Delhi’s green crackers are designed to reduce particulate and gaseous emissions, but the evidence available in the latest explainer shows that they are not pollution-free. Their lower use of aluminium, sulphur and potassium nitrate may reduce some emissions, yet a Delhi Technological University study cited by the Times of India found high concentrations of ultrafine particles, raising a more difficult question for the city: can a product be less polluting without being safe for urban air?
The question has acquired renewed importance because the Supreme Court has allowed green crackers in Delhi during specified windows of 6am to 7am and 8pm to 10pm on November 7 and 8. The permitted hours are intended to restrict when fireworks are used, while the green-cracker requirement is intended to limit their emissions. Together, the measures place the responsibility for cleaner celebrations on two separate controls: what people burn and when they burn it.
That distinction matters because the source material shows that both the product and the enforcement environment have limitations. Green crackers are designed to achieve at least a 30% reduction in particulate matter emissions and a minimum 10% reduction in gaseous emissions. They are also designed to produce noise levels below 125 decibels at a distance of four metres from the point of bursting. These are reductions against conventional crackers, not an assurance that the resulting air is clean or that the noise impact disappears.
The composition of green crackers is central to the difference. Conventional crackers contain 34% aluminium, 57% potassium nitrate and 9% sulphur. Green crackers contain 29% aluminium, 28% potassium nitrate, 38% of CSIR-NEERI’s proprietary material identified in the report as Fe₂O₃, and 5% sulphur. Compared with conventional products, the reported formulation uses 14% less aluminium, 50% less potassium nitrate and 44% less sulphur. The stated result is a 30% reduction in particulate matter emissions.
The formulation also changes the economics of one important input. The flash powder used in conventional crackers costs ₹132 per kg, compared with ₹95 per kg for green crackers, according to the report. That difference indicates that the lower-emission option is not necessarily more expensive at the level of this component. However, price alone does not establish whether products sold in the market comply with the required formulation or whether restrictions are being followed at the point of use.
For consumers, the identification system is supposed to address that problem. Green crackers carry a green logo from the Council of Scientific and Industrial Research-National Environmental Engineering Research Institute and the Petroleum and Explosives Safety Organisation, along with encrypted QR codes. The marking is intended to help distinguish approved products from conventional crackers. The supplied report does not establish how consistently these identifiers are checked in retail markets or how effectively enforcement agencies act when products are sold or used outside the permitted conditions.
The most important qualification in the evidence concerns particles that are not always visible in public discussion about firecrackers. A study by Delhi Technological University, cited in the report, found that green crackers produce high concentrations of ultrafine particles. These particles are smaller than PM2.5 and PM10, the particulate categories more commonly discussed in public air-quality debates. The report describes ultrafine particles as more dangerous than PM2.5 and PM10, but does not provide the study’s measured concentrations or explain the precise health outcomes assessed. What it does establish is that lower reported emissions do not remove the need to examine the type and size of particles released.
The contrast with conventional crackers is stark in the short range around a burst. Measurements recorded within one to six feet showed PM2.5 concentrations of 64,500 micrograms per cubic metre for a snake tablet and 38,450 micrograms per cubic metre for a garland of 1,000 crackers. A pulpul recorded 28,950 micrograms per cubic metre, while a full-hand sparkler recorded 10,390 micrograms per cubic metre. Ground spinners, or chakris, recorded 9,490 micrograms per cubic metre, and flower pots, or anars, recorded 4,860 micrograms per cubic metre.
These figures are not citywide averages. They are measurements taken close to the point of bursting, so they describe intense local exposure rather than the overall pollution level across Delhi. That distinction is important for interpreting the data. A lower-emission product may reduce the concentration released by an individual cracker, but the overall urban effect will also depend on how many crackers are used, where they are used, weather conditions and whether the permitted hours are respected. The supplied material does not provide a calculation linking the reported product-level reductions to citywide pollution levels.
Delhi’s own record shows why regulation has repeatedly returned to the centre of the Diwali pollution debate. In 2015, when no firecracker ban was in place, the reported readings for November 10, 11 and 12 were 353, 343 and 360. In 2016, the readings for October 29, 30 and 31 were 404, 431 and 445. The figures changed under later restrictions, but they continued to show severe pollution around the festival period.
In 2017, the Supreme Court banned the sale of firecrackers for the first time in Delhi. The readings for October 18, 19 and 20 were 302, 319 and 403. In 2018, a nationwide restriction allowed only green crackers, and the readings for November 6, 7 and 8 were 338, 281 and 390. In 2019, only green crackers were allowed in Delhi during an 8pm to 10pm window; the readings for October 26, 27 and 28 were 287, 337 and 368.
The subsequent years underline the gap between a legal order and implementation on the ground. A complete ban was imposed across the National Capital Region in 2020, but it was widely flouted. The readings for November 13, 14 and 15 were 339, 414 and 435. In 2021, a complete ban in Delhi was also flouted, while readings for November 3, 4 and 5 were 314, 382 and 462. In 2022, the reported readings for October 23, 24 and 25 were 259, 312 and 303, despite a complete ban that was flouted.
The same pattern continued in 2023 and 2024. Delhi imposed complete bans, but the restrictions were flouted. The reported readings were 220, 218 and 358 on November 11, 12 and 13 in 2023, and 307, 328 and 339 on October 30, 31 and November 1 in 2024. In 2025, green crackers were allowed during the 6am to 7am and 8pm to 10pm windows, but the restrictions were widely flouted. The readings for October 19, 20 and 21 were 296, 345 and 351.
This history shows that Delhi’s firecracker policy has moved between bans, limited windows and conditional permission, but the recurring enforcement problem has remained. The available figures do not by themselves isolate the contribution of fireworks from other sources of pollution, nor do they establish a direct causal relationship between a particular restriction and a particular reading. They do, however, show that legal controls have not consistently translated into compliance during the period when firecracker use is regulated.
The institutional design is therefore divided. CSIR-NEERI and PESO are linked to the certification and identification of green crackers. The Supreme Court sets the legal framework described in the report, including permitted time windows. Delhi’s enforcement challenge is operational: identifying compliant products, limiting sales or use outside the approved periods, and responding when a complete ban or restricted regime is ignored. The source material does not detail the agency-level enforcement mechanism, staffing or penalties involved.
For residents, the practical issue is exposure rather than the label alone. A green logo may indicate that a product is made to a specified formulation, but it does not mean zero emissions. The reported ultrafine-particle findings also indicate that the health question cannot be answered solely by comparing visible smoke or headline reductions in PM emissions. At the same time, the evidence supplied does not quantify the health risk from green crackers in Delhi or compare it with exposure from conventional fireworks over a full festival night.
The larger urban question is how Delhi should evaluate pollution controls that reduce harm without eliminating the source. Green crackers offer a measurable reduction in selected inputs and reported particulate emissions, but the city’s experience also shows that product standards and time restrictions depend on compliance. The difference between a laboratory or product-level target and an improvement in neighbourhood air quality is created by enforcement, usage volumes and local conditions—factors that remain incompletely established in the supplied evidence.
What the evidence confirms is narrower but significant: green crackers are engineered to emit less than conventional crackers, they exclude several chemicals used in conventional products, and they may still generate high concentrations of ultrafine particles. Delhi’s repeated restrictions have not prevented widespread flouting in the years described. The next measure of the policy will therefore not be the green label alone, but whether authorised products are used within the permitted windows and whether the resulting pollution readings and particle profile show a meaningful difference.
