Marathoners raise concern over huge discrepancies between official readings and data recorded on personal devices; according to multiple runners, portable air quality monitors sensors used during the run showed AQI levels ranging between 200 and 350 at different stretches of the route
Several runners alleged AQI levels ranged between 200 and 350 at different stretches of the route, according to personal scanners. PIC/ASHISH RAJE
Several runners who took part in the Tata Mumbai Marathon (TMM) on Sunday (January 18) raised concerns over a sharp discrepancy between air quality readings recorded on their personal devices and those reported by the Brihanmumbai Municipal Corporation (BMC), questioning the accuracy of the civic body’s Air Quality Index (AQI) calculation method.
According to multiple runners, portable air quality monitors, smartwatches, and mobile-based sensors used during the run showed AQI levels ranging between 200 and 350 at different stretches of the route — readings classified as “poor” to “very poor” as per Central Pollution Control Board (CPCB) standards. In contrast, data displayed on BMC-operated monitoring stations indicated AQI levels largely in the “satisfactory” to “moderate” range, around 80-100, as per CPCB standards.
Runners on the Coastal Road as smog blankets the sky. PIC/ASHISH RAJE
“My AQI monitor showed levels as high as 236 when I was in the holding area of the Full Marathon, and levels fluctuated between 382 and 465 when I was passing through the holding area of the Half Marathon. However, the BMC monitors have shown levels as low as between 80 and 100. How can there be such a huge difference? Even if we consider that various monitors use different parameters, the difference in levels cannot be this huge. Post marathon, two of my friends have been constantly coughing,” said Aneesh Bhasin, one of the runners who ran the 42 km (Full Marathon) and flagged this issue.
Another runner who also raised concerns was Girish Mallya, who has run in all 21 editions of the event. Mallya told mid-day, “The organisers, in the advisory, ideally should have mentioned the expected AQI levels and weather conditions.” Participants said the difference was particularly worrying given the physical exertion involved in long-distance running. “When you are running for hours, breathing deeply, air quality matters a lot. Seeing such high numbers on our devices while official data suggested relatively clean air is confusing and concerning,” added Mallya.
AQI level displayed on a personal device. PIC/BY SPECIAL ARRANGEMENT
Runners have alleged that there may be gaps in how AQI is calculated or represented by civic sensors and Maharashtra Pollution Control Board (MPCB) scanners, including the placement of monitoring stations, averaging methods, or time lags in data reporting. Some also pointed out that on-ground conditions, such as traffic congestion near certain stretches, construction activity, and weather factors, may not be adequately reflected in official readings.
Organisers respond
“AQI levels are transient and keep changing from place of place, and it might not be accurate information for us to give. Mumbai, like all major metropolitan centres, faces its own urban challenges, and our focus remained on what was firmly within our operational control. We worked closely with civic authorities to implement targeted measures during the event window, including intensive road cleaning, dust suppression through mist blowers and water sprinkling, real-time environmental monitoring, and early-morning race scheduling to optimise conditions for runners. This year, the Mumbai Police had also facilitated a coastal route that offers an added natural advantage, with the early-morning sea breeze supporting air movement during race hours and contributing to more comfortable running conditions,” said Neha Kandalgaonkar, vice-president, corporate communications, Procam International.
BMC clarifies
“The private monitors used by these athletes aren’t authentic and cannot be relied upon. Also, they consider the air quality only of a particular area they are in. However, monitors that we use take into account the ambient air quality and ambient atmosphere. Our monitors use the certified parameters of PM2.5, PM10, sulfur dioxide (SO2), carbon monoxide (CO), and nitrogen dioxide (NO2). A third-party expert in the field manages all 23 monitors that have been collectively put up by the BMC, MPCB and IIT-Bombay across the city,” said Additional Municipal Commissioner Avinash Dhakne, who is also in charge of the environment.
Expert Speak
Manoj Kumar from the Centre for Research on Energy and Clean Air (CREA), said, “One can experience easier breathing when inside an office space. But walking in the middle of a traffic jam, one may smell pungent gases that come from the combustion of vehicle engines. When there is physical exercise, one needs to inhale a lot. So the experience is very different in comparison to when in a resting position. That is the reason they are experiencing difficulty in breathing.”
How does India calculate AQI?
Eight major pollutants are taken into account: particulate matter (PM10 and PM2.5), carbon monoxide (CO), ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2), ammonia (NH3), and lead (Pb). To calculate AQI, data for a minimum of three pollutants must be present, of which one should be either PM10 or PM2.5.
AQI vs NAAQS
Air Quality Index (AQI) is the reading seen on pollution level monitors each day. Each country has its own accepted formulae for calculating AQI. The National Ambient Air Quality Standards (NAAQS) readings are a result of what is the accepted norm regarding pollutant levels in ambient air, as per any country. According to NAAQS, India has accepted 60µg/m³. As per the World Health Organisation (WHO), acceptable levels of PM2.5 are an annual average of 5 µg/m³, with a 24-hour average of 15 µg/m³. Experts say there is a need to consider the sub-index values. “In the US, air quality isn’t considered good with pollutants between 0 and 12 µg/m³, while in India, it is acceptable up to 30 µg/m³. In US standards, our AQI may be in the poor category, but in India, it is satisfactory or good quality. In India, unlike other countries, the acceptable NAAQS is very lenient, given our resilience,” Manoj Kumar, from CREA, said.
Possible reasons for discrepancies
BMC monitors are stationary: There are 23 such monitors across the city, located in selected areas with a mix of residential demography, traffic congestion, commercial areas such as bakeries, and industrial units
Different from marathons: Runners on city roads calculate AQI in real time, at any given location. Personal monitors show higher readings because they capture vehicular movement, wind patterns, and industry emissions from areas nearby.
Numbers game
Air quality as per SAMEER App
on Sunday (January 18) AQI level Main pollutant
MPCB monitor, Colaba 64 PM10
Navy Nagar, Colaba 92 PM10
Kherwadi, Bandra East 101 PM10
Subscribe today by clicking the link and stay updated with the latest news!" Click here!
