Uncertainty Budget of the SMPS–APS System in the Measurement of PM₁, PM_2.5, and PM₁₀

Figures & data

FIG. 1 Average particle size distribution referred to the 5–10 September 2008 period.

FIG. 2 Average mass concentration distribution referred to the 5–10 September 2008 period.

FIG. 3 PM uncertainty trends determined using the SMPS-APS.

FIG. 4 PM₁₀ and PM₁ uncertainties of the SMPS-APS system as the mass measured by the APS varies.

TABLE 1 SMPS uncertainty contribution in the PM_2.5 measurement referred to the 5–10 September 2008 period

	Uncertainty value	Distribution	Uncertainty contribution um − SMPS,i(xi) (μg m^−3)
Raw count (c')		Poisson	1.09·10^−1
Sampling flow rate* (θ)	±0.015 L min^−1	Normal	3.94·10^−1
Diffusion efficiency correction (ηdiff)	±10%		1.26·10^−1
CPC efficiency correction (ηCPC)	±8%;	Rectangular	1.01·10^−1
DMA efficiency correction (ηDMA)	Included in volumetric diameter uncertainty
Sampling time* (t)		Negligible
Particle density* (ρp)	±0.5 g cm^−3	Rectangular	2.68
Volumetric diameter (dve)	±0.95%	Rectangular	2.46·10^−2
Flow ratio (φ)		Negligible
()			2.72
Statistical cover factor k			2
()			5.43
()			15.8
Relative uncertainty			34.4%

* Fully correlated contributions.

TABLE 2 APS uncertainty contribution in the PM_2.5 measurement referred to the 5–10 September 2008 period

	Uncertainty value	Distribution	Uncertainty contribution um − APS,i (xi) (μg m^−3)
Raw count (c')	(	Poisson	7.24·10^−2
Aerosol flow rate* (θaerosol)	±10%;	Normal	4.59·10^−1
APS efficiency (η)	±10%;	Rectangular	8.36·10^−2
Sampling time* (t)		Negligible
Particle density* (ρp)	±0.5 g cm^−3	Rectangular	1.56
Volumetric diameter (dve)	Uncertainty combination of Cc(dae), Cc(dve), χ, ρp, and ρ0 uncertainties		3.96·10^−1
(			1.67
Statistical cover factor k			2
(			3.35
(			9.17
Relative uncertainty			36.5%

*

Fully correlated contributions.

FIG. 5 SMPS-APS system and gravimetric method comparison in measuring PM₁₀, PM_2.5, and PM₁.