The effects on human health due to poor air quality mainly involve the respiratory system and the cardiovascular system. Individual reactions to air pollution depend on the type of pollutant a person is exposed to, the degree of exposure, the individual's health and genetics.
Indoor air pollution and poor urban air quality are listed as two of the worst toxic pollution problems in the world in the 2008 report. Outdoor air pollution causes 2.1 to 4.21 million deaths every year. Overall, air pollution causes the deaths of approximately 7 million people worldwide each year and is the single largest environmental health risk in the world.
Given the great variety of substances present in the atmosphere, numerous classification methods have been proposed: firstly it can be classified according to the chemical composition, for which we mainly speak of compounds that contain sulfur, compounds that contain nitrogen, which contain carbon and halogen compounds.
Secondly, it can be classified according to the physical state: gaseous, liquid or solid; finally, it can be divided according to the degree of reactivity in the atmosphere, into primary or secondary substances. According to the WHO, particulate pollution is responsible for the reduction of 1 year of life on average.
The pathologies that show a significantly higher risk are those affecting the cardiovascular and respiratory systems, including lung tumors. The negative effects of carbon monoxide on human health are related to the ability of CO to join blood hemoglobin to form carboxyhemoglobin (COHb).
In this way the CO occupies the place normally occupied by oxygen, so as to reduce the ability of the blood to transport oxygen and consequently the amount of oxygen that the blood leaves in the tissues. Furthermore, there is the possibility that CO joins with some compounds present in the tissues themselves, reducing their ability to absorb and use oxygen.
The concentration of COHb present in the blood is naturally linked to the concentration of CO present in the air that is breathed. There are many studies done to understand the link between the percentage of COHb in the blood and the macroscopic health effects.
The damage caused by COHb to human health is essentially linked to the effects on the cardiovascular system and the nervous system. The worst short-term civilian pollution crisis in the world was the 1984 Bhopal disaster in India.
The leaked industrial vapors reveal that at least 3,787 people have died and 150,000 to 600,000 injured. The UK suffered its worst air pollution event when the Great Smog of 4 December 1952 formed over London. More than 4,000 died in six days, and more recent estimates have brought the figure to nearly 12,000.
An accidental leak of anthrax spores from a biological warfare laboratory in the former Soviet Union in 1979 near Sverdlovsk is believed to have caused at least 64 deaths. The worst single air pollution incident in the United States occurred in Donora, Pennsylvania due to emissions from a zinc-producing factory in late October 1948, when 20 people died and over 7,000 were injured.