Delhi has been covered in a deep blanket of smog for the past few days. The AQI of almost all areas has exceeded the danger level. Meanwhile, the question also arises as to why air pollution increases so much in winter that it becomes deadly. This happens not only in India, but in all countries of the world. The Great Smog of London was the first incident that drew attention to this.
The effect of air pollution in London began to become visible since the 19th century, when the administration at that time intermittently prohibited the burning of coal. But the incident that occurred in London in the 20th century became such an incident, after which many countries, including Britain, learned a lesson. This is the case on December 5, when dense darkness began to spread in London during the day and soon all the surrounding areas were affected by it. The people who had gone to the office tried to return home but got lost.
Visibility was so bad that people couldn’t even see their feet. Many people left their cars on the road and started walking. They had been lost due to darkness. Many lives were lost due to the cold, but the greatest loss was due to smog.
People started getting sick due to the smog that lasted for four to five days. Crowds began gathering in front of hospitals with respiratory problems, fever and vomiting. The hospitals were not prepared for this emergency, they began to back down. It is believed that in the same number of days more than twelve thousand deaths occurred due to respiratory problems.
What was the reason for the smog?
In Britain, coal was burned on a large scale to keep houses warm in winter. Factories also ran on coal. This smoke was causing problems but the cause of the Great Smog was much greater. In fact, on December 5, an anticyclone passed over London. This is a weather pattern in which the sky remains clear but when it forms, cold air is trapped below and warm air builds up above. In a way, this is the position of the bottle cap, so the liquid or air underneath remains frozen there. This is what happened in London. To alleviate the cold, coal was burned there, which did not rise and remained trapped at the bottom. This caused the Great Smog.
What changes occurred after this?
Immediately after the incident in the 1950s, the British government passed the Clean Air Act. Under this, the burning of coal in homes and industries was banned. Many other measures were also taken so that the smog incident does not occur again. Exactly ten years later, the same incident occurred again in London. This was also called Great Smog 1962. However, due to the strictness of the government, this time the casualties were limited to a thousand deaths.
Be it London, any other part of the world or Delhi-NCR, the common thing in the case of smog is that it is only visible in winter. Why is it like this? And why is the northern part of the country more conflictive than other regions?
In northern India, pollution increases in the months after the monsoon. There’s a big reason for this: winter inversion. Generally, as we ascend, the air temperature decreases, while in winter the upper air is warmer and the lower air is colder. Because of this, smoke, dust, and other gases remain circulating downward, rather than upward. This effect is visible in the form of smog.
But here’s a question. If this pattern forms everywhere in winter, why is the worst situation only in Delhi-NCR?
In cities located near the sea, such as Mumbai or Kerala, the air and humidity of the sea contribute to the spread of pollution. While the northern plains, which include Punjab, Delhi, Uttar Pradesh, Bihar and West Bengal, are like a valley. Polluted air accumulates here and cannot escape. For this reason, pollution was clearly visible in the form of smog during winter.
Even during summer, vehicles and factories remain the same, but air pollution is reduced. During this time, due to the heat of the sun, the air becomes lighter and rises, so the dust and smoke that accumulates below get plenty of room to rise. The same thing happens in winter too if the day is hot.
