Chemistry Of Cracker Smoke: What’s Really In The Air After Diwali Night?

What’s in Cracker Smoke? Breaking Down the Chemistry

Every time a firecracker explodes, it releases a mix of particles and gases into the atmosphere. This includes:

• Particulate matter (PM), especially PM2.5 (particles smaller than 2.5 micrometres) and PM10 (particles smaller than 10 micrometres), which can travel deep into the lungs.
• Gaseous pollutants like sulphur dioxide, nitrogen dioxide, carbon monoxide, and ozone-forming compounds.
• Heavy metals and salts that are used for colour and sound in fireworks, such as barium, copper, strontium, aluminium, potassium, and lead.
• Volatile organic compounds (VOCs) that form smog and irritate airways.

Each colour in the fireworks has a chemical source – red comes from strontium salts, green from barium, blue from copper compounds, and gold from iron or charcoal. When these burn, they don’t disappear. They disperse in microscopic forms, coating the air and, eventually, our lungs.

What Studies Say About Air Quality Post-Fireworks

Multiple Indian cities have shown sharp increases in air pollution levels immediately after Diwali night. A study in Delhi recorded that PM2.5 levels rose over 250 percent compared to baseline levels before fireworks began.

These spikes happen rapidly — often within just an hour or two after sunset — and can last for more than 24 hours, especially when the wind is slow and humidity is high.

In cities like Mumbai, Kolkata, Ahmedabad, and Bengaluru, researchers have tracked consistent patterns of sharp rises in sulphur dioxide, nitrogen dioxide, and elemental carbon during Diwali. These not only cross permissible limits set by the Central Pollution Control Board but also linger well into the next day.

In coastal cities, the impact can differ slightly due to sea breezes, but studies still show that PM2.5 levels during Diwali often exceed 180 micrograms per cubic meter — more than three times the safe limit.

One chemical speciation study found that during Diwali, particles contained higher-than-usual levels of zinc, lead, aluminium, potassium, and nitrates — all of which are indicators of firework combustion.

The Real Danger: What Happens in Your Body

Particulate matter is not just dust. PM2.5 can travel deep into the respiratory system, reach the alveoli in the lungs, and even cross into the bloodstream. Once inside, these particles can trigger oxidative stress, inflammation, and impair organ function.

Exposure to firework-related pollutants has been linked to:

• Increased asthma attacks and breathing issues, especially in children and the elderly.
• Worsening of chronic obstructive pulmonary disease (COPD).
• Increased risk of heart attacks due to higher blood pressure and inflammation.
• Reduced lung function in both short- and long-term exposures.
• Disruption of sleep due to cough, sore throat, and nasal congestion.

One laboratory study exposed human lung cells to PM2.5 collected after Diwali and found increased DNA damage and oxidative stress, confirming the biological harm from this kind of pollution.

The danger isn’t uniform — the people most at risk include children (who breathe more air per kilogram of body weight), the elderly, people with existing lung or heart issues, and even outdoor workers and police personnel deployed during Diwali.

How Long Does the Pollution Last?

The worst of the pollution from fireworks typically lasts for about 6 to 12 hours after bursting begins, but in places like Delhi or Lucknow, it can stretch up to 48 hours, depending on weather. Low wind speeds, winter fog, and temperature inversion (when cool air gets trapped near the ground under a layer of warmer air) worsen the situation. Pollutants that would otherwise dissipate stay stuck close to breathing level.

This makes the early morning after Diwali a particularly bad time to go for a walk or a jog.

Is “Green” Really Green?

In recent years, the government has promoted “green crackers” — fireworks that are supposed to emit 30 percent less particulate matter and reduce harmful gases. These crackers replace some of the toxic substances with alternative chemicals. For example, potassium nitrate may be used instead of barium nitrate, and charcoal may be reduced or eliminated.

However, even green crackers are not entirely clean. Studies have shown they still emit PM2.5, metal ions, and gases — just in lesser amounts. Their impact on air quality is still significant, especially when burst in large numbers.

Moreover, due to poor labelling and rampant mixing with regular fireworks, it’s hard for consumers to be sure what they’re buying.

What You Can Do to Breathe Easier

1. Avoid standing near bursting points. Smoke is densest near the source — the closer you are, the more you inhale.
2. Use N95 or higher-grade masks, not cloth masks, when outdoors on Diwali night.
3. Stay indoors after fireworks and avoid morning walks on the day after. Use air purifiers if available.
4. Support community bursting events with time limits and shared spaces instead of scattered, individual fireworks.
5. Advocate for certified green crackers and stricter enforcement.
6. Check air quality apps before stepping out, especially if you’re vulnerable.

Cultural Joy vs Public Health: Finding the Balance

Fireworks are deeply embedded in Indian festive culture. For many, Diwali is incomplete without the crackle of crackers. But the cost of that joy is becoming clearer each year — as emergency rooms fill up, cities vanish into smog, and millions breathe air worse than any industrial zone.

Balancing tradition with safety will take more than just awareness — it requires city-level planning, stronger enforcement of bans, regulated sale of fireworks, and above all, collective community decisions.

Because when the joy fades and the lights go out, the haze that remains doesn’t just darken the sky — it enters our lungs, our blood, and our future.