At first glance, the concern about air pollution, smog or pollution in cities has been relegated to the background by universal and more alarming issues, which monopolize more centimeter in the media, such as global warming, climate change, the recent Amazon fire, the active hurricane season, the melting of the world's glaciers, the melting of Arctic and Antarctic ice, or the danger that seals of permafrost break and release huge amounts of CO2 into the atmosphere, stored for millions of years under the soils of these extensive natural coal sinks.
There are hundreds of millions of people who live surrounded by shoddy airs in countless cities, many more than most believe. For the men, women and children who live in these big smoke cities, who suffer from severe and almost permanent smog, the problem is part of their daily life. For them smog has a character closer and more urgent than climate change and other dangers on the planet, more distant and abstract than dense smoke, that which prevents visibility a few meters from their faces, that which they must breathe and swallow. on the way to their jobs and schools, despite the mask they are wearing.
People's concern about smog, we corroborate it directly, through the tools at hand. With them we can measure the issues that most concern people. Every day we realize that the calamity of poor air quality, far from passing into the background, for many has been increasing and is becoming a fundamental issue.
Origin of the word smog
Smog is derived from the English "smog," which in turn comes from the combination of "smoke" and "fog," smoke and mist, respectively.
Causes of air pollution
Since the end of World War II, we have witnessed the expansion of megacities, industrial zones, power plants and nuclear plants that spit out puffs of smoke from their chimneys. Tens of millions of motor vehicles of all kinds circulate through the streets and highways of these mega-cities, releasing enormous volumes of gases through their exhaust systems. To this must be added dust, pollen, mold spores and other solid particles from fires and other sources.
The combination of air with these pollutants during a prolonged period of high atmospheric pressures (anticyclone), causes stagnation of the air and, therefore, the permanence of them in the troposphere (closest layer of the atmosphere to the ground, of about 12 kilometers high) due to its higher density. There are two types of smog: industrial and photochemical. The first is related to factories and the second to automotive traffic.
The problem of smog is aggravated in some cities, such as Madrid, for example, as the Spanish capital lacks natural corridors whose winds could expel stale air in a short time. A similar phenomenon occurs in Los Angeles, Mexico City and in many other cities in the world that have high levels of smog.
The opposite happens in Caracas, due to the geographical characteristics of the privileged valley where the city sits, full of trees where the eye is directed. The capital of Venezuela, located 900 m above sea level, two or three times a year the haze or haze is formed, a mist loaded with small particles of dust, ash, clay or sand in suspension. Another type of haze occurs due to smoke from distant fires. In both cases the mist disappears in a short time, when the wind begins to blow, purifying the city air again, as is its natural characteristic.
Formation and composition of air pollution
Part of these polluting fogs are parked on the cities acquiring different shades, between gray, brown or red. Most of the smog we observe is photochemical smog, produced by the reaction of sunlight with nitrogen oxides and one or more volatile organic compounds in the atmosphere. Nitrogen oxides come from exhaust gases from cars, coal-fired power plants, and emissions from factories. Volatile organic compounds are released from gasoline, paints, and cleaning solvents. When sunlight hits these chemicals, particles form in the air, which we call smog.
Main components of smog and the diseases they can cause
Nitrogen oxides, both nitrogen monoxide (NO) and nitrogen dioxide (NO2) are two colorless, non-flammable, highly toxic gases and the main pollutants present in smog. They come mostly from the exhaust of motor vehicles that use fossil fuels, but also from the smoke of industrial areas. Both NO and NO2 are the greatest threats to health in large cities. They are related to the formation of mucus from the airways, a condition that can increase the risks of contracting chronic diseases such as allergies and asthma. Nitrogen oxides are very irritating and in high concentrations can cause bronchitis and pneumonia.
Ozone, as well as protecting us from the dangers of ultraviolet radiation from the sun in the upper parts of the atmosphere, when it is close to the ground is harmful to health. Ozone that is produced in a non-natural way originates from other products, especially nitrogen oxides, aided by the intensity of sunlight, which is considered a secondary pollutant. Ozone causes irritation of the mucosa and lung tissues, irritation of the eyes, expectoration, migraines and chest pain. Prolonged exposure to ozone causes major damage such as cataracts, blindness, skin cancer and effects on the immune system.
Sulfur dioxide is an irritant to the respiratory tract. In high concentrations it produces bronchitis and tracheitis. It can also aggravate respiratory and cardiovascular diseases.
Airborne particles can worsen asthma, respiratory and cardiovascular disease. Chronic exposure to high concentrations increases the risk of death.
Lead can cause learning delay and behavior disturbances.
Carbon monoxide, in high concentrations, disables the transport of oxygen to the cells. Prolonged exposure can cause dizziness, headache, nausea, states of unconsciousness and even death.
Benzene produces harmful effects on the bone marrow. It damages the immune system and is associated with the development of myeloid leukemia. In women, this compound can cause irregularities in the womb and pass from the blood of the mother to the fetus if they are pregnant.
Some countries with the worst air quality in the world
- Africa: Nigeria, South Africa and Tunisia. Asia: India, Pakistan and China. Europe: FYR Macedonia, Bosnia-Herzegovina and Poland. North and Central America America: Mexico, the United States and Jamaica. South America: Peru, Chile and Brazil.
How to solve or mitigate the problem of air pollution?
There are different levels of actions that we can carry out, both with our personal contribution and with the intervention of local or national authorities, especially in the most polluted or poorer quality cities. At the first level we consider palliative measures, but more practical and quick to implement, although their effectiveness is considerably less than that of the second level.
The Twenergy site, an online community, which aims to "serve as a reference in the field of energy efficiency and sustainable development", recommends:
“Install catalysts in the exhaust pipes of vehicles. Improve the quality of public transport service that reduces the number of vehicles on the roads. Reduce travel needs by encouraging videoconferences and directing urban designs towards proximity. Restrict access to motor vehicles in city centers. Replace the use of the car with other less polluting modes of transport such as the train, or even, if possible, the bicycle. Improve combustion in power plants. Substitute components that use VOCs (paints, solvents…) with others that do not contain them or avoid evaporation as much as possible. Promote the generation of electricity through renewable energy. ”
The second level is the most effective, although more complex to achieve. This is the Paris Agreement, which aims to achieve the goal of zero fossil fuels by 2050. Before this, there are intermediate goals to reduce greenhouse gas emissions and their consequences, the smog among them. To shut down the last internal combustion engine, all vehicles using fossil fuels must have been replaced by electric cars. If this is achieved, the dream of cities with silent and decarbonised cars, free of contamination, is fulfilled. Also the generation of conventional electrical energy will have to be replaced by wind energy, solar energy and other clean sources to produce electricity. It is also worth mentioning the adaptation of current cities to green cities,with extensive areas of parks and gardens with a predominance of trees.
