Running in Delhi’s Polluted Winters: My Lessons

Winters in Delhi (and most of north India) have been marred by high levels of air pollution over the last few years. While it affects everyone living here, I’ve noticed that many runners either make uninformed decisions or are simply lost due to the lack of meaningful discussion on this topic. This is my third full running season in such conditions, and I would like to share my personal observations, learnings and anecdotal thoughts with the community. This is in no way medical advice, and assumes the absence of any pre-existing health conditions.

Myth 1 - Mornings are best for running

This is a misconception even seasoned runners hold. Sadly, this is not the case and based on the PM 2.5 readings I take throughout the day, the hours before sunrise and after sunset are actually the worst times to be outdoors. The best time is in fact 11 AM - 6 PM, when the readings subside the most.

(Data source - https://www.aqi.in/in/dashboard/india/delhi/new-delhi/pm)

Myth 2 - Pollution is significantly less indoors

This is another common misconception among a lot of people. However, if there aren’t any acute sources like nearby traffic or burning, the difference between outdoor and indoor PM 2.5 levels is often less than 10%. Hence, merely shutting the doors and windows does not guarantee cleaner air.

Myth 3 - You can build immunity against pollution

This one irks me a lot, as many people think that living in these conditions can induce immunity. This is completely false, and constant exposure to high PM 2.5 levels can cause long term health issues. The goal should be to maximise your training while minimising your exposure.

Myth 4 - Accuracy of official AQI readings

This is a controversial take, but I have almost never seen the official readings tally with the ones I take using my device. Most of the time my readings are higher, sometimes they are lower. This shows that pollution levels can vary sharply within even short distances, depending on the micro climate.

Practical Options

Here are some practical options in increasing order of exposure which one can consider:

• Move out (if possible) - This is the best option out of all, if you can afford to move out of the region for a couple of months then there is nothing better. But it is obviously not practical for most people.
• Treadmill with air purifier - Although treadmill running has its own demerits, this is the best option to maintain mileage while minimising exposure. Make sure that the treadmill room has minimal air leaks via doors, windows etc. This is why private treadmills are much better than the ones at public gyms, where the doors open too often for any air purifier to be of use. When selecting an air purifier, make sure that the HEPA filter is at least of H13 grade (H14 is the gold standard). Also, check that the maximum coverage area listed by the manufacturer is at least equal to your room size.
• Run with an N95 mask between 11 AM - 6 PM - If outdoor running is your thing, then this is the best that can be done. If the mask is sealed correctly over the nose the exposure is minimised as much as possible, although it is possible to feel itchiness in the eyes which still remain exposed. If that happens, then it is best to use a hydrating eye drop. If the burning sensation is overwhelming, then don’t continue this option. Also, ensure that you don’t run on roads with traffic/construction/dust. Dedicated sports facilities like athletic tracks would be ideal. Remember that your easy/tempo paces will drop because of the reduced oxygen availability.
• Scientific approach to training - If you can, then get a decent AQI meter (the one on purifiers can be inaccurate) and measure the pollution levels before starting a workout. There are plenty of Chinese manufactured meters available on Amazon (I use this one). The next best alternative would be to check crowdsourced AQI readings from sources like IQAir. If the value is less than what you subjectively deem safe, then perhaps you could run outdoors (reputed sources [1] suggest strictly staying indoors at AQI > 300). A higher value could mean a treadmill workout, and on worst days perhaps ditching running in favour of an indoor bike / weights / mobility would be the best thing to do.

Running through Delhi winters isn’t just about showing up every day, it’s also about knowing when not to. The obsession with streaks and mileage often clouds our judgment, but in an environment like ours, health has to take priority over heroics. As runners, we pride ourselves on resilience, but resilience might mean adapting and choosing cleaner air over the next Strava upload. The roads will still be there when the air clears, and so should we.

Sanchit is a software engineer who started running as a hobby and got addicted. If he’s not running, he’s probably thinking about his next run or surfing Strava. He can be reached out on Twitter @sanchit3008 or on Strava at this URL.