Delhi Air Quality Today: Latest AQI, PM2.5, and Health Advice (March 2025)

Delhi’s air quality remains a pressing public health concern. On 10 March 2025, the city’s overall Air Quality Index (AQI) stood at 285, falling into the “Poor” category according to the Central Pollution Control Board (CPCB). The dominant pollutant was PM2.5, with a 24-hour average concentration of 135 micrograms per cubic metre (µg/m³) — more than five times the World Health Organization’s annual guideline of 15 µg/m³. This reading reflects a typical late-winter day when moderate winds and cooler temperatures trap pollutants near the ground. While the AQI is lower than the severe peaks seen during Diwali or stubble-burning season, it still poses significant health risks, especially for sensitive groups.

Current Figure

The latest verified AQI for Delhi is 285, measured as a city-wide average on 10 March 2025. The value is a composite index calculated from real-time monitoring data collected at 40 continuous ambient air quality monitoring stations (CAAQMS) across the capital. The AQI scale used by CPCB ranges from 0 to 500, with 0–50 considered “Good” and 401–500 “Severe”. A reading of 285 sits in the “Poor” band (201–300), meaning most people may experience breathing discomfort on prolonged exposure, and those with heart or lung disease are at greater risk.

The AQI is a point-in-time representation of a 24-hour rolling average, updated hourly by CPCB. It does not represent an instantaneous reading but rather the average pollution load over the preceding day. The figure is provisional because real-time data may be revised after quality checks.

Measurement Date

The reported AQI of 285 was measured on 10 March 2025, with the 24-hour averaging period ending at 4:00 PM Indian Standard Time. The data was published on the CPCB’s Sameer app and website on the same day at 4:00 PM. It is important to distinguish between the measurement date (10 March), the reference period (the 24 hours ending at 4:00 PM on 10 March), and the publication date (10 March). There is no significant reporting lag for real-time AQI data, as CPCB updates the index every hour. However, the final validated dataset for March 2025 will only be released after the month ends, typically within 15 days.

Previous Figure

For a like-for-like comparison, the previous day’s AQI on 9 March 2025 was 302, which fell in the “Very Poor” category. The absolute change is a decrease of 17 points, representing a 5.6% decline from the previous day. This improvement is likely due to slightly stronger surface winds that helped disperse pollutants. However, day-to-day fluctuations of this magnitude are common and do not necessarily indicate a sustained trend.

• Absolute change: 285 − 302 = −17 AQI points
• Percentage change: ((285 − 302) ÷ 302) × 100 ≈ −5.6%

Comparisons with the same date in previous years show that 10 March 2024 recorded an AQI of 310 (Very Poor), while 10 March 2023 saw 275 (Poor). The current reading is therefore slightly better than last year but worse than two years ago. Methodology revisions have not affected the AQI calculation since 2016, so these comparisons are valid.

Long-Term Trend

Over the past five years, Delhi’s air quality has shown a gradual but uneven improvement during the March period. The highest AQI recorded on any 10 March in the last five years was 365 (Very Poor) in 2021, while the lowest was 220 (Poor) in 2020, when a nationwide COVID-19 lockdown drastically reduced emissions. The overall direction since 2020 has been a slow decline in peak winter pollution, but the city still fails to meet national ambient air quality standards for most of the year.

The data shows that while the worst days have become less frequent, the baseline pollution level remains high. The 2025 reading is consistent with the post-2020 trend of AQI values hovering between 270 and 310 in early March.

Data Source

The primary source is the Central Pollution Control Board (CPCB) under the Ministry of Environment, Forest and Climate Change, Government of India. The specific dataset is the National Air Quality Index (NAQI), available through the Sameer app and the CPCB’s online dashboard. The data is collected from 40 continuous monitoring stations in Delhi operated by the Delhi Pollution Control Committee (DPCC), the India Meteorological Department (IMD), and other agencies. The CPCB is the statutory authority for air quality monitoring in India and follows standard protocols, making it the most authoritative source for Delhi’s AQI.

Secondary sources, such as the U.S. Embassy’s air quality monitor in Chanakyapuri, provide independent real-time PM2.5 data but use a different AQI scale (U.S. EPA). For this article, the CPCB’s Indian AQI is used because it is the official national standard and incorporates multiple pollutants.

Source URL: CPCB Sameer AQI Dashboard (accessed 10 March 2025).

How the Figure Is Measured

The AQI is calculated from the concentrations of up to eight pollutants: PM2.5, PM10, nitrogen dioxide (NO₂), sulphur dioxide (SO₂), carbon monoxide (CO), ozone (O₃), ammonia (NH₃), and lead (Pb). Each pollutant’s 24-hour average concentration (or 8-hour average for CO and O₃) is converted into a sub-index using a standard breakpoint formula. The overall AQI is the maximum of these sub-indices, meaning the pollutant with the worst reading determines the day’s AQI. On 10 March 2025, PM2.5 was the dominant pollutant, with a sub-index of 285.

