National Ambient Air Quality Monitoring in India: Methods, Standards, and Future Outlook

Air is the invisible lifeline that sustains all forms of life. Yet, in 2025, India continues to struggle with severe air quality challenges that directly affect human health, ecosystems, and economic productivity. Ambient Air Monitoring plays a crucial role in understanding pollution trends, enforcing regulations, and guiding policy actions.

Why Ambient Air Monitoring Matters

Ambient air monitoring is the process of measuring pollutants present in outdoor air to assess their compliance with prescribed standards. It provides real-time and long-term data to:

• Identify pollution hotspots
• Evaluate compliance with national standards
• Develop effective air quality management strategies
• Inform citizens about health risks

In India, ambient air monitoring is carried out in line with guidelines laid down by the Central Pollution Control Board (CPCB) under the Ministry of Environment, Forest and Climate Change (MoEF&CC).

CPCB Testing Methods for Ambient Air Quality

CPCB prescribes specific testing methods for each pollutant under the National Ambient Air Quality Standards (NAAQS), 2009. These methods are based on scientific accuracy, cost-effectiveness, and feasibility for Indian conditions.

Key Pollutants and CPCB Testing Methods

1. Particulate Matter (PM₁₀ & PM_2.5):
• Gravimetric method using High Volume Sampler (PM₁₀) and Fine Particulate Sampler (PM_2.5).
• Beta Attenuation Monitors (BAM) for continuous monitoring.
2. Sulphur Dioxide (SO₂):
• Improved West & Gaeke method (manual).
• UV Fluorescence method (continuous).
3. Nitrogen Dioxide (NO₂):
• Modified Jacob & Hochheiser method (Na- Arsenite).
• Chemiluminescence method (continuous).
4. Ozone (O₃):
• UV Photometric method.
• Chemiluminescence method
• Chemical Method
5. Carbon Monoxide (CO):
• Non-Dispersive Infrared (NDIR) Spectroscopy.
6. Heavy Metals (Lead, Nickel, Arsenic, etc.):
• Atomic Absorption Spectrophotometry (AAS).
7. Ammonia (NH₃):
• Indophenol Blue method.
• Chemiluminescence

CPCB operates the National Air Quality Monitoring Programme (NAMP) through a network of manual stations and Continuous Ambient Air Quality Monitoring Stations (CAAQMS) across urban and industrial clusters.

CPCB Ambient Air Quality Limits

The NAAQS, 2009, specifies the following annual average limits (µg/m³):

India’s Air Pollution Scenario in 2025

Despite policy interventions, India remains one of the most polluted countries in the world. According to early 2025 data from CPCB and independent monitoring:

1. Northern India continues to face severe winter smog episodes due to stubble burning, vehicular emissions, and unfavourable meteorology. Delhi, Ghaziabad, and Lucknow remain in the “Severe” AQI category for multiple days each year.
2. Industrial Clusters such as Singrauli, Korba, and Angul report high SO₂ and PM levels due to coal-based power plants.
3. Tier-2 and Tier-3 cities (like Varanasi, Patna, and Ludhiana) are showing rising PM_2.5 levels, highlighting the spread of pollution beyond metros.
4. Southern and coastal cities (like Chennai, Kochi, and Visakhapatnam) fare relatively better but are witnessing increased ozone levels due to vehicular and industrial activities.
5. Policy Push: The National Clean Air Programme (NCAP) is targeting a 40% reduction in PM levels by 2026, but progress is uneven across states.

According to the Centre for Research on Energy and Clean Air (CREA), air quality across India showed notable improvement in July 2025, largely due to increased rainfall.

• Compliance with Indian Standards: Out of 236 cities with reliable CAAQMS data (>80% data availability), 233 cities met India’s NAAQS daily PM_2.5 limit of 60 µg/m³.
• Compliance with WHO Guidelines: Only 59 cities stayed within the WHO’s daily safe guideline of 15 µg/m³, highlighting the significant gap between national and global standards.

NCAP vs Non-NCAP Cities

• NCAP Cities: Among 96 monitored NCAP cities, only one city exceeded India’s daily PM_2.5 limit, but 81 cities crossed the WHO’s guideline.
• Non-NCAP Cities: Of 140 monitored non-NCAP cities, 96 exceeded the WHO’s limit, while just two cities breached India’s NAAQS.

AQI Categories (National)

• Good (0–30 µg/m³): 208 cities
• Satisfactory (31–60 µg/m³): 25 cities
• Moderate (61–90 µg/m³): 3 cities

Most Polluted Cities in July 2025

• Nandesari (Gujarat): Worst performer with 86 µg/m³ PM_2.5, exceeding NAAQS on 96% of days.
• Byrnihat (Meghalaya): 70.8 µg/m³.
• Araria (Bihar): 60.5 µg/m³.

Cleanest City

• Aizawl (Mizoram): Recorded the lowest  PM_2.5 at just 2 µg/m³.

Megacities

• Major metro cities including Delhi, Chennai, Mumbai, Kolkata, and Bengaluru all reported monthly average  PM_2.5 levels below the NAAQS threshold.

But “According to CPCB’s 2025 NAMP data and the IQAir World Air Quality Report 2025, Indian cities like Delhi, Ghaziabad, and Patna remain among the most polluted globally, with annual  PM_2.5 levels exceeding both India’s NAAQS and WHO limits.”

 Way Forward

1. Stricter Standards: India needs to gradually align with WHO guidelines to ensure health protection.
2. Expanded Monitoring Network: More CAAQMS stations must be installed in smaller cities and rural belts.
3. Source Apportionment: Identifying pollution sources with high-resolution monitoring and satellite data.
4. Citizen Awareness: Public disclosure of AQI data and community participation in local clean air drives.
5. Sectoral Interventions: Transition to cleaner fuels, EV adoption, industrial emission norms, and better agricultural practices.

 Conclusion

Ambient air monitoring is not just a regulatory tool—it is a public health safeguard. While India has developed a robust monitoring framework under CPCB and NAMP, the 2025 reality shows that enforcement, stricter limits, and innovative solutions are urgently needed. The path to cleaner air will require coordinated efforts from government, industry, and citizens alike.

At Virat Global Lab, a division of Aseries Envirotek India Private Limited, we are committed to safeguarding the air you breathe.
With advanced CPCB-approved testing methods, state-of-the-art monitoring equipment, and expert scientists, we help industries, institutions, and communities stay compliant while protecting public health.

Whether it’s ambient air monitoring, source emissions, or compliance reporting, we provide accurate, reliable, and NABL-accredited services across India.

Take a step towards cleaner air today.
Connect with Virat Global Lab for your ambient air testing and compliance needs — because healthier air means healthier lives.

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