Aerosols.
Invisible, everywhere, and in every breath you take. Here's what they are — and why they matter.
What they are
An aerosol is a gas carrying tiny solid or liquid particles. Small enough to float. Small enough to breathe.
Liquid or solid.
Droplets — like mist, sprays or the water in clouds — and solid particles — like dust, soot or pollen — are both aerosols. Many real particles are a mix of both.
Primary or secondary.
Some particles are released directly, like sea salt or soot. Others form in the air itself, when gases react and condense into new particles.
Sources
Where aerosols come from.
Most of the particles in our air are natural. But the ones we make ourselves are often the smallest — and the ones that matter most for health.
Oceans
Breaking waves and bursting bubbles launch salt particles into the air. By mass, sea spray is one of the largest aerosol sources on the planet.
Deserts
Wind lifts mineral dust that travels across continents. Saharan dust regularly reaches Europe and helps fertilise the Amazon.
across the Atlantic
Volcanoes
Eruptions inject sulfur gases high into the atmosphere, where they form particles that reflect sunlight.
global cooling after Mount Pinatubo, 1991
Forests
Trees release compounds that turn into particles — the blue haze over forested hills. Plus pollen and fungal spores.
Wildfires
Smoke from large fires can stay aloft for weeks and cross oceans before it settles.
Traffic, heating & industry
Combustion produces ultrafine soot and gases that form new particles. This is what air-quality limits like PM2.5 are about.
Agriculture
Ammonia from fertiliser and livestock reacts in the air to form fine particles — a major source in rural regions.
Everyday life
Deodorant, hairspray, cooking, candles. Our homes are full of aerosols.
Medicine
Inhalers and nebulisers create aerosols on purpose — precisely sized droplets that carry active substances deep into the lung.
And you.
Breathing, speaking, singing, coughing — every one of them releases fine droplets from your airways. You're producing aerosols right now.
Size
Size decides everything.
Drag the slider to explore five orders of magnitude — and see where a particle of that size lands when you breathe it in.
Simplified. Deposition depends on breathing pattern, particle density and shape.
In the body
What happens when you inhale.
The respiratory tract is a natural particle filter. Each section catches a different size — which is exactly why size control is the key to inhaled medicine.
Nose and throat
Large particles can't follow the bends of the airway. They hit the walls early and are swallowed or cleared.
Windpipe and bronchi
Medium particles make it past the throat but settle in the larger airways.
Small airways and deep lung
The target window for most inhaled medicines. These particles travel deep and settle gently.
Mostly breathed out again
Too small to settle quickly, too large to diffuse fast — many leave with the next exhale.
Alveoli
Ultrafine particles move by diffusion and can reach the tiny air sacs where gas exchange happens.
generations of branching airways
alveoli in an adult lung
of surface for gas exchange
Climate
Every cloud begins with an aerosol.
Water vapour needs a surface to condense on. Without aerosol particles as seeds, clouds as we know them wouldn't form.
Seeds for clouds
Sea salt, sulfate and dust particles act as cloud condensation nuclei. More particles mean more, smaller droplets — and brighter clouds.
Mirrors in the sky
Particles scatter and absorb sunlight. Their overall effect cools the planet — and how much remains one of the big open questions in climate science.
Medicine
Breathing in, on purpose.
Inhaled medicine reaches the lung directly and acts fast. The devices have improved over time — but the core principles haven't moved much.
The first portable nebulisers turn liquid medicine into a mist.
The pressurised metered-dose inhaler arrives — the “puffer” most people know.
Dry powder inhalers deliver medicine without propellants, driven by the patient's breath.
Soft mist inhalers produce a slow, fine cloud that's easier to inhale.
Delivery designed from the molecule up. That's what we're building.
This is where we come in.
We combine chemistry and aerosol physics to control what happens between the molecule and the breath.