Measuring Air Pollution
On the basis of how the air pollution impacts human health, certain standards for Air pollution have been set. Such standards are often set only for the Ambient air, i.e. the air surrounding us in the outdoors.
WHO establishes Global Air Quality Guidelines (AQG) based on scientific evidence of health risks. It sets limits for pollutants like PM₂.₅, PM₁₀, NO₂, SO₂, CO, O₃, and lead.
The guidelines aim to minimize health risks, especially for vulnerable populations. WHO regularly updates standards based on new epidemiological and toxicological data. It provides interim targets for countries struggling to meet stricter limits.
National Ambient Air Quality Standards (NAAQS) Guidelines
NAAQS considers WHO guidelines, local air pollution trends, and public health studies to create its own standards in India.
These standards are set by the Central Pollution Control Board (CPCB) under the Air (Prevention and Control of Pollution) Act, 1981. These guidelines were introduced by CPCB in 2009.
- It defines safe limits for industrial, residential, and ecologically sensitive areas.
- It includes pollutants like PM₁₀, PM₂.₅, SO₂, NO₂, O₃, CO, Pb, NH₃, benzene, arsenic, and nickel.
- Limits are enforced through air monitoring networks, industrial regulations, and pollution control measures.
Key Difference between NAAQS and WHO guidelines
- WHO standards focus on global health-based thresholds.
- NAAQS adapts standards to India’s environmental and economic conditions while aiming for WHO compliance.
Guidelines on Air Pollution:
The NAAQS guidelines for SO2, NO2, PM10, PM2.5, O3, Pb, CO, NH3, Benzene, Benzo Pyrene (BaP), Arsenic & Nickel are as follows:
| Time Weighted Average | Industrial, Residential, Rural, and Other Areas (µg/m³ or mg/m³) | Ecologically Sensitive Area (Notified by Central Government) (µg/m³ or mg/m³) | |
| Particulate matter
(< 10 µm) or PM10 |
Annual | 60 | 60 |
| 24 hours | 100 | 100 | |
| 24 hours | 60 | 60 | |
| Sulphur dioxide (SO₂) | Annual | 50 | 20 |
| 24 hours | 80 | 80 | |
| Nitrogen dioxide (NO₂) | Annual | 40 | 30 |
| 24 hours | 80 | 80 | |
| Ozone (O₃) | 8 hours | 100 | 100 |
| 1 hour | 180 | 180 | |
| Lead (Pb) | Annual | 0.5 | 0.5 |
| 24 hours | 1 | 1 | |
| Carbon monoxide (CO) | 8 hours | 2 | 2 |
| 1 hour | 4 | 4 | |
| Ammonia (NH₃) | Annual | 100 | 100 |
| 24 hours | 400 | 400 | |
| Benzene (C₆H₆) | Annual | 5 | 5 |
| Benzo(α)Pyrene (BaP) – particulate phase only | Annual | 1 | 1 |
| Arsenic (As) | Annual | 6 | 6 |
| Nickel (Ni) | Annual | 20 | 20 |
Change in Standards for the Particulate Matter
WHO changed the standards for the Particulate matter in 2021. PM2.5 guideline values were set at 10 μg/m3 annual mean; and 25 μg/m3 24-hour mean; Now these have been updated. Similarly a few other standards have been updated too:
| Figures in g/m³ | WHO (2005) | WHO (updated) | India (NAAQS) |
| PM2.5 annual mean | 10 | 5 | 40 |
| PM2.5 24-hour mean | 25 | 15 | 60 |
| PM10 annual mean | 20 | 15 | 60 |
| PM10 24-hour mean | 50 | 45 | 100 |
| Ozone (O₃) annual mean | – | – | 60 |
| Ozone (O₃) peak (8-hour mean) | 100 | 100 | 180 |
| Nitrogen Dioxide (NO₂) annual mean | 40 | 10 | – |
| Nitrogen Dioxide (NO₂) 24-hour mean | – | 25 | – |
| Sulfur Dioxide (SO₂) 24-hour mean | 20 | 40 | – |
| Carbon Monoxide (CO) 24-hour mean | – | 4 | – |
NAAQS sets fixed limits for pollutants, but it does not tell about the level of production and its intensity.
Therefore, National Air Quality Index (AQI) simplifies pollution data into color-coded categories for public awareness. AQI provides real-time updates, helping citizens take immediate precautions, whereas NAAQS is regulatory and long-term. AQI also reflects health impacts, making it more actionable for individuals.
‘National Air Quality Index’ (AQI)
MoEFCC aims to create ‘One Number- One Colour-One Description’ for the common man to judge the air quality within his vicinity. It is the continuation of the initiatives under the Swachh Bharat Mission to ensure the Culture of cleanliness.
- CPCB along with SPCBs has been operating the National Air Monitoring Program (NAMP) covering 240 cities in the country. In addition, continuous monitoring systems that provide data on a near real-time basis are also installed in a few cities.
- Easy to understand: No voluminous data. Information on air quality is put up in the public domain in simple linguistic terms.
AQI Scheme:
An Expert Group comprising medical professionals, air quality experts, academia, advocacy groups, and SPCBs was constituted and a technical study was awarded to IIT Kanpur.
- Six AQI categories: Good, Satisfactory, Moderately polluted, Poor, Very Poor, and Severe.
- Total 8 parameters: The current measurement index had been made quite comprehensive with 5 additional parameters (PM10, PM2.5, NO2, SO2, CO, O3, NH3, and Pb) for which short–term National Ambient Air Quality Standards (up to 24-hourly averaging period) are prescribed.
- Sub-Index: For example, Calculated for each pollutant, Based on the measured ambient concentrations, corresponding standards and likely health impact. The worst sub-index reflects overall AQI.
