Exactly How Much Does Diwali Harm Delhi’s Air?

News reports this year suggested that people are now more aware that fireworks increase Diwali air pollution in Delhi, and there were reports of reduced sales of fireworks. But with 22 million people, Diwali must go on. So that got me to thinking: just how much does Diwali pollute our air?

To get to the bottom of it, I stationed our trusty Dylos DC1700 particle counter on my porch.


Diwali firecracker air pollution PM2.5


I tracked (outdoor) Diwali air pollution before, during, and after the festival in Green Park, New Delhi. Here’s what I found:


Diwali Pollution Graph 2015

The left axis is PM2.5 (ug/m3) and the colors represent the AQI. I also plotted the WHO limit, Beijing’s 2015 average, and Delhi’s average to put things in perspective.



Delhi winter air averages 220 micrograms/m3, but during the peak Diwali fireworks on November 11, our numbers spiked to almost 700 micrograms/m3! That’s a heart-stopping 28 times the WHO 24-hour limit of 25 ug/m3.

By comparison, Beijing’s air is often criticized, but Delhi peaked at about 7 times the Beijing average.

I always look forward to Diwali, but I’ll be packing a pollution mask!

Mask fit test India N95


Nerd note: I converted the Dylos 0.5 and 2.5 micron counts to approximate PM 2.5 ug/m3 using the semi-official formula.

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