How Rain Brings Down AQI and Science Behind It
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| AI Generated |
We all love the smell of rain, don’t we? But beyond the earthy fragrance and cool breeze, rain plays a big role in cleaning the air we breathe. The connection between rainfall and AQI (Air Quality Index) is quite direct rain acts like nature’s own air purifier.
When it rains, water droplets in the air trap dust, smoke, and other pollutants, pulling them down to the ground. This process, called “wet deposition” helps clear out harmful particles like PM2.5 and PM10 that float around and make the air unhealthy. As a result, the AQI drops, and the air becomes fresher and safer to breathe.
A Real example from Guwahati
On 13th June 2025, before the rain, the AQI in areas like Ambikagiri Nagar and Railway Colony was around 86 - 87, which falls under the “Moderate” category. After the rain on 14th June, the AQI dropped to around 44 - 49, moving into the “Good” range. That’s a clear sign of how rain can instantly improve air quality.
Science behind how rain brings down AQI
When it rains, the falling water droplets act like tiny vacuum cleaners for the atmosphere. As these droplets descend, they collide with and capture airborne pollutants like dust, soot, pollen, and harmful particulate matter such as PM2.5 and PM10. This process is known as wet deposition or precipitation scavenging.
Here’s how it works:
- Coagulation: Raindrops attract and bind with tiny aerosol particles as they fall. These particles stick to the droplet’s surface and are carried down to the ground.
- Washout effect: Pollutants suspended in the air are literally washed out by the rain, leading to a noticeable drop in AQI (Air Quality Index).
- Rain intensity matters: Heavier and longer rainfall is more effective at cleaning the air. Light drizzles may not have the same impact.
So next time it rains, take a deep breath it’s not just the weather changing, it’s the air getting a little kinder to your lungs.
However, it’s worth noting that while rain is great at removing solid particles, it’s less effective at clearing out gaseous pollutants like nitrogen oxides or ozone. Also, once the rain stops, pollutants can return if their sources like traffic or industry remain active.
So, next time you see those dark clouds rolling in, know that they’re not just bringing relief from the heat they’re also giving your lungs a little break.
Worried About Health in this pollution? Get a Air Purifier now.
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