Is the air quality good in Santiago?

On December 16, 2025, at 8:00 PM PT, Santiago, Chile, is experiencing very poor air quality due to urban emissions and stagnant weather. The AQI is above 200, classified as very unhealthy, with PM2.5 concentrations dominating.

These conditions can severely impact everyone, causing respiratory distress, aggravated heart conditions, and reduced lung function, with heightened risks for children, the elderly, and those with vulnerabilities. Recommendations include avoiding outdoor activities, sealing homes, wearing masks outdoors, and using air purifiers to mitigate exposure.

Air quality is dynamic and, like the weather, can change frequently. Santiago ranked 5th among the most polluted cities in the world today, with nearby cities like Rancagua also affected. Click here for a real-time air quality map of Santiago.

While air quality in Santiago is typically moderate, today’s conditions are exceptionally severe, with PM2.5 levels reaching 31 times the WHO annual guideline of 5 µg/m³. By comparison, Santiago’s 2024 annual average PM2.5 concentration was 17.3 µg/m³, equivalent to an AQI of 65. This means today’s pollution levels are more than nine times higher than the city’s annual average, underscoring the unusual and alarming intensity of this pollution episode.

Santiago, Chile, ranked as the 5th most polluted major city on December 16, 2025, 8:00 PM PT. Source: IQAir.

When will the air quality improve in Santiago?

Hourly forecasts indicate that air quality in Santiago is expected to improve later today as winds strengthen and disperse pollutants.

Hourly air quality forecast for Santiago, Chile, on December 16, 2025. Source: IQAir.

Daily data over the past 30 days show conditions have generally been remained good to moderate, but today’s spike has reached alarming levels, marking an unusual and severe pollution episode.

Daily air quality forecast for Santiago, Chile, for the last 30 days. Source: IQAir.

Air quality map of Santiago, Chile, on December 16, 2025, 8:00 PM PT. Source: IQAir.

What is causing poor air quality in Santiago?

Air quality in Santiago, Chile has worsened sharply in the past few hours, due to a temporary build-up of fine particulate pollution (PM2.5) combined with poor atmospheric dispersion.

Santiago’s basin-like geography traps pollutants when winds are weak and temperature inversions form, preventing vertical mixing and leading to rapid accumulation of exhaust from vehicles, industrial emissions and other combustion sources (1).

These conditions have previously prompted environmental alerts and restrictions as authorities seek to protect public health during spikes in contamination.

How can I protect myself from poor air quality?

• Get a free air quality app for real-time air quality alerts and forecasts.
• Shut doors and windows and set the HVAC to recirculate mode.
• Contribute to your community’s outdoor air quality data.
• Stay indoors when air quality is poor; if you do need to go outdoors, wear a KN95/FFP2 mask.
• Run a high-performance air purifier to filter particles, gases, and other pollutants.