Winter fog in Indian capital a toxic cocktail of pollutants: Govt study
The hazardous quality of air in India's capital New Delhi and the National Capital Range (NCR) surrounding it, received a gloomy stamp of approval from a new government study. An analysis by India's Ministry of Earth Sciences for the period between 2016 and 2021 found that episodes of fog in Delhi have ceased to be natural occurrences.
This is because they no more comprise of suspended water droplets. Instead they comprise of a toxic cocktail of nitrates, magnesium and fluoride compounds.
According to the study, the episodes of fog studied in the five-year period were found to be comprised of a significant share of chlorides, sulphates and nitrates, and ions of calcium and ammonium.
These constituents are all the by-products of vehicular emissions and construction activities.
"Natural fog is white in colour but in the northwest India region, the colour of the fog changes depending on the dominant pollutant in that region. For instance, in Delhi, the colour of the fog is generally grey because of the high vehicular emission in this region. If you go to areas with high number of industries or areas where burning activities are rampant, the colour of the fog will be black," a senior official of the Ministry of Earth Sciences, was quoted as saying by Hindustan Times.
What does the study mean for residents?
For residents of Delhi and National Capital Range (NCR), it simply means that being outdoors in winter is dangerous. The study approves credible scientific apprehensions about health crisis among general population stemming from hazardous air quality during winters.
What all does smog in Delhi-NCR comprise of?
The analysis for the period between 2016 and 2021 found chlorides comprised the highest share of fog (24 per cent), followed by calcium ions (23 per cent), ammonium ions (15 per cent) and nitrates (14 per cent). Other pollutants that were found in the Capital’s fog over the five-year period were sulphates (14 per cent), magnesium ions (4 per cent), sodium ions (3 per cent), potassium (2 per cent) and fluorides (1 per cent).
Studies from the past have shown that in the 1990s, Delhi’s fog was white in colour, thicker and would take longer to disperse, as is in the case of natural fog. In past decade, this has changed to the point that fog is now grey with an acidic composition.
Delhi's 24-hour average Air Quality Index (AQI) stood at 357 on Monday, worsening from 259 on Sunday.
An AQI between 201 and 300 is considered 'poor', 301 and 400 'very poor', and 401 and 500 'severe'.