Describe the key points of the revised Global Air Quality Guidelines (AQGs) recently released by the World Health Organisation (WHO). How are these different from its last update in 2005? What changes in India’s National Clean Air Programme are required to achieve these revised standards? (150 words) [2021]

The World Health Organization (WHO) has released revised guidelines for air quality, known as the Global Air Quality Guidelines (AQGs). These guidelines provide recommended levels of air quality to protect the health of populations by reducing the levels of key air pollutants as follows.

The annual average for PM2.5 should not exceed 5 micrograms per cubic meter of air, while the 24-hour average should not exceed 15 micrograms per cubic meter.
The annual average for PM10 should not exceed 15 micrograms per cubic meter of air, while the 24-hour average should not exceed 45 micrograms per cubic meter.
The ozone levels should not exceed 100 micrograms per cubic meter over a 24-hour period, and the nitrogen dioxide levels should not exceed 25 micrograms per cubic meter over a 24-hour period.
The sulfur dioxide levels should not exceed 40 micrograms per cubic meter over a 24-hour period,
The carbon monoxide levels should not exceed 4 micrograms per cubic meter over a 24-hour period.

These guidelines are a revision of the previous guidelines released by the WHO in 2005.

In India, the National Clean Air Programme (NCAP) has been launched to address air pollution in 122 cities by targeting a 20-30% reduction in PM10 and PM2.5 concentrations by 2024, compared to 2017 levels. To achieve the revised air quality standards set by the WHO’s Global Air Quality Guidelines (AQGs), India may need to implement the following changes in NCAP: