The World Health Organisation (WHO) on Wednesday released stringent air quality guidelines, lowering the recommended levels of pollutants that can be considered safe for human health.
While a PM2.5 concentration of 25 micrograms per cubic metre in a 24-hour period was considered safe earlier, the WHO has now said that a concentration of over 15 micrograms is not safe.
The recommended levels of six most common air pollutants — PM2.5, PM10, ozone, nitrogen dioxide, sulphur dioxide , and carbon monoxide – have all been revised downwards from the existing norms that have been in place since 2005.
PM2.5 and PM10 refer to particulate matters of sizes 2.5 microns or less, and 10 microns and less, respectively (micron is one millionth of a metre), and are the most common pollutants, as well as causes of respiratory diseases.
The new guidelines take into account several scientific studies in recent years that have suggested that air pollution is much more damaging to human health than earlier known. By WHO’s own estimates, nearly 7 million deaths every year can now be attributed to diseases that are a direct cause of air pollution.
