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NATIONAL AIR QUALITY INDEX
Aug 22, 2015

In an attempt to make air quality measurement easier to understand, the ministry of environment and forests launched a National Air Quality Index (AQI) . It will put out real time data about level of pollutant in the air and inform people about possible impacts on health.

Government have added five more components to the new measurement process: Particulate Matter 2.5, ozone, carbon monoxide, ammonia and lead

The index classifies air quality simply as good, satisfactory, moderately polluted, poor, very poor, and severe. Each band is represented by a colour code to visually express the level of severity that people can grasp easily.


NATIONAL AIR QUALITY INDEX

Key fact

⇒ The index will cover Delhi, Agra, Kanpur, Lucknow, Varanasi, Faridabad, Ahmedabad, Chennai, Bengaluru and Hyderabad. The index will be later expanded to 46 more cities having a population of more than one million, besides 20 state capitals
⇒ Eight pollutant have been taken into account to calculate AQI

  • Nitrogen oxide

  • Sulpher dioxide

  • PM2.5

  • PM 10

  • Ozone

  • Carbon monoxide

  • Ammonia

  • Lead

⇒ There are six AQI categories, namely Good, Satisfactory, Moderately polluted, Poor, Very Poor, and Severe.  

 AQI

 Associated Health Impacts

Good
(0–50)

 Minimal Impact

Satisfactory
(51–100)

 May cause minor breathing discomfort to sensitive people.

Moderately polluted
(101–200) 

 May cause breathing discomfort to people with lung disease such as asthma, and discomfort to people with heart disease, children and older adults.

Poor
(201–300) 

 May cause breathing discomfort to people on prolonged exposure, and discomfort to people with heart disease

Very Poor
(301–400) 

 May cause respiratory illness to the people on prolonged exposure. Effect may be more pronounced in people with lung and heart diseases.

Severe
(401-500) 

 May cause respiratory impact even on healthy people, and serious health impacts on people with lung/heart disease. The health impacts may be experienced even during light physical activity.

 

⇒ The AQI has been developed by the Central Pollution Control Board in consultation with IIT-Kanpur and an expert group comprising medical, air-quality professionals and other stakeholders

 

 

Additional Information (Particulate matter)

 

They are Also known as particle pollution or PM, is a complex mixture of extremely small particles and liquid droplets. Particle pollution is made up of a number of components, including acids (such as nitrates and sulfates), organic chemicals, metals, and soil or dust particles.

They can come in almost any shape or size, and can be solid particles or liquid droplets. We divide particles into two major groups. These groups differ in many ways. One of the differences is size, we call the bigger particles PM10 and we call the smaller particles PM2.5. 

BIG. The big particles are between 2.5 and 10 micrometers (from about 25 to 100 times thinner than a human hair). These particles are called PM10 (we say "P M ten", which stands for Particulate Matter up to 10 micrometers in size). These particles cause less severe health effects.

SMALL. The small particles are smaller than 2.5 micrometers (100 times thinner than a human hair). These particles are called PM2.5 (we say "P M two point five", as in Particulate Matter up to 2.5 micrometers in size). 

 

Coarse Particles (PM10) 

Fine Particles (PM2.5) 

What they are

  • smoke, dirt and dust from factories, farming, and roads

  • mold, spores, and pollen

  • toxic organic compounds

  • heavy metals 

How they’re made

  • crushing and grinding rocks and soil

  • then blown by wind

  • driving automobiles

  • burning plants (brush fires and forest fires or yard waste)

  • smelting (purifying) and processing metals

 

Particulate Matter and India

The PM2.5 is particularly dangerous and can cause adverse health effects owing to its greater penetrability into the human respiratory system and eventual accumulation in human organs and blood. Rural women, children and elderly population are more prone to diseases caused by air pollution. Rural women, in particular, face a greater risk from indoor pollution — locally made mud stoves fuelled by solid biofuel emit a far greater amount of finer particulate matter.

Air quality of any area depends on local emissions, long-range transport, local and regional weather patterns, and to some extent the topography of the region. Due to increased buoyancy and efficient ventilation in summer, pollution plumes rise effortlessly to the free atmosphere. This leads to a reduced level of surface level PM2.5 concentration in our breathing zone. The problem gets aggravated during winter. Adverse conditions during winter help trapping of pollution leading to elevated level of surface PM concentration.

Compared with peninsular India and coastal regions, the situation is far worse in the Gangetic Basin, especially during winter months. The Himalayas act as a barrier to dissipation of pollution plumes emanating from the cities located in the Basin. As a result, cities in the Basin are more prone to sustained bad air quality.

The National Air Quality index, has created greater awareness of air pollution amongst the but mo concrete action needs to be taken


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