Bengaluru has cleanest air among big cities, but can it last?

As other parts of the country struggle to deal with smog and pollution, especially during winter, Bengaluru continues to have the cleanest air among metros. However, it remains far from good, slowly inching towards unhealthy levels. 

Bengaluru has maintained a steadily moderate level of air quality over the years. Its AQI has largely remained in ‘satisfactory’ or ‘moderate’ category. 

As per national standards, an AQI in the range of 0-50 is considered ‘good,’ 51-100 is ‘satisfactory’, while 101-200 and 201-300 fall in ‘moderate’ and ‘poor’ ranges, respectively. Anything beyond that falls in the range of ‘very poor’ and ‘severe’. 

However, despite Bengaluru’s steady AQI record, air quality in the city appears to be falling. 

Citizens, especially in East Bengaluru, have raised caution about worsening air quality in winter months. While some blamed illegal garbage burning, others pointed to growing number of vehicles on the road as well as increased construction. 

As per data from the Karnataka State Pollution Control Board (KSPCB) website, AQI at Kadubeesanahalli peaked at 181 at 4 pm on Saturday.

Around the same time, AQI levels across six more locations were over 100, including BTM Layout, Jayanagar, Hebbal, Peenya (Shivapura), Silk Board and Mailasandra. 

The KSPCB has 11 air quality monitoring stations across the city and the Central Pollution Control Board (CPCB) has three. Silk Board Junction saw the second highest AQI at 127, while Jigani saw the lowest at 48. AQI of Bapujinagar was not available due to insufficient data. 

Bengaluru’s day-to-day air quality is shaped mainly by local emissions and meteorological conditions, with the biggest influences coming from traffic congestion, domestic fuel use, construction activity and regional pollution transported from surrounding districts, says Palak Balyan, research lead, Climate Trends. 

“Rush-hour traffic peaks in the morning and evening consistently raise PM2.5 and NO2 levels, while construction dust and on-road resuspension add to PM10 throughout the day, especially in dry months. According to source studies for Bengaluru (by TERI), domestic emissions and transport are dominant contributors, while regional boundary-layer transport adds nearly 18% to daily particulate levels. As a result, PM2.5 is the pollutant that most often pushes city’s AQI to the moderate or poor category, followed by PM10 and NO2 during heavy traffic periods,” she elaborated. 

What’s helping city’s air quality? 

Overall, the city’s air quality remains satisfactory, said a KSPCB official.

“Of the 11 monitoring stations, most are in good or satisfactory range. We see only three locations where AQI peaks to moderate range — Hebbal, Mysuru Road (Kavika), and Silk Board Junction. There are no major points of concern,” he said, adding that even in problematic areas, the AQI does not remain consistently high. 

“There are traffic-prone areas, so sometimes air quality depletes due to high vehicular movement. But even if there’s a spike in AQI, it needs to last for at least two days, for it to be considered poor air quality,” he elaborated. 

The KSPCB has 44 action plans in place to improve the city’s air quality — this includes everything from banning two-stroke vehicles to regularly removing dust and silt from major roads. To understand the source of growing pollution, 44 action plans are being reevaluated and revised based on newer study reports, Eshwar Khandre, Minister of Forest, Ecology and Environment, told DH. 

“Over the last decade, the city has benefited from early adoption of cleaner transport norms transition to BS-VI fuels, expansion of CNG usage in public fleets and introduction of a large electric bus network under BMTC. Bengaluru also moved faster on vehicle-emission testing and phasing out older commercial and diesel autos, which helped control traffic-related PM2.5 and NO2 peaks,” said Palak, adding that large-scale road infrastructure projects  like widening of key corridors, flyovers, and signal-free stretches have helped reduce idling emissions on several major routes. 

But overall, weather remains the biggest factor in maintaining the city’s air quality. 

“This is largely because of its unique environmental and geographical advantages, despite rapid urban growth. The city sits at an elevation of about 900 metres, which naturally promotes better dispersion of pollutants compared to low-lying metros. Its moderate climate with frequent winds, relatively high atmospheric mixing and absence of extreme winter inversion events prevents pollutants from accumulating near the surface for long durations,” added Palak. 

The city also benefits from one of the longest monsoon seasons. Plus, Bengaluru does not experience severe winter inversion like North India. 

Inside the air monitoring station at Veterinary College in Hebbal on Saturday. DH Photos/B K Janardhan

An anti-smog gun installed outside the Vidhana Soudha. DH FILE PHOTO

Cut-off box - Can AQI be tampered with?  
Researchers believe that while India’s air quality measuring standards are already subpar compared to European standards existing AQI monitoring stations do not paint an accurate picture even by those standards. 
A researcher working with the state government believes monitoring stations need to be more widespread to get accurate representation. 
“If you notice most monitoring stations are placed in relatively clean and green neighbourhoods and extra care is taken to ensure that the area around it remains clean and free of smoke and garbage. How will this provide an average for the locality? To get an accurate picture AQI must be monitored for the entire locality. Measure it in the residential area school main road and even the mall and then take an average. That’ll be more accurate” he said. 
When DH visited the air quality monitoring station in Hebbal monitors for various components were neatly stacked on top of each other inside a tiny room. This room is located on the campus of the veterinary college a lush chunk of land surrounded by greenery.