Kolkata: The city's skyline may dazzle with light during Diwali, but beneath the sparkle lies a darker reality. The shift from high-decibel firecrackers to so-called "light, green" fireworks has not eased the city's pollution burden.
Instead, it has deepened the haze. Experts warn that the illusion of safety around these pyrotechnics is worsening air quality at a time when the city's atmosphere is least capable of dispersing pollutants.
Over the last few years, regulatory crackdowns and court directives curbed use of noisy, high-decibel crackers. But this shift did not translate into cleaner air. The streets and rooftops now light up with dazzling "fountains", sparklers, and colourful aerial fireworks.
These "light" crackers may emit less sound, but their smoke and chemical output remain heavy, spewing fine particulate matter (PM2.5) and toxic gases into the air.
"People often think switching from noisy bombs to light fireworks is an eco-friendly choice. In reality, smoke load worsens," said WBPCB chairman Kalyan Rudra. "Diwali these days is more about smog than sound. Colours are not possible without heavy metals in the fireworks."
Compounding the problem is the claim that "green" fireworks reduce emissions by 30%. Marketed as an environment-friendly alternative, these crackers were introduced under the supervision of National Environmental Engineering Research Institute to reduce particulate load and heavy metals. But, in practice, experts argue that the reduction is marginal, inconsistent, and insufficient to address the gravity of the crisis.
"Even if we accept the claim of a 30% reduction, it does little in a city already choking on smoke from vehicles, construction, and stubble-burning," said Naba Dutta, a campaigner against any firework-revelry. "In reality, monitoring stations continue to record sharp spikes in PM2.5 and PM10 every Diwali," he added.
Kolkata's air quality typically deteriorates on Diwali night and in the days that follow. Monitoring stations show PM2.5 levels going up to ten times the permissible limit.
Once the pollutants accumulate, they linger due to cool, dry conditions and low wind speed in Oct–Nov.
Doctors warn of immediate spikes in asthma attacks, respiratory infections, and eye irritation, nervous debilities, and mental issues after Diwali. "Every sparkler adds to the invisible cloud we all breathe," said Debasish Basu, a preventive medicine specialist. "A truly bright Diwali is one where lights shine but lungs do not suffer."