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The pollution readings for the air quality map, or air pollution map as it can also be referred to, are shown in the form of US AQI readings, which stands for the air quality index, with the US part indicating that it follows the air quality classification measures used in the United States, which are far more stringent than other measurement systems used throughout the world. As such, pollution readings that other systems may use could be classified as being safer, when in reality they may be a cause for concern, particularly amongst vulnerable groups. To cite some readings taken from mid-June of 2022, US AQI readings of 50 were taken in the center of Kolkata. This reading placed that particular area on the air quality map just within the 'good' rating bracket, which requires a reading of 50 or less for classification (with the closest to 0 being the most optimal).
Other readings went up much higher, with 77, 86 and 99 all being recorded, placing them into the 'moderate' rating bracket, and the figure of 99 being very close to moving up to the higher rating of 'unhealthy for sensitive groups'. These are some examples of pollution readings taken midway through the year, and due to being constantly updated, users should check the air quality map for constant updates, particularly during times when the pollution levels rise to any significant degree.
The air quality map for Kolkata gives readings in the form of the US AQI figure, which is based on the aggregation of several main pollutants that are typically found throughout the world, hence the prevalence of their use in calculating the air pollution level. These pollutants are nitrogen dioxide, sulfur dioxide, carbon monoxide, ozone, and PM10 and PM2.5, the two main forms of particle-based pollution. The latter of the two is far more dangerous, and although outright concentration levels are not shown on the air quality map for Kolkata when the US AQI reading is high and moves beyond the 'moderate' rating bracket, inhabitants of such areas will likely be in much higher contact with ultrafine particles and the aforementioned chemical compounds. As such, this can serve as information for users as to what pollutants they may be breathing when the air quality map readings are higher in Kolkata.
Whilst all inhabitants of Kolkata can benefit from referring to the air pollution map, certain members of society may benefit more. Those whose health is at risk are more likely to benefit from keeping up with current pollution levels, and as such, those with pre-existing health conditions, compromised immune systems, the elderly, young children and babies, as well as pregnant women, call all benefit from referring to the readings shown on the air quality map above for the city of Kolkata.
Whilst some of the factors that lend themselves to higher air pollution levels in Kolkata have been touched on briefly in the article over the various parts of how the air quality map works, and what its readings consist of, a few more of the main polluting sources will be discussed. This is again for educational purposes so that users can better understand the readings that they see for the air quality map above, as well as what is causing higher US AQI readings in Kolkata, which also pertains to many other cities throughout India, with many of them having similar root causes.
With the country of India itself having one of the largest population numbers in the world, which will only be on the rise, there is naturally a tendency towards having higher amounts of air pollution present whenever there are large groups of people. Indian cities can have large populations, as well as many people traveling in and out of the city, with the transportation industry also contributing to rising pollution levels. Wherever there are large amounts of people there will be some forms of pollution being given off as a result, particularly when it comes to movement. This refers to polluting sources such as cars, motorbikes, and fumes given off by heavier freight vehicles such as lorries, trucks and buses, which can raise ambient, year-round pollution readings on the air quality map for Kolkata. The ambient pollution level refers to that which stays consistent throughout the year due to sources that continue to emit particles, chemical compounds and smoke. Fumes from vehicle exhaust contain many of the chemical compounds used in the US AQI readings, along with many forms of particulate matter, which also raises the US AQI level further due to particle-based pollution being a significant component of air pollution levels, as seen above on the air quality map, as well as on the city page for Kolkata, which shows the pollution levels as an average, rather than as individual areas throughout the city. Whilst combustion inside vehicle engines is a significant contributor to higher pollution levels, vehicles can also contribute in other ways (although older and poorer quality cars, motorbikes and lorries will often give out far more noxious fumes and particles than newer models do, due to the poor combustion process taking place in the engine, leading to improper combustion of fuels. This can release materials such as black carbon and volatile organic compounds (VOCs) in higher quantities, as well as older engines also being more likely to release oil vapors). The other ways that vehicles can contribute to higher air pollution readings on the pollution map above is from less well-known aspects such as the residual wear and tear of tire treads causing many tons of microscopic rubber particles to enter the air (as well as settling on the earth or in bodies of water, leading to these particles potentially entering the food chain and making its way to people, and also causing damage to the environment).
Other causes of higher pollution levels and thus higher US AQI readings present on the air quality maps for Kolkata include ones such as poorly paved roads (which can emit large amounts of finely ground particles, particularly when many cars are driving over it daily), emissions from power plants and factories, and any potential open burning of rubbish or organic material, which whilst it is less common nowadays, can still occur, particularly in lower-income areas, not to mention natural combustion sources such as wildfires or similar natural disasters. As the population grows, so too will vehicle ownership, which is on the rise throughout the world and is a growing contributor to worldwide pollution levels, and can be particularly prominent in cities that see large amounts of traffic hemmed into smaller roads and in between buildings, often seen during rush hour periods. All of the above-mentioned issues represent a large part of what makes up pollution spikes on the air quality maps for Kolkata, with a few others also contributing beyond what was mentioned.