The latest air-quality guidelines released by the World Health Organization (WHO) show that air pollutants are harmful at much lower levels than previously thought. WHO has recommended minimum air quality standards for six types of hazards. These include particulate matter (PM), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide. Typically, air cleaning efforts measure and focus on particles in two groups: those up to 10 and 2.5 micrometers. They can enter our lungs, and small pieces of them can also enter our bloodstream. The level of exposure considered safe for all pollutants has been reduced. For example, for PM2.5, we should not be exposed to an average of more than 15 micrograms per cubic meter within a 24-hour period, which was less than 25 earlier. For PM10, no more than 45 micrograms, below 50.
The readings of PM2.5 and PM10 levels in urban India reveal how unhealthy the air we breathe. Many cities have been plagued by dangerously high concentrations of these particulates for long periods of time. Ensuring yourself clean air is a matter of supreme urgency. Once smog-laden Beijing managed to clean up big cities. Delhi in particular has a long way to go.
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