Delhi air quality worsens ahead of Diwali as firework restrictions enter force

Delhi’s AQI reading of 377 means its air is classified as “very poor” under India’s pollution scale. Readings from 301 to 400 fall into this category. Anything above 400 is considered “severe.” The classification matters because it shows that pollution has reached a level requiring public-health concern and emergency action.

The AQI combines measurements of eight major pollutants, including PM2.5. On Wednesday morning, Delhi recorded 377. PM2.5 consists of extremely small particles that can travel deep into the lungs. The reading reflects the combined pollution burden rather than one pollutant alone.

Authorities responded by invoking Stage II of GRAP. Measures include more intensive road cleaning, higher parking charges and additional public transport. Forecasts suggested conditions would remain very poor, so the reading was not treated as a brief, isolated problem. Continued exposure can worsen respiratory illnesses and particularly threaten children and older people.

Stage II of the Graded Response Action Plan is a set of emergency measures used when pollution rises. GRAP becomes progressively stricter as air quality deteriorates. Its purpose is to reduce major pollution sources quickly and limit exposure while forecasts indicate that poor conditions may continue.

Delhi’s Stage II measures include more intensive road cleaning, higher parking charges and increased public transport services. Delhi Metro added 20 weekday train trips. Authorities were also directed to stagger government office timings, which should ease traffic congestion and reduce pressure from vehicle emissions.

The plan was introduced after Delhi’s AQI crossed 300 and forecasts suggested very poor air over the following days. It does not target only one source. Instead, it combines dust control, transport changes and traffic management. During more severe episodes, authorities may add hybrid schooling, work-from-home arrangements and restrictions on certain vehicles.

PM2.5 refers to fine particulate matter small enough to enter the respiratory system. The article compares these particles with a human hair: they are about 30 times smaller in width. Their scale makes them difficult to keep out of the body when people breathe polluted air.

Unlike larger dust particles, PM2.5 can travel deep into the lungs. The article does not give a precise anatomical depth, such as a distance in centimetres. It explains that the particles can penetrate deep into lung tissue, which is why they are a central concern in Delhi’s AQI measurement.

Delhi’s AQI includes PM2.5 among eight major pollutants. When the city’s AQI reached 377, residents were facing very poor air. Prolonged exposure can cause respiratory problems and worsen existing illnesses. Children and older people are particularly vulnerable, so high readings carry broad health implications.

Breathing Delhi’s polluted air over a prolonged period can cause respiratory problems. It can also worsen illnesses that people already have. The danger increases when pollution remains high for several days, because residents continue inhaling fine particles and other pollutants during ordinary activities.

PM2.5 is especially important because these particles are about 30 times smaller than the width of a human hair. They can penetrate deep into the lungs. Delhi’s AQI reached 377, placing the city in the “very poor” category, while the AQI measures PM2.5 and seven other major pollutants.

Children and older people are particularly vulnerable, according to the article. Authorities therefore introduced emergency measures under Stage II of GRAP, including extra Metro services and more road cleaning. During especially severe episodes, Delhi has also used hybrid schooling, work-from-home arrangements and restrictions on certain vehicles to reduce exposure and emissions.

Diwali fireworks worsen Delhi’s air because they release fine particles and harmful gases. These emissions are added to pollution already produced by vehicles, industry, dust and crop-residue burning. Fireworks are therefore a short, intense source that can push an already unhealthy atmosphere to even higher pollution levels.

Green firecrackers use modified chemical formulations designed to produce fewer emissions than conventional fireworks. They must carry QR codes showing manufacturer and certification details. However, “fewer” emissions does not mean no emissions. The Supreme Court allowed certified green crackers only during specified hours on 7 and 8 November, with bans near silence zones.

Enforcement remains difficult. The court acknowledged that conventional crackers had been sold as green alternatives even during a complete ban. Police were directed to patrol sales areas, check QR codes randomly and seize illegal fireworks. Last year, Delhi woke to toxic haze after Diwali despite restrictions.

Delhi’s air usually worsens in winter because several conditions work together. Temperatures fall, wind speeds slow and pollution from vehicles, industry and other sources disperses less effectively. The seasonal pattern becomes especially serious around Diwali, when fireworks add more particles and gases.

The article describes how a recent storm temporarily cleared the air with rain and stronger winds. When the weather settled, northwesterly winds returned. They carried smoke from crop-residue burning in Punjab and Haryana toward Delhi. Rising crop burning, combined with weak local dispersion, helped explain the sudden deterioration after an unusually clean October.

This pattern means Delhi’s pollution is not caused only inside the capital. Smoke from neighbouring states can add to local emissions when winds blow toward the city. Forecasts indicated very poor air would continue, prompting Stage II GRAP measures and concerns that Diwali fireworks could worsen conditions further.

Temperature, wind and rain influence whether pollutants spread out or remain concentrated. Stronger winds can move polluted air away from a city, while rain can help clear particles from the atmosphere. Low wind speeds do the opposite: they reduce dispersion, allowing emissions to accumulate near where people live and travel.

Delhi’s recent weather showed this mechanism clearly. A storm brought rain and stronger winds, helping clear the air. After the weather settled, northwesterly winds returned and carried smoke from burning fields toward the capital. Falling temperatures and slow winds then contributed to the city’s sharp deterioration after a clean October.

These conditions matter because pollution sources continue operating even when the weather changes. Vehicle exhaust, industrial emissions, dust, crop burning and fireworks can all add to the burden. If weak winds and low temperatures persist, air quality can remain very poor, as forecasts indicated for Delhi.