instant orange drink in the Balkans.
In short, environmental chemistry answers the question of what happens to matter, how it moves, transforms, accumulates, or how it is dispersed through various chemical processes in water, air, soil, etc… This area and the corresponding legislation introduce the notion of a pollutant as a chemical compound or particle that has an established negative effect on humans and/or nature. The place from which the pollutants come out is called a polluter, and professionally, that leaking is called emission. There is another very important term in this area, and that is immission. This is the value we can see in those air monitoring apps; the value of immission is the current concentration of pollutants in the air because the monitoring devices measure the state of pollution in the ground in real-time, e.g. downtown.
Surprise, surprise! Emission and immission are related. The higher the emission level, the faster the pollutants reach the air, but the final value of a pollutant in the air will be affected by meteorological factors (wind, rain, temperature, air pressure, sunshine), geographical conditions (valley, slope), various physical and chemical processes, etc. To summarize, the emission refers to the pollutant and it can be managed through technological solutions for flue gas purification, but the value of the immission is partly in the hands of higher force. There is legislation for both; its strictness, application, and effectiveness are other issues.
How does air pollution develop? Imagine a simple example of making an orange drink from Cedevita or another instant powder-based drink (go back to being a kid and imagine your favorite alternative). If you put (i.e. emit) 1 spoon full of instant powder (i.e. pollutants from polluter) in a glass of water (i.e air), ordinary water will, after a while become orange drink (i.e air will go from unpolluted to polluted). The juice will first be bright orange at the bottom (i.e. contaminated on the ground) and transparent at the top. If you add another spoonful of powder, the same thing will happen again, only the final color of the juice will be stronger (i.e. the air will become more and more polluted). The value of immission in this case is proportional to the color of the drink at the bottom - the more polluted the air, the more orange it is. Hence:
spoon = polluter
Cedevita powder = pollutant
the amount of Cedevita per spoon = emission value
making the drink = emission
juice color at the bottom = immission value
Clearly, I just asked you not to mix the drink even though it’s your reflex before you drink it. To drink it without mixing, you have two options: 1) to add water to dilute it further and wait for a very long time for the color to even out in the full glass, or 2) you will not drink such a "layered" drink at all. But you can’t add air to the city (option 1 is out of the question) nor can you choose not to breathe (option 2 is biologically impossible). In this case, we, therefore, talked about the conditions of calm and cold weather when there is no wind or rain when you can expect very polluted air near the ground.
With a little luck, it may start raining or the wind blowing, that is, someone can mix the powder in a glass for you. Here, however, you are limited by the will of another, by some higher force, so this is not the best way to quench your thirst (i.e. to breathe). When the wind "disperses the pollution", there is a dilution effect - the juice becomes uniformly light orange. Rain has a similar effect because it "scrubs" pollution from the air, but it goes into rivers and onto green areas. In any other environmental area like wastewater management, dilution is prohibited by law because everyone would be doing so if it were allowed, but the air is a public good so things get a tiny bit more complicated.
Cedevita has existed since 1929, and air pollution has always existed, the only question is which level does not have a serious or irreversible effect on human health. In essence, what interests public health is the color of the juice at the bottom of the glass, and if it is even one shade too orange relative to what the medical/toxicological studies have established as ok - a public problem arises. Urban air pollution has escalated with a high degree of urbanization and an increase in the quality of life (btw it is good that we live better than our grandparents). Today, more than half of the world's population lives in cities [2]. The increased population density in cities has its economic benefits, but the other side of the coin is that it concentrates the total emissions needed for work, life, and entertainment of residents.
The spoon with which you pour the powder into the water is arbitrary - it has the same emission effect regardless of whether it is large, small, wooden, plastic, metal… In that sense, the world's largest chronic air pollutants are 1) power plants, i.e. electricity production and district heating, especially if they rely on the so-called dirty fossil fuels like coal which is the case around the world; 2) individual fireplaces or boilers for heating; 3) industrial activities and agriculture, by which I mean everything from the production of corn, biscuits to steel and chips; 4) traffic consisting of cars, public and freight transport on diesel or gasoline.
Depending on the degree of economic development, position and relief of the city, season, and even the share and quality of fossil fuels in energy production, the relative contribution & importance of each of these groups of polluters will differ. That is why in industrial cities such as Stuttgart or Milan (both in the valleys), traffic is given great importance [3,4] - houses are mostly heated with clean gas, and power plants and industrial plants have legally required removal of "problematic compounds". In contrast, in Eastern Europe or Asia, where energy is mostly obtained from coal, the relative importance of energy and combustion plants in winter is significantly higher.
Next, air pollution is one big cocktail of diverse components, just not of supplements like Cedevita is. This cocktail depends on the season, but in winter there are active pollutants such as sulfur dioxide (SO2), nitrous oxides (NOx) and soot particles, PM10 (particle less than 10 microns - many times smaller than a human hair), PM2.5 (smaller sister of PM10, less than 2.5 microns). In one way or another, all these substances penetrate the lungs and in case of excessive exposure, cause chronic lung diseases, bronchitis, asthma, and even cancer [5]. The first two also create acid droplets in contact with moisture and fall as acid rain in nature, where they start drying and rotting of greenery. They are emitted by polluters that rely on the combustion process. In summer, volatile organic compounds from diesel emissions are also important, which contribute to the creation of summer smog, and this also has a corrosive and irritating effect on the respiratory organs.
Example of a city whose population doubled in just a few last decades, but whose air quality is still good.📍Lausanne, Switzerland.
So what is to be done? Limit emissions by personal activity and public action and financially encourage green energy transformation of course.
At the level of energy production and energy efficiency, there are several possibilities, of which the overhaul and improvement of thermal power plants with serious waste gas purification systems is the first and basic. The "fuel" change follows; the use of renewable energy sources is an inevitable future, but it also has its problems because such a kilowatt depends on meteorological conditions, and requires serious ore exploitation. In addition, replacing current with higher quality boilers (from coal to pellets, for example) is essential because it reduces the emission of harmful compounds. Improving the energy efficiency of houses with the help of facade insulation is an integral part of this story because it consumes less energy. Some of these measures are long-term, some can have an imapct n a few seasons.
In terms of traffic, public transport should be a priority. A developed transport grid enables people to commute reliably without fuss, unnecessary emissions, and noise. If you can, choose public transportation - not your car. The Bike to Work initiative is popular in May and June - so hop on your bike to the store, to the doctor’s, to meet your friends... It feels good, that's for sure.
Finally, for those who do not have the privilege of clean air (this is an oxymoron), as long as you see high pollution indices, I advise you to reduce your stay outside, not to do sports and demanding physical activities, not open the windows "just to air the room" because nothing good will come in. If you have to stay outside, a scarf or a textile mask over your face can do a lot for you (we have been practicing wearing it properly for more than a year). I am ashamed to tell someone in 2021 that it is best to wear a mask to prevent acid droplets or particles from reaching his lungs. Since these stay on the fabric while you inhale, regular washing without fabric softener will help protect you, as much as possible in your area of immediate impact. Stay out of pollution zones whenever possible, give your lungs a break and a chance to serve you for a long time.
Honestly, consciously and informedly,
Ing. env. dipl. EPF Switzerland
Dipl. inž. zaštite životne sredine, Srbija
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Picture from personal collection.
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