Sydney, Australia Air Quality & Smog

Dominant pollutants, when pollution and smog are worst, a notable historical episode, and the official monitoring agencies for Sydney, Australia — plus how to check the current reading. Sydney reports air quality on the Australian Air Quality Index — our full guide explains how that scale works and how it compares to the US AQI.

Dominant pollutants

PM2.5 (bushfire smoke), summer ozone.

Seasonal pattern: when smog is worst

Sydney's baseline air is clean, but it is acutely vulnerable to bushfire smoke and hazard-reduction burns, especially in spring and summer. Hot days drive ozone in the western suburbs, where the basin traps pollution against the Blue Mountains. Dust storms occasionally spike PM10.

A notable air-quality episode

During the 2019–20 "Black Summer" bushfires, smoke blanketed Sydney for weeks. AQI readings ran many times above the hazardous threshold, ranking Sydney among the most polluted cities on Earth on some days and prompting unprecedented health warnings.

The local index and who runs it

Sydney reports air quality using the Australian Air Quality Index, not the US AQI — so the same air can read as a different number than you may be used to. NSW publishes hourly readings and the AQI through its Air Quality network, with dedicated bushfire-smoke guidance during fire season.

• NSW Department of Climate Change, Energy, the Environment and Water (DCCEEW)

How to check air quality in Sydney

For the official live reading, the agency portals above are the canonical source. To understand what the numbers mean, start with our guide to the Australian Air Quality Index and the broader comparison of world air-quality indices. Smog Report puts glanceable air quality on your iPhone — widgets, Live Activities, Siri, and Apple Watch — free and with no account.

Common questions about Sydney air quality

Why does Sydney have air-quality and smog problems?

Sydney's baseline air is clean, but it is acutely vulnerable to bushfire smoke and hazard-reduction burns, especially in spring and summer. Hot days drive ozone in the western suburbs, where the basin traps pollution against the Blue Mountains. Dust storms occasionally spike PM10.

What are the main air pollutants in Sydney?

Sydney's dominant pollutants are PM2.5 (bushfire smoke), summer ozone. The reading on any given day is usually driven by whichever of these is highest.

Has Sydney had a major air-quality or smog event?

During the 2019–20 "Black Summer" bushfires, smoke blanketed Sydney for weeks. AQI readings ran many times above the hazardous threshold, ranking Sydney among the most polluted cities on Earth on some days and prompting unprecedented health warnings.

What air-quality index does Sydney use?

Sydney reports air quality on the Australian Air Quality Index (AQI), not the US AQI — so the same air can read as a different number than you may be used to. For live, glanceable readings on your iPhone, the free Smog Report app auto-selects the right local index for wherever you are.

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