Kolkata has entered a deeply worrying phase as its air quality deteriorated sharply over the past week, overtaking Delhi in pollution levels for seven consecutive days. The city, which is not traditionally known for extreme winter smog, found itself engulfed in thick, toxic air as the Air Quality Index (AQI) remained consistently higher than that of the national capital.
From December 6 to December 12, residents across Kolkata experienced hazardous breathing conditions as pollution levels rose dramatically. According to air quality monitoring data, the city’s AQI fluctuated between 184 and an alarming 439 during this period. These figures placed Kolkata repeatedly in the “very poor” and “severe” categories, levels considered harmful to all sections of the population.
This prolonged spell of poor air quality marks a significant shift for the city. While Delhi has long struggled with winter pollution due to stubble burning, vehicular emissions, and weather patterns, Kolkata’s worsening air highlights a growing environmental challenge that is no longer seasonal or isolated.
Severe and Hazardous AQI Peaks Raise Immediate Health Concerns
The situation reached a critical point on December 11 when Kolkata recorded one of its highest pollution readings in recent memory. At around 6:04 pm that evening, the AQI surged sharply, pushing large parts of the city firmly into the severe danger zone.
Conditions deteriorated further late into the night. In the last 24 hours alone, Kolkata registered a shocking AQI of 558 at approximately 11:04 pm on December 11. This level falls under the “hazardous” category, indicating air that is unsafe even for healthy individuals and poses serious risks with prolonged exposure.
During the same time frame, Delhi’s air quality, while still poor, remained comparatively lower. The national capital recorded AQI levels ranging between 172 and 345 over the week, with its worst recent reading touching 477 in the early hours of December 12. Even then, Kolkata’s pollution levels exceeded Delhi’s most severe measurements, underlining the gravity of the situation.
Pollution Control Board Silent as City Gasps for Breath
Despite the sharp escalation in pollution levels, the West Bengal Pollution Control Board has yet to issue an official statement addressing the crisis. Representatives of the pollution watchdog did not respond to calls seeking clarification on the worsening air quality.
This lack of official communication has added to public concern, especially since warning signs had already emerged weeks earlier. A previous analysis conducted in late November showed that Kolkata’s air quality was steadily declining, even as Delhi was battling its annual smog. At the time, the findings raised concerns. Now, those concerns have escalated into a full-blown alert.
Residents and health experts alike are questioning whether sufficient monitoring and preventive measures are in place as pollution becomes a recurring winter problem rather than an occasional anomaly.
Understanding AQI Levels and What They Mean for Public Health
Air Quality Index numbers provide a clear picture of the health risks associated with polluted air. An AQI between 51 and 100 is generally considered satisfactory, although sensitive individuals may experience mild discomfort. Levels between 101 and 200 can cause breathing difficulties for people with respiratory conditions.
Once AQI crosses 200, the risks become more widespread. The 201–300 range, categorized as “poor,” often leads to throat irritation, coughing, burning eyes, and breathlessness among the general population. The “very poor” category, ranging from 301 to 400, is associated with reduced lung function, inflamed airways, and frequent asthma attacks.
Any AQI reading above 400 is classified as “severe.” At this level, air pollution affects everyone, increasing the likelihood of chest tightness, persistent coughing, heart complications, and serious respiratory distress, particularly among those with existing health conditions. With Kolkata repeatedly crossing this threshold, doctors warn that the risks are no longer theoretical but immediate and real.
Long-Term Health Risks Mount as Experts Urge Precaution
One of the most alarming indicators of the current crisis is the cigarette-equivalent exposure metric. According to this measure, breathing Kolkata’s air over the last 24 hours is equivalent to smoking approximately 11.2 cigarettes a day. Over a week, this exposure adds up to more than 78 cigarettes, and over a month, more than 330.
Doctors stress that the true danger of air pollution lies in cumulative exposure. Pulmonologist Dr. Arup Halder of CMRI Kolkata explained that air pollution begins affecting health even before birth. Chronic exposure during pregnancy has been linked to premature delivery and low birth weight, leaving newborns more vulnerable to lifelong health issues.
With AQI levels crossing 500 in some areas, medical professionals are advising residents to limit outdoor activities, particularly children, pregnant women, senior citizens, and individuals with heart or lung disease. Masks and indoor air purifiers, once considered optional, are increasingly being seen as essential protective measures.
As winter deepens and wind speeds remain low, experts warn that pollutants trapped near the ground may not disperse quickly. Without a significant change in weather conditions or effective intervention, Kolkata may continue to struggle with dangerously polluted air, placing the city in an unfamiliar and deeply concerning position.
