Delhi is one of the most polluted cities in the country and is once again engulfed with dense smog recording PM2.5 599 (µgm-3) per cubic meters and PM10 955 (µgm-3) per cubic meters on 8th November 2017 which comes in the category of severe and is more than ten times the safe level. The pollution in Delhi is a growing emergency and could reach dangerous levels if measures are not taken to curb it.

Q 1 What is the safe limit for pollution in the city?

The safe limit of pollution is -
PM2.560 micro grams per cubic meter
PM10100 micro grams per cubic meter

(PM means Particulate Matter)

Q 2 What do you understand by PM2.5 and PM10?

PM2.5 is affected by the gas emanating from the vehicles.
PM10 is affected by the dust emerging from the construction of buildings and other sources.

Q 3 How do you define the Air Quality index?

The Air Quality Index has six categories - 

  • Good
  • Satisfactory
  • Moderate
  • Poor
  • Very Poor
  • Severe
Q 4 What is the PM10 Index in various cities across India?

The PM10 Index in various cities is- 

  1. Allahabad-250
  2. Ghaziabad-242
  3. Alwar-240
  4. Barreilly-239
  5. Delhi-217
  6. Moradabad-201
  7. Kanpur-201
  8. Faridabad-199
  9. Amritsar-190
Q 5 What does air quality measure?


The air quality measures eight pollutants - 

  1. PM10 
  2. PM2.5
  3. NO2
  4. SO2
  5. CO
  6. O3
  7. NH3 
  8. Pb
Q 6 What are Delhi’s pollution nodes?

The air quality data reveals that Delhi’d pollution nodes are busy depots, heavy traffic, unpaved roads, landfill sites and industries. 

Q 7 Which areas in Delhi head the pollution list?

ITO, Anand Vihar, R. K. Puram and Punjabi Bagh head the pollution list and government is struggling to find solution to address the plight of these areas. 

Q 8 What are the main reasons attributed to pollution in Delhi?

Few of the reasons which lead to increased pollution in Delhi are-

  1. Ever growing population of Delhi
  2. Construction of houses at the cost of Green Patches.
  3. Unstoppable construction activities in the city both by Public Works Department as well as individuals
  4. Industries operating in the city
  5. Burning of garbage
  6. Large number of vehicles on the roads of Delhi
  7. Climate of Delhi is another factor as on a normal day the air flow in Delhi is 1 metre per second. But in order to end air pollution the speed of air should be 6-10 metre  per second                        
  8. Garbage is dumped haphazardly and burnt indiscriminately. 
  9. Public roads are used for parking causing congestion. 
  10. Burning of stubble is also an important factor. 

All this combined together has led to increase in pollution nodes around Delhi and neighbouring areas.

Q 9 What all gets accounted as a reason for high pollution level in Delhi especially during winters?

As per the study carried out by Indian Institute of Technology (IIT) Kanpur - 2015, in Delhi 38 percent of air pollution accounts for the dust arising from the roads and 20 percent is due to gas emanating from the vehicles. Yet another, is gas emanating from the industries and lastly due to the construction work. The air pollution is not restricted to Delhi but the air quality of Delhi in winters is particularly influenced by -

  • Calm weather
  • Very low Wind Speed
  • Low temperature
  • Wind Direction
  • Humidity Solar Index
  • Reduced mixing height

Fog and smog are two separate environmental phenomena and winter has a role to contribute in its increase. All this prevents dispersion of pollutants and leads to their accumulation. 

Q 10 What is the system of measuring the pollution level?


SAFAR-System of Air Quality and Weather Forecasting and Research The air quality in Delhi is monitored by the Central Pollution Control Board (CPCB) and Delhi Pollution Control Board (DPCC). These three agencies collect the data from 28 locations. DPCC monitors two hotspots -

  •    At the airport runway to ascertain the aviation impact
  • Anand Vihar to see the impact of other states and vehicular pollution