Over billions of years, meteorological and geological processes such as meteorite impacts, volcanic eruptions, and ultraviolet radiation have shaped the Earth's atmosphere, influencing life on the planet. Changes in the atmosphere, such as the increase in oxygen during the Proterozoic era, have caused species extinctions and the emergence of new forms of life. Since prehistoric times, the use of fire has generated atmospheric pollutants. The introduction of coal in the XIII century contributed to widespread air pollution, with detrimental effects on human health, exacerbated during the industrial revolution of the XVIII and XIX centuries.
Until the late 1950s and 1960s, air pollution was not considered a major concern, but rather a localized issue in industrialized urban areas. However, following the significant environmental disasters of the last century, public opinion and political agendas underwent a radical transformation, recognizing pollution as a serious and urgent threat. Three significant episodes in the first half of the 20th century played a fundamental role in shifting attitudes and policies.
The first historical event occurred in the Meuse River Valley, Belgium, in December 1930, where a combination of meteorological conditions led to the accumulation of air pollutants, resulting in 63 deaths and over 6,000 cases of intoxication. The second event, in Donora, Pennsylvania, in October 1948, was characterized by dense and persistent fog, causing approximately 20 deaths and a high rate of respiratory illnesses attributed to the widespread use of bituminous coal. The third episode was the Great Smog of London in December 1952, where thermal inversion trapped smoke and pollutants, resulting in the deaths of thousands of people and leading to a national crisis.
The historical events of air pollution shared common factors: industrialized areas with pollutant sources such as coal and unfavorable meteorological conditions. The fatal consequences primarily affected infants and elderly individuals with pre-existing heart and lung conditions. Recognition of the problem and its addressability gradually emerged over time, necessitating scientific data, continuous monitoring, and radical changes in human activities. However, the slowdown in addressing the issue has resulted in global economic consequences and delays in transitioning to clean and sustainable energy sources.
Air pollution, primarily caused by human activities, represents a serious threat to both health and the environment globally. It is responsible for numerous severe diseases, including heart disease, stroke, lung cancer, and diabetes. According to the Institute for Health Metrics and Evaluation, in 2017 it caused approximately 5 million premature deaths worldwide, ranking as the fourth leading risk factor for mortality. Air pollution is a significant global problem, causing health and environmental damages in both developed and developing countries. In China, the issue is particularly alarming, with the Global Burden of Disease estimating that in 2017 alone, pollution caused approximately 1.24 million premature deaths, accounting for a quarter of the global total. However, for a long time, air pollution and its health effects have been underestimated due to a lack of information and inadequate monitoring systems.
Air pollution occurs when the atmosphere contains substances that cause measurable harm to humans, animals, vegetation, or materials, which are typically not present or present at lower levels in the normal composition of the air. These pollutants are mainly of anthropogenic origin, such as gases produced by industries and agriculture. The main atmospheric pollutants include sulfur oxides, nitrogen oxides, carbon monoxide, atmospheric particulate matter, ozone, radon, benzene, and benzo[a]pyrene. Pollution can be either outdoor or indoor, with different impacts.
- Sulfur Oxides (SOx): these include sulfur dioxide (SO2) and sulfur trioxide (SO3), primarily emitted from the combustion of sulfur-containing fuels. They can cause respiratory and cardiovascular damage, as well as being responsible for acid rain.
- Nitrogen Oxides (NOx): this group includes nitric oxide (NO) and nitrogen dioxide (NO2), primarily produced from high-temperature combustion. They have harmful effects on respiratory health and can contribute to the formation of photochemical smog.
- Carbon Monoxide (CO): produced from the incomplete combustion of organic substances, such as vehicle exhaust gases. It is highly toxic, interfering with the transport of oxygen in the blood and causing harmful effects on the cardiovascular and respiratory systems.
- Atmospheric Particulate Matter: composed of solid or liquid particles suspended in the air, it may include dust, soot, and metallic compounds. It can penetrate the respiratory system, causing lung and cardiovascular damage.
- Ozone (O3): present in the stratosphere and partially transported to lower atmospheric layers, it can cause eye and respiratory irritations, as well as cardiovascular and pulmonary problems.
- Radon (Rn): a natural radioactive gas emitted from the soil and buildings, it can increase the risk of lung cancer when inhaled at high concentrations.
- Benzene (C6H6): highly flammable and carcinogenic, it can cause leukemia and bone marrow damage. Long-term exposures can have severe health effects, while short-term exposures to high concentrations can be fatal.
- Benzo[a]pyrene: the main pollutant of the polycyclic aromatic hydrocarbons (PAHs) family, is carcinogenic to humans. Emitted from various sources, including diesel engines and solid fuels, it can induce carcinogenic pathologies upon exposure.
Air pollution is a complex and global issue that requires urgent and concerted action at the international level. While awareness of its harmful effects on health and environment has increased over time, it is crucial to continue monitoring and addressing sources of air pollution by adopting policies and technologies aimed at reducing pollutant emissions and promoting clean and sustainable energy sources. Only through collective and systematic commitment can we protect our atmosphere and ensure a healthier future for generations to come.