Air Quality Index (AQI) and (SAFAR)

The Air Quality Index (AQI) and System of Air Quality and Weather Forecasting and Research (SAFAR) are two interlinked initiatives developed in India to monitor, assess, and communicate air quality in real time. They form part of the government’s broader strategy to address the growing issue of air pollution and to provide the public with accessible information about the state of the atmosphere. Together, they represent a significant step in scientific environmental management and public health awareness in the country.

Background

Air pollution emerged as a major environmental and health concern in India during the late twentieth and early twenty-first centuries. Rapid urbanisation, industrialisation, vehicular growth, and fossil fuel dependence led to a consistent rise in atmospheric pollutants such as particulate matter (PM₂.₅ and PM₁₀), nitrogen oxides (NOₓ), sulphur dioxide (SO₂), ozone (O₃) and carbon monoxide (CO).
To assess and communicate air quality in a comprehensible form, the Central Pollution Control Board (CPCB) under the Ministry of Environment, Forest and Climate Change (MoEFCC) developed the National Air Quality Index (AQI) in 2014. Around the same time, the Indian Institute of Tropical Meteorology (IITM), Pune, under the Ministry of Earth Sciences (MoES), developed the SAFAR system to complement AQI by integrating real-time monitoring with short-term forecasting of air quality and weather.

Air Quality Index (AQI): Concept and Structure

The Air Quality Index is a composite measure that converts complex air pollution data of multiple pollutants into a single numerical and colour-coded indicator. It provides a simple way for the public to understand the overall level of air pollution and its potential health impacts.
Key features of AQI:

• The index is based on eight pollutants: PM₁₀, PM₂.₅, NO₂, SO₂, CO, O₃, NH₃, and Pb (lead).
• Each pollutant’s concentration is converted into a sub-index based on established health breakpoints.
• The worst sub-index among all pollutants determines the overall AQI value for a location.
• The AQI uses six colour-coded categories, each indicating a different level of health concern.

The AQI thus translates quantitative pollution data into qualitative information that can guide citizens, policymakers, and health professionals.

System of Air Quality and Weather Forecasting and Research (SAFAR)

SAFAR (System of Air Quality and Weather Forecasting and Research) is a scientific initiative launched by the Ministry of Earth Sciences and developed by the Indian Institute of Tropical Meteorology (IITM), Pune) in collaboration with the India Meteorological Department (IMD) and the National Centre for Medium Range Weather Forecasting (NCMRWF).
It is designed to provide real-time air quality monitoring and short-term (1–3 day) forecasting for major metropolitan cities in India. The project operates through an integrated network of advanced sensors and meteorological models.
Major objectives of SAFAR:

• To generate real-time measurements of air pollutants and meteorological parameters.
• To forecast air quality for up to 72 hours using advanced chemical transport models.
• To provide early warning for extreme pollution events and facilitate policy response.
• To communicate air quality data and forecasts to the public in an easily understandable form through digital and display platforms.

Cities covered under SAFAR: Initially implemented in Delhi, the network was later expanded to Pune, Mumbai, Ahmedabad, Bhopal, and other metropolitan regions. Each city’s SAFAR network includes multiple monitoring stations covering residential, traffic, background, and industrial areas.

Technology and Functioning

SAFAR integrates a variety of tools and datasets:

• Automatic Air Monitoring Stations: These measure key pollutants (PM₁₀, PM₂.₅, CO, O₃, NO₂, SO₂, and black carbon) and meteorological parameters (temperature, wind, humidity, solar radiation).
• Emission Inventory Models: Detailed sector-wise databases of emission sources—vehicular, industrial, biomass burning, and dust—are compiled for each city.
• Atmospheric Chemistry Models: These models simulate pollutant dispersion and chemical transformation using meteorological data to produce forecasts.
• Public Information Systems: Data are disseminated via mobile applications, web dashboards, LED display boards at public places, and media updates.

SAFAR is thus both a monitoring and forecasting system, providing early warning of potential high-pollution episodes.

Importance and Applications

• Policy Support: The AQI-SAFAR system provides crucial input for government agencies and municipal bodies in implementing air pollution control measures such as traffic restrictions, construction bans, or industrial shutdowns during high-pollution periods.
• Public Health Awareness: Real-time AQI updates enable citizens to take protective measures—such as avoiding outdoor activities, using masks or air purifiers—during pollution peaks.
• Research and Planning: The data support long-term studies on urban air pollution sources, transport patterns, and the effectiveness of mitigation measures.
• Emergency Response: SAFAR’s forecasting component helps issue timely warnings to sensitive groups such as children, the elderly and patients with respiratory illnesses.
• Educational and Outreach Value: The AQI-SAFAR system promotes public understanding of environmental health and the importance of sustainable urban practices.

Advantages and Limitations

Advantages:

• Simplifies complex air pollution data into understandable indices.
• Provides both real-time and predictive information.
• Enables evidence-based policymaking.
• Covers multiple pollutants simultaneously.
• Enhances public engagement and awareness about air quality.

Limitations:

• AQI represents an average value for an area and may not capture micro-level variations.
• The network coverage, while growing, remains limited to major cities.
• Maintenance and calibration of sensors require constant technical support.
• Forecast accuracy may vary with meteorological uncertainty and regional emission variability.

Recent Developments

• SAFAR networks have been continuously upgraded with improved modelling techniques, higher-resolution emission inventories, and integration with satellite observations.
• Mobile-based applications such as “SAFAR-Air” now provide instant AQI updates, pollutant-wise data, and health advisories.
• The AQI framework is being extended to smaller cities under the National Clean Air Programme (NCAP), which aims to reduce particulate pollution by 20–30 % in 122 non-attainment cities.
• Research collaborations are exploring links between air quality data, climate variables, and public health outcomes to design more effective interventions.