AQI Explained

Ground-level ozone forms in sunlight, peaks in the afternoon and can push AQI up on clear days. What it is, safe limits and how to protect yourself.

PM2.5 and PM10 aren’t interchangeable. Here’s what actually separates them, why size determines health risk, and how India’s air quality limits compare to WHO guidelines.

Delhi’s AQI hit 166 on October 1, its worst start to October since 2022. Here’s what the numbers show, what changed in this year’s GRAP, and how to prepare.

Why does air get dirtier on calm days even when emissions haven’t changed? The ventilation index explains it in plain language.

Haze from Kalimantan fires reached Manila on October 4. Here’s why peat fires are so harmful, what El Niño has to do with it, and how to protect yourself.

IMD expects scattered showers over Delhi, Punjab and Haryana on October 6-8. Here’s what light rain really does to smog, and why the relief is usually short-lived.

One app says 100, another says 155. Neither is broken. Here’s why AQI numbers differ by scale, sensor, location and timing, and which one to trust.

The monsoon withdrew from Delhi on 23 Sept 2026, its earliest exit since 2002. AQI climbed from 118 to 178 in days. Here’s what it means for your air.

CAQM logged 84 farm fires in Punjab in one early-October day, 30 confirmed. Here’s how that compares with last year and what it means for Delhi’s AQI.

A plain-English guide to temperature inversions: how a layer of warm air traps pollution near the ground, when it happens, and how to plan around it.

Delhi’s September 2026 AQI averaged 102, a five-year low, yet a separate analysis shows the year so far is worse. Here’s how both can be true and what to expect in October.

A plain-English guide to smog masks: why a sealed N95-type respirator beats cloth and surgical masks, how to check the fit, and when to wear one.

India’s 2026 monsoon ended 13% below normal and IMD expects a dry, warm October. Here’s what that could mean for smog season, in plain language.

What SO2 is, how it affects your lungs, how it becomes PM2.5, and why India is debating scrubbers on coal power plants after the 2025 rule change.

WMO’s September 2026 bulletin says wildfire smoke and heat-driven ozone are undoing clean-air progress. Here’s what it means and how to protect yourself.

A plain-English look at how India’s air quality stations measure pollution, where low-cost sensors fit in, and why readings differ across a city.

Indonesia’s ISPU and India’s AQI use different tiers, so ‘Moderate’ and ‘Unhealthy’ don’t mean the same thing. Here’s how to translate haze readings between the two scales.

CAQM’s Statutory Direction No. 98 sets a uniform 50 mg/Nm³ particulate emission limit for Delhi-NCR industries, fully in force from October 1, 2026. Here’s who it covers and why it matters.

Farm fires are up about fivefold in Madhya Pradesh and have tripled in Rajasthan, while Punjab, Haryana and UP decline. Here’s what the Centre’s mission-mode push means for winter air.

Minnesota’s air quality alert on October 10 wasn’t about smoke. Dry soil and strong gusts lifted coarse PM10 dust. Here’s how it works and what to do.