Fine particles (PM1.0)
PM1.0 is the finest fraction of airborne particulate matter — particles under one micron. Because they are so small, they penetrate deepest into the lungs and can cross into the bloodstream. They come from combustion, cooking and outdoor pollution, and are largely invisible.
The smallest particles, the deepest reach.
PM1.0 matters precisely because of its size — small enough to evade the body’s defences and reach the bloodstream.
Deepest penetration
Sub-micron particles reach the alveoli and can enter the blood, linked to cardiovascular as well as respiratory effects.
Combustion marker
PM1.0 is dominated by combustion — traffic, cooking, smoke — making it a sensitive indicator of those sources.
Beyond PM2.5
Measuring PM1.0 separately reveals fine-particle pollution that coarser metrics can under-represent.
Filtration check
Tracking PM1.0 shows how well filtration and ventilation remove the hardest-to-catch particles.
Keep the finest particles low.
There is no separate WHO limit for PM1.0, so it is read against the same low targets as fine particulate matter — the lower, the better.
Mostly combustion, indoors and out.
The finest particles are produced by burning — so cooking, smoke and traffic dominate, alongside infiltrating outdoor air.
Cooking & frying
High-heat cooking, especially frying, is a leading indoor source of sub-micron particles.
Smoke & candles
Tobacco smoke, candles and incense produce large numbers of very fine particles.
Outdoor pollution
Traffic and combustion outdoors generate PM1.0 that infiltrates through windows, doors and ventilation.
Printers & equipment
Laser printers and some machinery emit ultrafine particles during operation.