6dos% of city enterprises produce, supply or support the production of metal step step three5 . Interestingly, although Novokuznetsk is not a city with coal-oriented economy, coal is actively used as input in its production of metal as conversion of most or all metal ores to usable metal is highly energy intensive. Metal production facilities use coal to provide energy and the metals are being produced by conversion of coal to coke, where both processes emit substantial NO₂ emissions in the atmosphere. ₂ emissions from a previous study 36 . Notably, NO₂ emissions from metal production of West-Siberian Metal Plant (WSMP) account for 84.2% of all the gaseous pollutants of . Most importantly, we found high correlation (r = 0.76) between inventory-based NO₂ emissions from WSMP 36 and our annual NO₂ tropospheric estimates from OMI and, where even higher correlation (r = 0.84) was discerned between WSMP NO2 emissions and coal production from Fig. 4 . These findings clearly indicate that metal manufacturing of Novokuznetsk is based on coke-intensive input, thereby pointing on a key role of coal in these emissions.

Dialogue

The sensitivity of tropospheric NO₂ (measured by OMI) to the mining, production, and transportation of coal in Russia’s largest coal basin (Kuzbass) was demonstrated for the first time. A major long-term tropospheric NO₂ anomaly was revealed over Kuzbass (3.22 ± 0.52 ? 10 15 molecule/cm 2 ) in the period 2005–2018, indicating substantial gaseous pollution over the region. The anomaly was attributed to the Kuzbass coal basin, based on moderate agreement identified between (1) the spatial distributions of NO₂ and night lights originating from the cluster of coal mines and cites, as well as by (2) the correlation between inter-annual coal production and annual NO₂ levels in Kuzbass (r ? 0.60).