Table 1. WHO air quality guidelines (WHO, 2021) short time averaging pollutant thresholds.

Pollutant	Averaging time	Air quality guidelines
NO ${}_2$ [ug/m ${}^3$]	1-h	200
SO ${}_2$ [ug/m ${}^3$]	10-min	500
CO [mg/m ${}^3$]	8-h	10
	1-h	35
	15-min	100