Delhi AQI Live: The air quality in Delhi is barely improving, while Hyderabad enjoys good air at 87. Delhi faces higher AQI levels because of the combination of vehicular pollution and stagnant winter air. Roughly, Hyderabad also sees 5 million vehicles daily. But what separates the two cities is Ventilation Indices (the ability of the atmosphere to disperse pollutants) and altitude. While Delhi lies in a low-lying river basin, Hyderabad sits at an average elevation above sea level on the Deccan Plateau. On February 14, when Hyderabad recorded air quality in two digits, Delhi recorded the AQI of 202.

The main reason Delhi is recording an AQI of 202 is a weather condition called thermal inversion.

In February, cold air flows down from the Himalayan region and spreads across the Indo-Gangetic plains. Cold air is heavier than warm air. It settles near the ground and acts like a lid over the city. This lid traps smoke from vehicles, factories and burning waste close to people’s breathing level. As a result, pollution builds up day after day instead of dispersing.

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Contrary to that, Hyderabad maintains a higher Ventilation Index even as winter ends. It is because the city is situated on the Deccan Plateau and it is also close to the coast. This setting provides a better vertical air movement, meaning that air pollutants could rise and mix with cleaner air above. As a result, Hyderabad AQI comfortably remains below 100.

Wind plays a big role in cleaning the air.

In Delhi, surface winds are very weak at present, moving at only about 5 to 10 kilometres per hour. This creates a stagnant zone where pollution from the entire NCR area stays trapped and keeps increasing each day.

Hyderabad, on the other hand, is getting steady easterly winds. Even though the city has around five million vehicles on the road every day, the wind helps push polluted air away before it can build up to dangerous levels. In simple terms, the wind is acting like a natural broom.

The type of pollution in the two cities is also very different.

PM 2.5 causes air pollution in Delhi. Every year, when the winter air is already heavy, the pollutants from burning fuel trap in the air. Since these particles are two small in size, they easily enter our lungs when we breathe.

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