- Associated likely health impacts for different AQI categories and pollutants have also been suggested, with primary inputs from the medical expert members of the group.
- The AQI values and corresponding ambient concentrations (health breakpoints) as well as associated likely health impacts for the identified eight pollutants are as follows:
System of Air Quality, Weather Forecasting and Research (SAFAR) Index
Introduced by M/o Earth Sciences (MoES) for greater metropolitan cities of India: Delhi, Pune, Mumbai & Ahmedabad.
- It is developed by IITM, Pune & operationalized by IMD.
- [Indian institute of Tropical Meteorology.]
- Objective: to increase awareness among general public regarding the air quality to provide location specific information on air quality in near real time.
- If 5% of people suffering from air-pollution related diseases take advantage of the advisories & precautions in Delhi alone, it would result in saving of nearly ₹2,500 Cr in terms of health-related cost benefits.
- It is based on AQI on a particular day. It is a part of Air Quality Early Warning System operational in Delhi and will strengthen the existing network of SAFAR, CPCB & SPCBs.
- Health advisory and related precaution will be notified to prepare citizens well in advance.
- It will also provide measurement of online automatic ultrafine particles PM1 and Mercury in addition to other indicators.
INDAIR
- CSIR-NEERI has launched the country’s first interactive online repository, called IndAIR or Indian Air quality Interactive Repository. The repository is one of few such facilities in the world and has the maximum number of studies-262 concerning Delhi-NCR.
- Aim: to make air quality research and studies in an easily accessible web format for the public, media, researchers and academics. It is the first comprehensive effort to enlist existing Indian research and analysis on air pollution, its causes and effects.
- IndAIR has archived scanned documents from pre-Internet times (1950-1999), research articles, reports and case studies, and over 2,000 statutes to provide the history of air pollution research and legislation in the country. It includes all major legislations in the country dating back to 1905.
- It began to document important milestones in India to make them available to public, help academicians and also enable policy-makers to frame legislations. The web facility would also be a useful platform for scientific community to share its current work and exchange ideas.
| CSIR-National Environmental Engineering Research Institute (CSIR- NEERI) |
CSIR-NEERI is a research institute created and funded by Government of India. It was established in Nagpur in 1958 with focus on water supply, sewage disposal, communicable diseases and to some extent on industrial pollution and occupational diseases found common in post-independent India.
|
Condition of Air pollution in India
According to the WHO‘s Global Air Pollution Database in Geneva that monitors more than 6000 world cities following comments were made on India:
- 14 out of 20 most polluted cities in the world are from India.
- Delhi is the most polluted capital of the world.
- 98% of cities in low- and middle-income countries with more than 100,000 inhabitants do not meet WHO air quality guidelines. However, in high-income countries, that percentage decreases to 56%.
2024 IQAir Visual’s – World Air Quality Report:
Air quality has worsened in many regions worldwide. Air pollution causes millions of premature deaths annually. Bangladesh is the most polluted country, followed by Pakistan, India, Tajikistan, and Burkina Faso.
India’s Air Quality in 2024
- In April 2024, 215 out of 255 cities had PM2.5 levels below India’s daily NAAQS.
- Only 5 cities met the WHO’s daily safe limit of 15 µg/m³.
- Monthly PM2.5 levels in 95 out of 98 cities exceeded WHO’s daily guideline.
- Most polluted Indian cities: Visakhapatnam, Byrnihat, Durgapur, and Sasaram.
Impact on Health
According to the Lancet Commission on Pollution and Health most pollution linked deaths occur in India compared to anywhere else in the world.
Acute Respiratory Infections (ARIs)
Acute Respiratory Infections (ARIs) are serious ailment that prevents normal breathing function and kills an estimated 2.6mn children annually.
- “When you breathe in polluted air, particles and pollutants penetrate and inflame the linings of your bronchial tubes and lungs. This leads to respiratory illness such as chronic bronchitis, emphysema, heart disease, asthma, wheezing, coughing and difficulty in breathing. Children seem to be most vulnerable to the harmful effects of air pollution”.
- Pregnant women, babies and the elderly are at great risk.
Acute Respiratory infections (ARIs) account for about 70% of morbidity in 2018 which was highest in the communicable disease category leading to 27% mortality.
- Andhra Pradesh, Gujarat, Karnataka, Kerala, Tamil Nadu, UP & W. Bengal reported a large number of patients and fatalities due to ARI as per National Health Profile – 2019.
Comprehensive Environmental Pollution Index (CEPI)
It has been developed by the CPCB to characterize the environmental quality at a given location (industrial sectors). It is intended to act as an early warning tool and helps in categorizing the industrial clusters/areas in terms of priority of planning needs for interventions.
It captures the various health dimensions of environment including air, water and land, which is a function of the:
- Emissions (air pollutants)
- Effluents (water pollutants)
- hazardous wastes generated and
- Consumption of resources.
It is based on parameters such as the nature of toxins, the scale of industrial activities, the level of ambient pollution, impact on humans and eco-geological features and the number of people potentially affected within a 2 km radius.
Four-colour classification (Red, Orange, Green, White) scheme of industrial sectors based on the Pollution Index (CEPI); Four Colours: Based on Range of Pollution Index, Industrial sectors have been organized as:
- Red category: PI score of 60 and above. These are severe polluting industries. Total 60 industries including sugar, thermal power plants, paints and others are under in it.
- Orange category: PI score of 41 to 59. They’re moderately polluting industries. Total 83 industries like coal, washeries and automobile servicing are placed under it.
- Green category: PI score of 21 to 40. They are significantly low polluting industries. Total 63 industries are under in it.
- White category: PI score below and up to 20. They are non-polluting industries. A total 30 industries are under it. These industries are exempted from the requirement of the environment.
