Smaller than the diameter of human hair
This is 1 μg/m³ of fine particulate matter per cubic meter of air. PM2.5 are particles 2.5 micrometers or smaller, less than 30th of a diameter of human hair.
Global annual safety limit
The World Health Organization has set the safe limit at 5 μg/m³. That's all the particulate exposure considered safe for a human body over an entire year of breathing.
The year's reality
Baguio's first year of real-time monitoring averaged 14.4 μg/m³. While the government labels this air 'Good,' it is nearly triple the limit where scientists say the air is safe to breathe.
New Year's Day 2026
PM2.5 exploded to unhealthy 73.23 μg/m³ — nearly 5x the daily WHO limit of 15 μg/m³. Fireworks, exhaust, and mountain air trapped in the city.
Peak months
In April and December, as tourists flock to Baguio, the average air quality masks dangerous spikes that cross into what the Philippines' calls "unhealthy" territory which is at least 2.3x the WHO daily guideline.