Green Firecrackers, Explained: What CSIR-NEERI Actually Changed, What It Didn’t
Every Diwali for the last seven years, Indian courts, governments and citizens have argued the same question: are “green firecrackers” enough? Developed by CSIR-NEERI (the National Environmental Engineering Research Institute) in Nagpur from around 2018, these crackers are designed to reduce emissions by roughly 30% compared with conventional firecrackers. They are not zero-emission. They are not silent. They produce less PM2.5, PM10, SO₂ and NOx — but still produce all of them. The Supreme Court’s October 2025 ruling permits regulated green-cracker use in Delhi-NCR for a 5-day window; whether this represents a workable compromise depends on whose definition of “workable” you use. This page lays out the technology, the regulation, and the air-quality impact.
Key numbers
- ~30% — emission reduction (PM2.5, PM10) for CSIR-NEERI green crackers vs. conventional
- ~10% — reduction in gaseous emissions (SO₂, NOx)
- 3 categories — SWAS (Safe Water Releaser), STAR (Safe Thermite Cracker), SAFAL (Safe Minimal Aluminium)
- 18–21 October 2025 — Supreme Court-permitted Delhi-NCR cracker window
- 6–7 AM and 8–10 PM — restricted hours
- <1% annual / 20–35% on Diwali night — firecracker contribution to Delhi PM2.5
What CSIR-NEERI actually changed
Conventional firecrackers contain:
- Oxidisers (typically potassium nitrate, ammonium perchlorate)
- Fuel (charcoal, sulphur)
- Metal salts (for colour — barium, copper, strontium, lithium, etc.)
- Aluminium powder (for brightness and noise)
- Binders (organic compounds, dextrin)
Combustion produces:
- PM2.5 from incomplete burning
- SO₂ from sulphur
- NOx from high-temperature reactions
- Metal oxide aerosols (barium oxide, copper oxide, etc.)
- CO and CO₂
- Heavy metal fallout
CSIR-NEERI’s three formulations reduce emissions through different mechanisms:
1. SWAS (Safe Water Releaser). Contains a water-releasing component that suppresses dust and reduces particulate emissions by approximately 30%. The water vapour also reduces SO₂ and NOx slightly.
2. STAR (Safe Thermite Cracker). Replaces the conventional oxidiser-fuel combination with a thermite reaction. Reduces sulphur and ammonium-related emissions. Generates less smoke per unit “boom.”
3. SAFAL (Safe Minimal Aluminium). Replaces conventional aluminium content with charcoal in some compositions. Reduces metal-aerosol emissions.
All three are designed for 30% lower particulate emissions and 10% lower gaseous emissions vs. their conventional equivalents, per CSIR-NEERI laboratory testing.
What they didn’t change
Green crackers still:
- Produce PM2.5 — substantial, just less than before
- Produce noise — modestly quieter (some claim 30% noise reduction; user perception varies)
- Use heavy metals for colour
- Burn for atmospheric impact — the firework effect requires combustion
- Drift downwind — Delhi NCR’s late-October winds carry the fallout for kilometres
- Concentrate emissions in 4–6 hours — the festival timing intensity is the same
A green cracker is to a conventional cracker roughly what a low-tar cigarette is to a regular one: meaningfully better per unit, still harmful, and the harm scales with how many are used.
The Supreme Court’s 2024–25 trajectory
October 2024: Delhi government imposed complete firecracker ban (manufacture, sale, use) in light of severe air-quality forecasts.
December 2024: Supreme Court upheld the ban and extended the principle to Haryana, UP, Rajasthan.
October 2025: The Supreme Court reserved verdict on a Union government proposal for a 5-day trial of green firecracker sales and use during Diwali in Delhi-NCR. The court’s October 15, 2025 ruling permitted:
- Sale and use of certified green crackers only
- Window: 18–21 October 2025
- Daily hours: 6–7 AM and 8–10 PM
- Enforcement: state governments
The decision was framed as a balance between public health, livelihoods of the firecracker industry (concentrated in Sivakasi, Tamil Nadu, employing ~500,000), religious sentiment, and the practical impossibility of fully enforcing a total ban.
The air-quality math
Delhi NCR’s normal Diwali night without firecrackers would still have elevated PM2.5 — from stubble fires, vehicles, and the late-October seasonal regime. Diwali firecrackers add on top.
Historical Diwali nights (with conventional crackers, no ban): - Pre-Diwali AQI: typically 200–300 - Diwali night peak: 400–600 (sometimes 800+) - Increase attributable to crackers: 20–35%
A “green-only” Diwali should reduce that 20–35% increase to roughly 15–25% — assuming compliance. The compliance assumption is large. Past surveys have consistently found:
- Wide availability of conventional crackers even during ban years
- Limited differentiation between green and conventional at retail
- Enforcement focused on small fines for users, not on supply-side interruption
What the green-cracker debate misses
Three under-discussed points:
1. Annual contribution is small. Firecrackers contribute <1% of Delhi’s annual PM2.5. The peak-night impact is large; the average-year impact is small. Banning crackers without addressing the 99% other sources doesn’t solve Delhi’s air-quality problem.
2. The cultural and livelihood dimension is real. Sivakasi’s firecracker industry employs ~500,000 people, mostly in Tamil Nadu. Festival use is a culturally embedded practice with religious overtones. Outright bans without alternatives generate compliance failure and political backlash.
3. The local-vs-regional impact is asymmetric. A child playing safely with a single phuljhari (sparkler) does negligible regional harm. A neighborhood firing aerial cake-bombs for an hour creates substantial local PM2.5 spikes. Policy targeting the high-impact uses (aerial, multi-stage) while permitting lower-impact uses might be more enforceable than blanket bans.
What residents can do
Five practical responses:
1. Treat Diwali night and the day after as high-AQI events regardless of cracker policy. Whether crackers are banned, restricted, or freely permitted, peak Diwali AQI will be unhealthy. Plan accordingly.
2. Stay indoors during peak burning hours (typically 7–11 PM Diwali night). Especially for children, asthmatics, elderly, and pregnant women.
3. Keep windows closed for 24–48 hours. The outdoor PM2.5 spike persists into the next day; sealed homes with mechanical ventilation continue to deliver clean air through this.
4. Run kitchen and bathroom exhausts only briefly. On peak nights, running exhausts pulls unfiltered outdoor air in. Use sparingly.
5. Trust the fresh-air system. An H13 HEPA filtered positive-pressure system holds indoor PM2.5 under 10 µg/m³ regardless of outdoor conditions, including peak Diwali. Children can sleep through the night without the next-day breathing irritation that ungentle Diwali traditionally produces.
FAQ
Are green crackers safe? Safer per unit than conventional. Not safe in absolute terms. Burning anything indoors or in concentrated quantity outdoors still produces meaningful health-relevant emissions.
How do I know if a cracker is actually a green cracker? PESO (Petroleum and Explosives Safety Organisation) certification + a QR code on packaging. Without these, assume conventional. Visible green-label crackers are increasingly common in regulated markets but counterfeiting is reported.
Did the 5-day window in 2025 reduce pollution? Partial. Compliance with green-only and timing restrictions was uneven. AQI on Diwali night was elevated but lower than uncontrolled years.
Should Diwali fireworks be banned entirely? Public-health argument for yes; livelihood, cultural, and enforcement arguments for no. Different reasonable people reach different answers; this is genuinely contested policy.
Are sparklers and phuljhari included in the ban? Generally permitted under “green” classification with restrictions. Specific rules vary by state and year.