Delhi AQI after Diwali 2026: the smoke peaked after midnight and was still Hazardous at dawn

Delhi's Diwali smoke peaked after midnight. Across the Delhi monitors still reporting, the median US AQI reached 1,398 around 12:30 am on 9 November 2026, up from 292 at 7:30 pm, before the 8 to 10 pm green-cracker window. By 7:30 am it had eased to 466, still Hazardous, with 25 of 37 reporting Delhi monitors above 300. That is our analysis of hourly readings from 65 CPCB monitors across Delhi NCR. The official 24-hour figure for the day after Diwali comes in CPCB's 4 pm bulletin today; we will add it here.

What happened overnight, hour by hour

Good Air shows the US AQI first, the same scale as the Good Air app, with India's official National AQI (NAQI) beside it where it matters. The figures in this section are US AQI from single hours at each monitor; CPCB's bulletin figures further down are NAQI and are labelled.

Medians are across the Delhi monitors reporting each hour. The hourly series has no point for 11:30 pm.

Three things stand out:

• The rise started before the legal window. The median was already 292 at 7:30 pm and 548 at 8:30 pm, an hour into the 8 to 10 pm window the Supreme Court allowed for green crackers. It kept climbing for two to three hours after the window closed.
• The worst came around midnight. This matches what our hourly data shows on ordinary winter nights: the air near the ground is coldest and stillest after midnight, so smoke stays low (why Delhi's air is worst at night).
• Many monitors went quiet at the worst time. 43 Delhi monitors reported at 7:30 pm but only 14 at 1:30 am. The median for the small hours rests on fewer monitors, so treat it as a guide, not a city average. Eight Delhi monitors reported every hour from 7:30 pm to 7:30 am; their median followed the same shape, from 235 at 7:30 pm to 862 at 12:30 am and 356 at 7:30 am.

The worst monitors

Across Delhi NCR, 56 of the 59 monitors that reported overnight passed US AQI 500 in at least one hour between 7:30 pm and 7:30 am. Some stayed there most of the night.

• Longest: DTU was above 500 for 10 of the 12 hours it reported, and Punjabi Bagh for all 10 it reported. Aya Nagar followed with 9, then Chhawla, Pusa, IGI Airport T3 and Sector 62 in Noida with 8 each.
• Highest single hours: ITO 1,844 at 5:30 am, North Campus 1,842 at 9:30 pm, Lodhi Road 1,837 at 1:30 am and Punjabi Bagh 1,830 at 2:30 am. Outside Delhi, Khora hit 1,769 at 8:30 pm and Sector 110 in Noida 1,771 at 12:30 am.
• At the top of the scale: those peaks sit at PM2.5 of about 960 to 1,000 µg/m³. ITO's 5:30 am reading is exactly 1,000, a common upper limit for the instruments at these stations, so the true value may have been higher. Read these as "at least".

Around the NCR

The smoke peaked earlier outside Delhi. Ghaziabad's six monitors had a median of 1,118 at 10:30 pm and Noida's 978 at the same hour, while Delhi's peak came about two hours later. By 7:30 am the satellite cities had cleared faster than Delhi:

Gurugram and Noida had only one to five monitors reporting each hour, so their figures are less certain than Delhi's. Live readings for every area are on the Delhi, Noida, Ghaziabad and Gurugram pages.

Why the morning numbers differ so much

On the morning after Diwali, CPCB's Sameer app showed Delhi at 368 (Very Poor) at 7:05 am, while a private app showed 1,039 at 6:31 am (ETV Bharat, 9 November). Both can be right:

• Sameer shows India's NAQI averaged over 24 hours. At 7 am that average still includes the cleaner afternoon of 8 November, and the NAQI scale stops at 500.
• US AQI from a single hour has no cap and no averaging. One smoky hour shows in full. Our 7:30 am Delhi median of 466 is the same kind of number.
• Which monitors you average matters. A city figure built from the worst few stations will read higher than one built from all of them.

More in why AQI apps show different numbers and US AQI vs India's NAQI.

How this Diwali compares (India NAQI)

CPCB's 4 pm bulletin, which averages the past 24 hours on India's NAQI, put Delhi at 376 (Very Poor) on Diwali day, up from 369 on 7 November (CPCB, 8 November). Of the eight Diwalis from 2018 to 2025, only 2020 (414) and 2021 (382) started worse.

The day after has been worse than Diwali day in seven of those eight years. The exception was 2022.

Source: CPCB daily AQI bulletins.

What to watch at 4 pm: a 24-hour figure above 400 would make 9 November Delhi's first Severe day of the season. GRAP Stage III has applied since 6 November; Stage IV applies when the 24-hour NAQI is above 450 (what each stage does). As of 9 November morning, Stage III was still the stage in force (ETV Bharat). The Supreme Court's full cracker ban in Delhi NCR returns today (Courtbook, 2 November).

What to do today

• Keep windows shut through the morning and run a HEPA purifier if you have one. Early afternoon is usually the cleanest time of day to air the house or go out.
• Wear a well-fitted N95 or FFP2 mask outdoors; cloth masks do little against fine smoke.
• People with asthma, heart disease, older adults and young children should avoid hard exercise outside today. More in our Diwali health guide.
• Check the monitor nearest you: at 7:30 am Delhi's monitors ranged from US AQI 193 to 1,637 in the same hour.

How we measured

We took every hourly reading from CPCB's continuous monitors inside the Delhi NCR box (89 monitors listed, 65 with readings) from 12:30 pm on 8 November to 7:30 am on 9 November, through the same feed that powers our live area pages. PM2.5 is the hourly concentration; US AQI is worked out from it on the US EPA's 2024 scale, and NAQI on India's. Medians are across the monitors reporting in each hour, which varied from 14 to 43 in Delhi. Readings were not filtered, apart from noting the 1,000 µg/m³ instrument limit. The hourly series has no point for 11:30 pm.

To watch every monitor hour by hour, play the Diwali 2026 pollution map. Live updates through the night are on our Diwali AQI tracker and the season on the Delhi air pollution tracker.