What do the three particulate matter readings PM₁₀, PM₂.₅, and PM₁ mean?

The particulate matter reading PM₁₀  captures particles up to 10 µm in size; PM₂.₅ captures particles with a diameter of up to 2.5 µm, and PM₁ captures particles up to 1 µm in size. The PM₁₀ reading also includes the PM₂.₅ and PM₁ readings, and the PM₂.₅ reading also includes PM₁. For readings measured in µg/m³ or in particle count, it therefore holds that PM₁₀  > PM₂.₅ > PM₁.