Overview

• The CPCB’s affidavit filed on September 25 reviewed ozone data from 178 monitoring stations across 10 metropolitan regions.
• In 2023, eight-hour standards were exceeded at 25 of 57 stations in the National Capital Region, 22 of 45 in the Mumbai region, and 6 of 12 in Pune.
• Short-term spikes and rare nighttime breaches were recorded in Mumbai and Pune, highlighting episodic and diurnal variability.
• The board linked elevated ozone to photochemical reactions from NOx and VOCs driven by transport, power plants and industry, with CO and methane also playing roles.
• For April–July 2024, one-hour exceedances were observed at 21 of 57 NCR stations and none in Mumbai, and researchers are urging targeted controls to limit exceedances.