Published on: November 11, 2025

AIR QUALITY BEYOND AQI: WHY MEASURING INDOOR POLLUTANTS MATTERS

AIR QUALITY BEYOND AQI: WHY MEASURING INDOOR POLLUTANTS MATTERS

Introduction

Air pollution has emerged as one of the gravest environmental challenges of the 21st century. While outdoor pollution garners most of the attention, a silent and often overlooked threat lies indoors. Studies show that indoor air can be two to five times more polluted than outdoor air, affecting the health of millions who spend nearly 90% of their time inside homes, offices, or other enclosed spaces.

Understanding Air Pollution

Air pollution refers to the presence of harmful substances in the air, including gases, particulates, and biological molecules that pose health and environmental risks.

Sources of Air Pollution

  1. Outdoor Sources:

    • Vehicular emissions, industrial activities, crop residue burning, and power plants.

  2. Indoor Sources:

    • Cooking smoke, incense sticks, cleaning agents, paints, synthetic air fresheners, and construction dust.

    • Poor ventilation traps these pollutants, worsening exposure levels.

The Concept of Air Quality Index (AQI)

The Air Quality Index (AQI) is a standardized tool used to communicate how polluted the air currently is or how polluted it is forecast to become.
It measures key pollutants like PM2.5, PM10, NO₂, SO₂, CO, O₃, and NH₃, and classifies air into six categories — Good, Satisfactory, Moderately Polluted, Poor, Very Poor, and Severe.

However, AQI primarily focuses on outdoor air, leaving the quality of indoor air largely unmonitored and unregulated.

The Hidden Threat of Indoor Air Pollution

A study by BITS Pilani Hyderabad’s BEST Lab highlights the dangers of indoor pollutants and the need for a new Indoor Air Quality (IAQ) scale.
The researchers correlated construction activities and household emissions with deteriorating IAQ, identifying pollutants such as:

  • PM2.5 and PM10 – from dust, construction, and combustion.

  • Carbon Monoxide (CO) – from cooking and heating.

  • Volatile Organic Compounds (VOCs) – from paints, cleaners, and fuels.

  • Nitrogen Oxides (NOx) – from stoves and nearby traffic.

  • Benzene and Radon – carcinogenic pollutants found in some household materials.

Benzene emerged as one of the most hazardous, followed by CO and VOCs.

Health Impacts of Poor Indoor Air Quality

Poor indoor air quality can cause Sick Building Syndrome (SBS) and trigger several ailments:

  • Short-term effects: Headaches, eye irritation, fatigue, and dizziness.

  • Long-term effects: Asthma, COPD, heart disease, reduced immunity, and even cancer.

  • Vulnerable groups: Women, infants, and elderly people are most at risk due to prolonged indoor exposure.

Government Initiatives on Air Pollution

India has launched several programs to combat air pollution:

  1. National Clean Air Programme (NCAP) – aims to reduce PM2.5 and PM10 levels by 40% by 2026.

  2. Graded Response Action Plan (GRAP) – for Delhi-NCR to tackle severe pollution episodes.

  3. National Air Quality Monitoring Programme (NAMP) – monitors outdoor air quality across cities.

  4. Smart Cities Mission – includes measures for clean air and sustainable mobility.

However, indoor air quality standards and monitoring mechanisms are still missing in national frameworks.

Policy Recommendations and Way Forward

  1. Include IAQ Standards in building codes and workplace safety regulations.

  2. Promote Green Construction Practices to minimize dust and emissions.

  3. Encourage Public Awareness on indoor pollutants and their health effects.

  4. Adopt Technological Solutions such as IAQ sensors and air purification systems.

  5. Household Measures:

    • Increase ventilation during low-pollution hours.

    • Use exhaust fans while cooking.

    • Reduce incense and candle use.

    • Add indoor plants and avoid harsh chemical cleaners.

Conclusion

Indoor air pollution is an invisible but significant health risk. While India’s focus on outdoor AQI has improved awareness, the next frontier lies indoors. Recognizing, regulating, and mitigating indoor pollutants is essential to achieving comprehensive environmental and public health goals. As urbanization and construction expand, addressing IAQ will be key to building truly sustainable and livable cities.

MAINS QUESTIONS

  1. What is the significance of indoor air pollution in the context of India’s public health challenge? How can policy interventions help mitigate its impact?
  2. Critically evaluate the effectiveness of India’s Air Quality Index in addressing overall air pollution. Should Indoor Air Quality (IAQ) standards be integrated into it?