Dear MEL Topic Readers,
Why India caps pollution reading at 500 when the air is far more toxic
Though there is no universal air quality index (AQI), a formula provided
by a Swiss-based air quality technology company, IQAir, is most widely used. It
is based on PM2.5 and other pollutants, using data from its monitoring stations
to calculate a real-time AQI. Examples of the Air Quality Index (AQI) include
different levels like Good (0-50), Moderate (51-100), Unhealthy for Sensitive
Groups (101-150), Unhealthy (151-200), Very Unhealthy (201-300), and Hazardous (301-500).
In November, the air quality in northern India becomes so dusty and ashy that
people can hardly go outside. In fact, apps backed by the government show 500,
the upper limit of India’s air quality index scale, while other monitors like
IQAir’s show much higher numbers. The 500-cap was set based on the assumption
that showing higher figures wouldn’t make a significant difference in health impact.
Also, the Ministry of Earth Sciences wanted to avoid causing panic by showing
higher numbers. Anyway, if the index shows 500, you just want to stay inside
and turn on air purifiers to minimize the impact on your health, and wear a
face mask if you have to go outdoors.
Read the article about India’s air quality index.
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