🗺️ Where does our PM2.5 come from?

Fires (change every day)

🔥 Fires seen by satelliteEach dot is a fire area. A bigger dot means more fire power. 🟫 PeatlandPeat is wet, dead plant material. When it dries and burns, it makes a lot of smoke for a long time.

Background: always there

🏙️ All human emissionsAll the PM2.5 that people put into the air in a year. 🚢 ShipsThousands of ships use the sea lanes near Singapore. Their exhaust makes particles. 🚗 Road trafficCars, buses, lorries and motorcycles. 🏭 Power stations and industryPower plants, refineries and factories. 🏠 Homes and farmsCooking with wood or charcoal, crop burning and farming. No emissions layerThe map shows no emissions.

0.050.5550 t per km² per year

The air and our box

💨 Path of the air (smoke level)Where the air was in the 4 days before it reaches Singapore, about 800 m up. Smoke travels at this height. 🌊 Path of the air near the seaThe same at 100 m. Ship exhaust stays low, so the model uses this path for ships. 📦 Our boxThe model treats the air over Singapore as one box, about 56 km long.

Path for:

The PM2.5 in Singapore comes from many sources. Fires in Sumatra and Borneo make the big haze days. Ships, traffic, power stations, industry, homes and farms are always there. They make the background: the PM2.5 that the air brings on a normal day. Turn the layers on and off to see them.

📦 The box over Singapore, seen from the side

The model does not follow every particle. It follows one number: the PM2.5 in a box of air over Singapore. The box goes from the ground up to a lid. The lid is a warm layer of air: a temperature inversion. The lid goes down at night and up in the day. Press Play the day and look at the lid, the dots (particles) and the temperature line on the right.

Why is the PM2.5 often higher at night? The same pollution goes into a box that is 3 to 5 times thinner, so each cubic metre gets more particles. This is concentration = mass ÷ volume. Lid heights: forecast from the month-and-hour average of 2014–2025 (ERA5). Temperature line: a sketch of a typical day, not a measurement. Learn more about the lid.

🌏 How much comes from each source?

In our air this week (model)

PM2.5 in Singapore by source, day mean, in µg/m³. On a clear day, the background, ships and our own emissions give about 10 to 15 µg/m³. Smoke from fires adds the rest.

What people put into the air in a year

Primary PM2.5 emissions on this map (EDGAR 2022). The map area is about 2,800 km by 1,800 km. "Near Singapore" is an area of about 55 km by 67 km around Singapore, with the port and the sea lanes.

Fires are not in this table. Fire smoke changes very much from day to day and from year to year. In a bad haze year, the fires make more smoke in a few weeks than all the sources in this table make in a year.

🌏 What is the background? Even with no fires, the air that comes to Singapore brings some PM2.5: sea salt, dust, and old pollution from the cities, industry, farms and ships of the whole region (the coloured layers on the map). The model gives it one number: about 8 µg/m³. It changes only a little with the path of the air.