“NEW DELHI: Not just extreme heat, air pollution levels are also peaking in many parts of the city. Even ozone (O3) levels are beginning to cross the safe standard — PM2.5 concentrations are already nearly twice the safe limit at most locations.
While the winter smog is visible to the naked eye, high O3 levels may be an indicator that concentrations of invisible gaseous pollutants like oxides of nitrogen (NOx) may be very high at many locations” Times of India
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