Does Stubble Burning Cause Delhi's Smog?
Every winter, Delhi's air turns toxic and stubble burning gets much of the blame. The truth is more complicated, and any company writing about it should say so.
How much does stubble burning contribute?
Estimates vary a lot. NASA-linked researchers describe a range of roughly 10 to 50 percent of Delhi's pollution, depending on the day and the study. On peak days it can climb above 40 percent. Averaged over a season it is closer to 20 to 30 percent. One 2019 estimate said up to 44 percent of PM2.5 on a single November day, and a field study found about 14 percent.
What has changed?
Fires have dropped sharply. Government figures show around 90 percent fewer stubble fires across Punjab and Haryana in 2025 compared with 2022. Punjab recorded 71,304 fires in 2021 and only around 5,000 to 11,000 in the two most recent seasons.
But did Delhi's air get cleaner?
Not as much as you would expect. A December 2025 analysis by the Centre for Science and Environment found that the weeks after burning ended were worse than the burning weeks. The worst day of the season, with an air quality index of 461, came on 14 December, after the fires had stopped.
What does that tell us?
Stubble burning matters, but it is not the whole story. Vehicles, construction dust, industry and winter weather, such as still air and low temperatures that trap pollution, all play a part. Stopping stubble fires will not fix Delhi's air on its own.
Where does a board maker fit in?
Using straw for boards creates a paid use for a material that is often burned. That helps farmers and may reduce burning in a small way. But we do not claim that BIOMEBOARD™ solves Delhi's smog. It would be untrue. Also note that our board is made from wheat straw, while the autumn smog is mainly linked to paddy straw.
How to read a smog statistic
- Check the year and the day. Peak days look very different from season averages.
- Check whether it is a share of PM2.5 or of all pollution.
- Check who did the measurement and how.
- Be careful with a single number. The honest range is wide.
FAQs
What causes Delhi's smog in winter?
A mix of vehicle exhaust, dust, industry, burning of waste and crop fires, trapped by cold, still air.
Is stubble burning the main cause?
Sometimes the largest single source on peak days, but not always. Studies disagree.
Has stubble burning gone down?
Yes, sharply, according to government data.
Can straw boards help clean the air?
They give straw a use other than burning. That can help, but it is not a full fix.
What can I do?
Support cleaner transport, reduce dust and choose products that use waste responsibly.
Did Delhi's air improve when fires fell?
Not clearly. The worst day of last winter came after the fires had ended, which shows other sources matter too.
Want to see how we use straw? Visit our materials page.