IAQ Simulator — EDIAQI Indoor Air Quality Prediction

What this tool tells you

what PM2.5 and CO₂ are, and why they matter

Describe a building and where it is, and this simulator estimates the air quality inside it right now — without you needing a sensor. It works in two steps: first it estimates the outdoor air at your address from satellite forecasts, nearby monitoring stations and the surrounding land use; then it works out how much of that outdoor air gets in, and what the activities inside add on top.

It reports two numbers. Here is what they are and why they matter.

Fine particles (PM2.5) µg/m³

Airborne specks smaller than 2.5 micrometres — about 1/30th the width of a human hair. They come from traffic, wood and coal burning, cooking, candles and cigarettes. Being so small, they slip past the nose and throat and reach deep into the lungs, and the smallest cross into the bloodstream.

Why it matters: PM2.5 is the air pollutant most firmly linked to ill health. Short term it irritates airways and can trigger asthma and heart symptoms; over years it raises the risk of heart disease, stroke, lung disease and lung cancer. The WHO puts the long-term guideline at just 5 µg/m³. There is no level known to be completely safe, so lower is always better.

Carbon dioxide (CO₂) ppm

The gas everyone breathes out. Outdoor air sits at roughly 420 parts per million; indoors it climbs whenever people are present and the room is not getting enough fresh air. That makes it an excellent stand-in for ventilation: high CO₂ means the air in the room is largely air that has already been breathed.

Why it matters: CO₂ is not toxic at indoor levels, but above roughly 1000 ppm people report stuffiness and headaches, and studies find measurable drops in concentration and decision-making. It also warns you indirectly: poor ventilation lets everything else build up too — particles, chemicals from furnishings, and airborne viruses.

Why particles are in µg/m³ and CO₂ is in ppm. They are different kinds of measurement, so they cannot share a unit. ppm (parts per million) counts molecules of a gas among a million molecules of air — it works for gases like CO₂ and CO, which mix evenly into air. PM2.5 is not a gas: it is countless solid and liquid specks of many different substances, so there is nothing to count molecules of. Instead we weigh them — µg/m³ is the mass in micrograms of all the particles floating in one cubic metre of air. For a sense of scale: 10 µg/m³ is roughly a grain of salt's worth of dust spread through the air of a small bedroom.

Where would you like to check the indoor air quality?

The address sets the outdoor air the model starts from, so a street address gives a better result than a city name alone.

Street address

Include the street and number. The address is looked up with OpenStreetMap, and the exact point it resolved to is shown with your results so you can check it landed where you meant. If the lookup fails, the model falls back to the city centre and tells you so.

City

Pilot cities are where EDIAQI runs measurement campaigns. The indoor equations at the heart of this tool were calibrated on the Ferrara sensor network, and pilot cities are where local measurements are being folded back in — so results there carry the most confidence.

The other cities work too: outdoor air comes from Europe-wide feeds that cover any address on the continent. If you pick Somewhere else in Europe, write the full address including the country, because there is no country hint to narrow the search — and check the resolved coordinates shown with your results.

What is the area around the building like?

What this changes. This setting describes how sheltered the building is from wind — a tower on an open hillside is scoured by wind, a flat in a dense city block is shielded by everything around it. Wind pressure drives air through gaps in the envelope, so a more exposed building exchanges air faster. Expect it to move CO₂ noticeably, and PM2.5 whenever an indoor source is active.

What it does not change. It does not set your outdoor pollution level — that comes from the address itself, via nearby monitoring stations and the actual mapped land use around it. So picking "High traffic" will not manufacture dirty outdoor air if the model can see that your street is quiet.

What kind of building is it?

These set how airtight the envelope is and how much air the space holds.

Building type

Year it was built

Don't know exactly? An approximate decade is fine. Construction era is the single best available clue to how leaky a building is: standards tightened steadily, so a pre-1960 building typically leaks around five times as much as a post-2015 one. If you are unsure, the deeds, the local land registry, or simply the style of the surrounding street will get you close enough.

Floor area of the room or flat (m²)

Which floor?

Enter the space the air actually mixes in. For an open-plan flat with the internal doors open, that is the whole flat; for a closed bedroom or a single office, just that room. The model assumes a 2.5 m ceiling, so 75 m² becomes about 188 m³ of air. A smaller volume means the same amount of pollution is concentrated in less air, so it reads higher.

