Delhi AQI hits 462 as severe smog forces schools to adopt hybrid mode

Even as the authorities invoked stringent restrictions under Stage-IV and the Graded Response Action Plan (GRAP) on Saturday, the Delhi Directorate of Education directed all schools to conduct classes for students up to Class IX and XI in a hybrid mode in light of the deteriorating air quality in the national capital. This comes after hybrid classes were ordered for children up to Class V and additionally, a ban on construction and demolition activities.

Unfavourable meteorological conditions, combined with vehicle emissions, paddy-straw burning, firecrackers and other local pollution sources, are leading to hazardous air quality levels in Delhi-NCR during winters.

Work-from-home

On Saturday, the Commission for Air Quality Management (CAQM) invoked Stage-IV actions under GRAP with immediate effect to curb further worsening of air pollution levels in Delhi-NCR.

According to the circular dated December 13, government, government-aided, and unaided recognised private schools under the Directorate of Education, NDMC, MCD, and the Delhi Cantonment Board have been instructed to offer both physical and online classes wherever feasible until further orders.

Also read: Toxic smog blankets Delhi, AQI hits season's worst at 431

In an official order, the government directed that all administrative secretaries and heads of departments shall attend office regularly, with no more than 50 per cent staff strength physically present. "The remaining 50 per cent staff shall work from home, provided that the administrative secretaries and heads of departments can call officers/officials to the office, as required to ensure uninterrupted delivery of essential and emergency public services," the order read.

Likewise, the order stipulated that all private offices operating within Delhi shall function with no more than 50 per cent staff physically attending the workplace. "The remaining staff shall mandatorily work from home," it added.

The order also urged all private entities to implement staggered working hours where feasible.

Furthermore, private offices have been instructed to ensure strict compliance with work-from-home norms and minimise vehicular movement related to office commutes.

"Hospitals and other public/private health establishments, Fire Services, Prisons, Public Transport, Electricity, Water, Sanitation and related municipal services, disaster management and related services, forest and environment departments/agencies engaged in air pollution control, monitoring, and enforcement activities (like teams deployed to curb biomass burning, dust control, GRAP measures, etc.), and other essential/emergency services shall be exempted from these directions," the order said.

'Red' alerts

On Sunday, all 40 monitoring stations across the capital registered ‘red’ alerts, indicating hazardous conditions. Rohini in North West Delhi topped the charts with an AQI of 499, driven primarily by PM2.5 levels. Jahangirpuri and Vivek Vihar followed closely, each recording 495.

Also read: Delhi wakes up to thick smog as air quality nears 'severe' mark

Smog also reduced visibility in several parts of the city. In Patparganj, East Delhi, where AQI stood at 488, commuters were seen driving cautiously with headlights switched on.

The Air Quality Index (AQI) is a public health tool that indicates how clean or polluted the air is. It is calculated using eight key pollutants: particulate matter (PM10 and PM2.5), ozone (O₃), sulphur dioxide (SO₂), nitrogen dioxide (NO₂), carbon monoxide (CO), lead (Pb), and ammonia (NH₃), as defined by the Central Pollution Control Board (CPCB).

The CPCB classifies AQI into six categories:

• 0–50: Good – Air quality poses little or no risk.
• 51–100: Satisfactory – Acceptable, though minor health concerns may arise for sensitive groups.
• 101–200: Moderate – Breathing discomfort possible for vulnerable individuals.
• 201–300: Poor – Prolonged exposure may cause health issues.
• 301–400: Very Poor – Respiratory illness likely on extended exposure.
• 401–500: Severe – Hazardous for everyone; outdoor activity should be avoided.

An AQI in the ‘severe’ range is dangerous even for healthy individuals, making it advisable to stay indoors and refrain from physical exertion outside.

Sharp rise in pollution

On Saturday, the Sub-Committee on GRAP had earlier in the day decided to invoke Stage III of GRAP across the entire NCR with immediate effect as air quality continued to worsen.

However, noting a further sharp rise in pollution levels since morning, the sub-committee held an urgent meeting at 6.30 pm to review the situation and weather forecasts by the IMD and IITM.

It observed that Delhi's AQI, which stood at 401 at 10 am in the "severe" category, continued to rise steadily due to very low wind speed, a stable atmosphere and unfavourable weather conditions that prevented dispersion of pollutants.

The AQI climbed to 431 at 4 pm, 436 at 5 pm, 441 at 6 pm and 448 at 7 pm, the panel said.

It said these conditions, along with calm winds and mist or haze during the night, are likely to persist, further trapping pollutants over the region. This is in addition to the actions under Stages I, II and III of GRAP already in force in NCR, the statement added.

Stage IV restrictions

Stage IV of GRAP brings the strictest restrictions in Delhi-NCR.

Under this stage, the entry of trucks into Delhi is stopped, except those carrying essential commodities or providing essential services. However, CNG, LNG, electric and BS-VI diesel trucks are allowed.

The plying of Delhi-registered diesel heavy goods vehicles (BS-IV and below) is banned, again with exceptions only for essential services.

All construction and demolition activities are banned as well, including even linear public projects such as highways, roads, flyovers, power transmission lines, pipelines and telecom works, which are otherwise allowed in lower stages.

Under Stage IV, state governments are asked to consider additional emergency steps, such as closing colleges and educational institutions, shutting non-essential commercial activities and even introducing odd-even rules for vehicles if the pollution situation worsens further.

Explaining the reasons for the worsening AQI, the CAQM said the feeble Western Disturbance approaching north-west India was the main contributing factor, and not local emissions.

"This prevailing meteorological condition has (caused a) marked reduction in wind speed, at times becoming calm, a shift in wind direction from westerly to easterly, and an increase in moisture content in the lower atmosphere. Such conditions during the winter season are conducive to the formation of smog and fog, resulting in poor dispersion and trapping of pollutants near the surface. Owing to these adverse meteorological conditions, a sudden deterioration in air quality has been observed," it said.