Air Pollution 101
Air Pollution is bad, hurts health, but how exactly, with what exposure, and why? Air consists of nitrogen, oxygen, argon, carbon dioxide and small amounts of other gases. When certain constituents of “small amounts of other gases” reach high levels and begin to cause a detrimental effect on human health and the broader environment, they become air pollutants.
This spike can be caused by natural activities like dust-storms or volcanic eruptions, but in the present Age of the Anthropocene, the root cause is typically, human activity. From thermal power plants, industries, vehicles, to waste burning sites, construction, our society and economy is filled with numerous pollution sources around us, which spew a poisonous concoction of gases.
These gases have an adverse effect on both the human body (respiratory ailments such as asthma, chronic obstructive pulmonary disease) and the broader environment (rising temperatures, changes in native plants and animals).
Air pollution is generally caused by the presence of Nitric Oxides, Sulphur Dioxide, Carbon Monoxide, Ammonia, Ozone, Lead and particulate matter (sized 2.5 and 10 micrometers). It is generally measured by an Air Quality Index (AQI), which combines concentrations and levels of various pollutants into a single composite number. It follows a very simple template, the higher the AQI, the worse the air quality.
Particulate Matter (PM1, PM2.5 and PM10)
Particulate matter refers to solid particles or liquid droplets which get mixed in the air. The number added after PM refers to the size of the particulate matter in micrometers. It is important to understand the size of particulate matter as it determines how they are transported by air as well as how far they can enter the airways of our respiratory system. Some particulate matter is visible to the naked eye because of its size.
An easy way to explain this, would be to compare the number of times you have observed dust in the air(which comes under PM10) but none of the others, such as sulphates or nitrates in the air (which are finer particles and come in the PM2.5 bracket).
- PM10: PM10 primarily consists of naturally occurring particles such as dust which are generally visible to the human eye. PM10 levels in the air is also influenced by human activity such as vehicular movement and construction, which throw up more dust and increase the amount of dust circulating in the air. They are particles that can enter our respiratory system and harm us, but can also be easily protected against, due to their bigger size.
- PM2.5: PM2.5 particles are finer particles which as you may have guessed by now, are 2.5 micrometers or smaller. According to Urban Emissions “more than 95% of emissions from diesel, petrol, and natural gas combustion, open waste burning pollution, biomass burning pollution, and coal combustion at cookstoves and boilers, falls under PM2.5.”
They occur mainly through combustion, whether it is burning of petrol/diesel in your car, burning trash outside your house or burning coal to power your factory. PM2.5 is especially deadly due to its ability to mix with other organic compounds in the air (such as nitrates or sulfates) to form more harmful pollutants. The finer PM2.5 particles can travel deeper into your respiratory system and even enter your bloodstream, leading to severe diseases such as chronic obstructive pulmonary disease and cancer.
Nitrogen Oxides (NOx)
Nitrogen Oxide is produced through combustion either in vehicles or industries such as power plants, brick kilns, etc.
NOx in air can directly react and combine with the oxygen in the air, and then begin to linger on. It is important to note that the release of nitrogen in the air is a natural phenomenon, as nitrogen oxides are also naturally generated through microbial processes in the soil. However, human activity pushed these levels to unheard-of levels, which played a part in making nitrogen oxides harmful to us. Nitrogen Oxides are also highly reactive as it can combine with sulphur dioxides (SO2), particulate matter and ozone in the air to form even more dangerous pollutants.
Sulphur Dioxide (SO2)
99% of sulfur dioxide in the air is generated by humans. Main sources are the Industries that engage in processing sulfur-containing material like the burning of coal or processing mineral ores, and vehicular emissions.
Sulphur dioxide is highly toxic to the human body as it immediately irritates the areas of the body which air passes through, i.e nose, throat, and lungs. Thereby even short exposure to SOx leads to high damage, triggers coughing or wheezing fits, and can be especially severe for people already suffering from respiratory diseases such as asthma.
Ozone
Wait a second… Ozone!?! Isn’t that good for us? Turns out, ozone is like your last toxic relationship, the further away it was from you, the better it became for you.
“Good ozone” is the one that you find in the stratosphere, whereas when ozone reaches the ground-level, it becomes “bad ozone”. Ozone at the ground level is not only the main ingredient of “smog”, but it is also harmful and toxic to people and the environment. Ground-level ozone does not naturally occur but is created by chemical reactions between nitrogen oxides (NOx) and other pollutants in the air.