Height matters twice over. Warm indoor air rising up a tall building pulls outside air in at the bottom — the "stack effect" — so upper floors exchange air differently from the ground floor. Height also lifts you away from street-level traffic emissions, which is why higher floors tend to read slightly lower for particles.

How is the space ventilated and used?

Ventilation is the single biggest lever on your result — it decides how fast pollution leaves the room, and how much comes in from outside.

How does fresh air get in?

Window glazing

Natural — no fans. Air arrives through openable windows, trickle vents in the frames, and gaps in the structure. Most older homes.
Mechanical — a system that moves air deliberately: whole-house ventilation with heat recovery (MVHR), or an HVAC system in an office. Usually a unit in a utility cupboard or a plant room, and continuous ceiling or wall grilles.
Mixed (hybrid) — a building that switches between the two, using fans when conditions demand it and open windows when they suit. Common in newer schools and offices: the fans handle winter and hot still days, windows do the rest. If your building has fans but people also routinely open windows, choose this.
None — a sealed space with no purpose-built ventilation at all; air only leaks in through the envelope. Rare in occupied buildings, and it is the setting that produces the highest CO₂.

Glazing is used here as a proxy for how well sealed the window openings are: replacing windows usually means new frames and seals too. Triple glazing tends to accompany the tightest construction, single glazing the leakiest. A tighter building keeps outdoor pollution out — but also keeps indoor pollution in, which is why tight buildings need deliberate ventilation.

How many people are usually in the space? 3

This drives the CO₂ result almost entirely: people are the only meaningful indoor source of CO₂. Count the people present at the same time, not over a day. Two people in a bedroom overnight and thirty in a classroom are very different ventilation problems.

Indoor temperature (°C) 22

Don't know it? 20–22 °C is a safe answer for a heated home or office, and the result barely moves for a degree or two either way.

If you want to be precise: the thermostat or smart-meter display shows it, most heating apps log it, and any indoor thermometer will do. Only the temperature difference between inside and outside matters here — warm air rising indoors pulls cold air in through gaps, so on a cold day a warm room exchanges air faster. Today's outdoor temperature is fetched automatically for your address.

What happens inside the space?

Tap everything that is going on. These are the indoor sources of particles — and in most homes they matter more than the outdoor air does.

🍳 Cooking / gas stove 🚬 Smoking 🧹 Cleaning products 🕯️ Candles / incense 🐾 Pets 🖨️ Printers 🎨 Fresh paint 🪑 New furniture

🪟 A window is open 🏃 People are exercising

Every source you tick is itemised in the results, so you can see exactly how much each one contributes and decide which is worth doing something about.

Which set of equations should we use?

Leave this alone unless you are comparing model variants.

Equation variant

Data-driven uses the coefficients exactly as fitted to the 36-sensor EDIAQI deployment in Ferrara. It reproduces what was measured there.

Hybrid replaces the ventilation coefficients with values from the published literature. In the Ferrara data those coefficients came out with a sign that contradicts the physics — more ventilation appeared to raise indoor pollution, which happens when people open windows because the air is already bad. The hybrid variant corrects for that, at the cost of no longer being a pure fit to the data.

Expert settings — set the air exchange rates yourself

By default the model derives air exchange from the building description. If you have measured or commissioned values — from a blower-door test, ventilation commissioning documents, or a tracer-gas or CO₂ decay measurement — enter them here and they replace the estimate outright. Tick a box to take control of that term.

Your estimated indoor air quality

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Describe your building on the left, then press Estimate indoor air quality.
Your results, and what they mean for your health, appear here.

Run an estimate to see how much of the outdoor air makes it inside your building.

Run an estimate to see which indoor activities are adding to what you breathe, and by how much.

Run an estimate to see the air-exchange physics and per-pollutant workings behind the numbers.

Every abbreviation and piece of jargon this tool uses, in plain words.

How to read these numbers. They are a model estimate, not a measurement. Indoor concentrations combine a physics model of how air moves through your building (Sherman–Grimsrud infiltration) with equations calibrated on the EDIAQI sensor network in Ferrara, Italy; the outdoor air feeding them comes from machine-learning models built on the CAMS atmospheric forecast, land use around your address, and nearby public monitoring stations. Expect the estimate to capture the right level and the right direction of change, not the exact figure a sensor in your room would show. Carbon monoxide, NO₂ and ozone are modelled internally but not reported, because the validation behind them is not yet strong enough to publish. This tool is under active development as part of the EDIAQI project.