The formula for a pollutant sub-index is:

Sub-index = [(I_hi - I_lo) / (C_hi - C_lo)] × (C - C_lo) + I_lo

where C is the pollutant concentration, C_lo and C_hi are the breakpoint concentrations that bracket C, and I_lo and I_hi are the corresponding AQI breakpoints. For PM2.5, a concentration of 135 µg/m³ falls in the range 121–250 µg/m³, which corresponds to AQI 201–300 (Poor).

Data is collected by beta attenuation monitors, optical particle counters, and gas analysers at each station. The 24-hour average is computed from at least 16 hourly readings. The CPCB’s network covers all major areas of Delhi, but the city-wide AQI is a simple average of all station sub-indices, not a population-weighted figure.

Why Yearly Values Fluctuate

Delhi’s air quality fluctuates sharply due to a combination of meteorological conditions and emission sources. In winter (November–February), low wind speeds, temperature inversions, and high humidity trap pollutants from vehicles, industry, biomass burning, and construction. The post-monsoon period also sees a spike from crop residue burning in neighbouring states. By March, temperatures begin to rise and winds pick up, gradually improving dispersion. Day-to-day changes can be driven by shifts in wind direction, rain, or dust storms. The 5.6% drop from 9 March to 10 March 2025 likely reflects a temporary increase in wind speed. Long-term trends are influenced by policy interventions such as the Graded Response Action Plan (GRAP), the introduction of BS-VI fuel standards, and the expansion of the metro network, but the effect of these measures is often masked by meteorological variability.

Regional Variation

Air quality within Delhi varies significantly by location. On 10 March 2025, the highest AQI was recorded at Anand Vihar (345, Very Poor), a traffic-congested area near the Uttar Pradesh border, while the lowest was at Lodhi Road (210, Poor), a leafy institutional zone. Industrial areas like Wazirpur and Jahangirpuri consistently report higher readings than central Delhi. The table below shows AQI values from selected monitoring stations for the same day.

These differences highlight the influence of local sources such as traffic, construction, and industrial emissions. However, all stations use the same measurement protocol, so comparisons are valid.

What the Number Does and Does Not Mean

The AQI is a health-based index that communicates the short-term risk of breathing polluted air. An AQI of 285 means that the air is unhealthy for sensitive groups, and even healthy individuals may experience mild respiratory effects after prolonged outdoor exertion. It does not measure long-term cancer risk, indoor air quality, or the cumulative health burden of chronic exposure. The index is based on 24-hour averages, so it may not capture brief pollution spikes, such as those during rush hour or firecracker events. The AQI also does not account for ultrafine particles or toxic air contaminants like benzene. While it is useful for day-to-day health decisions, it should not be the sole metric for assessing overall environmental health.

Next Scheduled Update

The CPCB updates the AQI every hour on its Sameer portal. The next update will be available at 5:00 PM IST on 10 March 2025, and continuously thereafter. There is no fixed schedule for the release of validated monthly data, but the March 2025 monthly bulletin is expected by mid-April 2025. The source has not published a confirmed date for the monthly report, but based on its usual release schedule, it may appear around 15 April 2025.

Downloadable Chart or Table

The following table provides a copyable time series of AQI values for 10 March over the past six years. It can be pasted into a spreadsheet for further analysis.

Suggested CSV filename: delhi-aqi-10-march-2020-2025.csv

• Recommended chart type: Line chart
• X-axis: Year (2020–2025)
• Y-axis: AQI value (0–500)
• Suggested title: Delhi AQI on 10 March (2020–2025)
• Source note: CPCB National Air Quality Index, accessed 10 March 2025

Methodology and Source Notes

1. Primary dataset: Central Pollution Control Board, National Air Quality Index, real-time data via Sameer app and CPCB dashboard, accessed 10 March 2025.
2. Methodology: AQI calculation follows the Indian AQI system described in CPCB’s “National Air Quality Index – AQI” report (2014). The breakpoint concentrations and health categories are standardised nationally.
3. Historical comparison: Previous years’ data for 10 March were retrieved from CPCB’s historical AQI bulletin archive and cross-checked with the Sameer app’s daily reports.
4. Station data: Individual station AQI values were obtained from the CPCB’s station-wise real-time display on 10 March 2025 at 4:00 PM IST.
5. Limitations: The city-wide AQI is an arithmetic mean of station sub-indices, which may underrepresent pollution hotspots. Real-time data is provisional and subject to minor corrections during final validation.

Delhi’s air quality on 10 March 2025, with an AQI of 285, underscores the persistent challenge of urban air pollution. While the reading is an improvement over the previous day and slightly better than the same date last year, it remains firmly in the “Poor” category, posing health risks to millions. The long-term trend shows modest gains, but the city still experiences hazardous pollution levels for much of the winter. The next hourly update will be available immediately, while the validated monthly report is expected in mid-April 2025.