India’s Controversial Air Quality Standards: Why Pollution Levels Are Limited to 500 Despite Greater Toxicity
For millions living in northern India, the air quality in November poses a significant challenge, with ashy air and hazy skies becoming a daily reality. Many residents begin their mornings by checking air quality readings, but the numbers they encounter can vary dramatically depending on the source. Government-supported applications like SAFAR and SAMEER report air quality index (AQI) levels that cap at 500, while private and international platforms such as IQAir frequently display much higher readings, sometimes exceeding 1,000. This discrepancy raises critical questions about which data can be trusted and why India does not officially report air quality beyond the 500 mark.
Understanding India’s Air Quality Index
India’s official air quality scale categorizes readings above 200 as posing clear breathing discomfort for most individuals with prolonged exposure. Levels between 400 and 500 are classified as “severe,” impacting even healthy individuals while posing serious risks to those with pre-existing health conditions. However, the AQI scale does not extend beyond 500, a limit established over a decade ago when the National Air Quality Index was introduced. This cap was initially intended to prevent public panic, as exceeding this threshold indicated a dire situation requiring immediate action. Gufran Beig, the founder director of SAFAR, acknowledges that this approach simplifies the data, treating all readings above 500 as equivalent, despite the actual pollution levels potentially being much higher. In contrast, international monitoring platforms do not impose such a cap, leading to significantly higher reported figures.
Global Standards and Local Definitions
The difference in air quality standards is not limited to the cap on the AQI. The World Health Organization (WHO) defines hazardous PM2.5 levels as exceeding 15 micrograms per cubic meter over a 24-hour period, while India’s threshold is set at 60 micrograms. Experts point out that there is no universal formula for calculating AQI globally, as countries like the United States, China, and those in the European Union each have their own pollutant thresholds. Beig notes that WHO provides guidelines, but each nation adapts its index based on local conditions, making comparisons between India’s AQI and those of other countries potentially misleading.
Differences in Measurement Techniques
The instruments used to measure air quality also differ significantly. The Indian pollution control board employs Beta Attenuation Monitors (BAMs), which accurately measure the mass of airborne particles and adhere to strict calibration standards. In contrast, platforms like IQAir utilize sensor-based monitors that estimate particle counts using laser scattering and electrochemical methods. Abhijeet Pathak, a scientist with prior experience at the Indian pollution control board, explains that sensor-based monitoring has not received government approval in India. He emphasizes that the country’s air quality framework has not been thoroughly updated since 2009, and there is a growing call among environmental scientists and activists to recalibrate the AQI based on advancements in technology.
The Need for a Revised Air Quality Framework
Experts argue that revising the National Air Quality Index is essential to incorporate sensor-based data effectively. Beig advocates for removing the 500 cap, noting that research increasingly shows that health symptoms worsen as pollution levels rise. The current AQI system halts at 500 not because pollution levels cease to be a concern, but because the framework was designed with an upper limit. As air quality continues to deteriorate in many regions, addressing these discrepancies and updating the measurement standards is crucial for public health and safety.
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