The ADHM – 2017 vs 2018 – Race Stats and Environment Numbers

I choose to run and party in polluted Delhi air, but should you?

How did bringing the 2018 race date forward change the environment and event numbers for New Delhi’s race, the ADHM? The weather was more uncomfortable, and the pollution levels were still very dangerous, and while the women were faster, the men were slower.  Read on for more…

I wrote a few weeks ago, about the tradeoffs between pollution and weather, just prior to New Delhi’s premier recreational distance running race, the Airtel Delhi Half Marathon (ADHM). I had published a paper (here), written an easy guide to it (here) and provided you with a decision tool (here) using New Delhi as a case study, surrounding its public annual open-air event.

Race Date Brought Forward

This year, 2018, the race date had been brought forward into October following public hue and cry about it coinciding with high levels of November air pollution in previous years. We expected it to be warmer at the earlier date this year. But we also expected the pollution levels to be lower because of higher temperatures, and from being much earlier than Diwali, as well as from being near the start rather than the middle of the stubble-burning season.

Uncomfortable Indian weather has a more marked impact on performance i.e. race times. We see slower timings in warmer, more humid weather, especially if there are no winds. Pollution, on the other hand, primarily impacts short, medium and long-term physical and mental health.

[There is a slight negative impact of pollution on race times, but for recreational runners, the typical difference will be unnoticeable.]

I have already reported about the failure rate of the official race pacers here.

This is what I am reporting to you today, section-by-section:

Click to go directly to
Pollution Still Very Dangerous
Participant Numbers
Performance Improvement or Worsening?
Key Policy Takeaways


There was no rainfall on any of the race dates recently, and here are what the temperature, gusts, and humidity have been on the race dates in the last few years. The “Feels Like” is a useful practical measure to also note. Pay closer attention to the years 2017 and 2018 as they are relevant to the race times I discuss below.

ADHM Race Day Temperatures
ADHM Race Day Gusts
ADHM Race Day Humidity
ADHM Race Day Feels Like



As a first stab at pollution levels, we can look at the median levels for each day around the race events. We can centre our viewing window on a choice of one of (i) race date, (ii) Diwali, or even on a (iii) fixed calendar date e.g. 15th October each year.

If we create a window with a view on either side of the race date, we can see that this year, 2018, compared to 2017, had lower levels of pollution on race date, as well as on the days immediately before, and after race date. [As earlier, we can use the US Embassy AQI (Air Quality Index) as a good proxy for pollution levels.]

Centering the Window at the Race Event Date

If we create a window with a view on either side of Diwali, we can see how criminal the polluting of air with celebratory fireworks is. The burning of (crop) stubble by farmers upwind from Delhi exacerbates the situation further. This, along with the calendar year effect can be seen if we centre the window on the 15th of October each year.

Centering the Window at Diwali
Centering the Window at 15th October



Although ADHM-2018 seems to have lower levels of pollution than ADHM-2017, it is important to note that the pollution levels were still very dangerous for human health. Based on the US’s Environmental Protection Agency (EPA) guidelines here we can see the hourly pollution levels for 2 days on either side of the race which was flagged off at 5am on 21st October 2018.


Although the race organizers claim that they had taken measures to clean the air of pollutants, we have quantified proof of no reduction of pollutant levels to anything close to safe.

It is not the responsibility of race organizers to clear pollution from the air. However, publicity that they have been taking measures that are effective conveys the wrong message, and so, is a great disservice to the health (and fitness) of their fee-paying customers.

It would have been better to have taken the anti-pollution actions and measured their effect commencing quite a few days prior to the event and reported on their effectiveness with hard numbers on a daily basis.



The number of finishers (a decent proxy for participants) in the half-marathon has bounced back since the media scare during the 2015 event. It is important to note that registrations (fee income) are typically not affected by the pollution scares. In fact, the event day costs are lower if there are fewer customers who actually dare turn up on race day.

Bounce Back!



In order to examine any improvement or worsening of race times between 2017 and 2018, we must look at those who ran in both years. Fortunately, this is a sizeable proportion of runners. Across both years 4,084 runners finished in both years. This was 44% of all finishers in 2017 and 43% of 2018.

Between genders and across age groups, the finishers common to both races looked like this.

Women/Men across age groups who ran in BOTH years

Examining the improvement in net race times at a very broad level, again separately for genders and across age groups, this is what we see.

First for Females (on avg 75-sec improvement):

areas of bubbles reflect relative numbers of runners


Now for Males (on avg 33-sec slower):

areas of bubbles reflect relative numbers of runners

These are, of course, broad stats, matching each runner’s times with their time the previous year. In an earlier article, I addressed such consecutive pairs for a much larger set of runners across multiple pairs of years here to answer the question “Are Recreational Marathoners in India getting Faster?” In an even more robust analysis, here, I demonstrated that “You Might Run Slower Sooner Than You Think” after attempting to adjust for weather conditions, aging, and elevation, for a group of runners who ran the Mumbai Marathon 7-years in a row.



Race organizers should pay greater attention to the tradeoffs between weather (ticket sales) and pollution (health). This attention should be focused on details and not be driven by brouhaha or media frenzy. The details should focus on execution quality and monitoring of that quality in terms of quantifiable results. Whether or not they take action to reduce the level of pollutants, they should make pollutant levels along the course of the race known to the paying public.

Individual runners should also pay attention to similar tradeoffs when it comes to deciding whether to attend an outdoor event in a polluted city – be it a race or a wedding dance [did you see the title photo? I did both with my Sikh brother in Delhi pollution]. For each individual runner, their daily lifestyle, which might include training for a race, should take into account and benefit from the weather and pollution conditions they are likely to find themselves in.

My own policy decisions? I don’t worry about pollution. I am concerned about it, but I do not worry! My lifestyle choices are planned in detail and executed with care to allow me a long Healthspan, regardless.



Dr Purnendu Nath spends his waking hours focusing on helping individuals and organizations reach their goals, to make the world a better place. He speaks, writes and advises on topics such as finance, investment management, discipline, education, self-improvement, exercise, nutrition, health and fitness, leadership and parenting.


  1. Puru…nice article and thanks for the incisive thought

    But “In fact, the event day costs are lower if there are fewer customers who actually dare turn up on race day.” may not be true…provisioning has to be made for the full count of bibs never know who will not turn up


    • Assuming that at any event the actual turnouts are lower than the expected turnouts then the variable costs associated with turnout numbers will be lower. The fixed costs, I agree, remain the same. Where vendors promise they will take back extra supplies then that definitely turns out to be a saving for the organizer.


  2. Hi Puru,
    Good read and stats! How does the pollution and other weather aspects play out during Mumbai marathon ?


    • Dear Sreenath
      In general, Mumbai has less pollution along its race route thanks to lower pollution overall and a sea-breeze. So, relative to Delhi, less pollution (great) but warmer weather and higher humidity (not so great) along with hills (the Bandra-Worli Sea Link and Peddar Road). Of these, the pollution will have only a marginal impact (almost unnoticeable) in terms of race finish times, and the weather and elevation factors will dominate.


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