Mumbai tops Indian cities in road traffic CO₂ emissions per km: Study

The study found a clear correlation between traffic density and per-kilometre CO₂ emissions.

Mumbai recorded both the highest vehicle density and the highest CO₂ emissions per km of road among the cities analysed.

Other cities, including Chennai, Bengaluru, Pune and Chandigarh, were also classified in a high-density, high-emissions category, though their emission levels were significantly lower than Mumbai’s. Delhi ranked in the mid-high range for per-kilometre emissions, while Guwahati, Indore and Jaipur showed comparatively lower traffic density and emissions.

While Mumbai topped per-kilometre emissions, Delhi and Bengaluru joined it as the three largest contributors to total road traffic CO₂ emissions nationwide. The study, however, noted that per capita emissions from road transport were largely uniform across the cities studied, remaining below 0.2 tonnes of CO₂ per person annually.

Beyond CO₂, the study identified nitrogen oxides (NOx) and carbon monoxide (CO) as the dominant pollutants emitted by road transport across all cities.

Larger metropolitan areas, including Mumbai, Delhi, Bengaluru, Chennai, Hyderabad and Pune, recorded significantly higher levels of these pollutants compared to smaller cities such as Guwahati, Mangaluru and Tiruppur.

In addition to road transport, emissions from residential areas, power generation, heavy industry, MSMEs and aviation are also being estimated. The data will be made accessible through a public web portal and city-specific dashboards for use by urban civic bodies.

The study has been accepted for publication in Scientific Data, a Nature portfolio journal.