Summary of PM_2.5 measurement artifacts associated with the Teledyne T640 PM Mass Monitor under controlled chamber experimental conditions using polydisperse ammonium sulfate aerosols and biomass smoke

Figures & data

Table 1. PM measurement methods.

Manufacturer	Model	Measurement Parameter	Measurement Principle	FRM/FEM	Time Resolution	Deployment^a
Integrated Filter-Based Samplers
Tisch Environmetal	Tisch-Wilbur	PM Mass	Gravimetric	FRM	1 Hr^b	CH, C1, C2, C3
Semi-Continuous Samplers
Teledyne API	T640	PM Mass	Light Scattering	FEM	1 min	CH, C1, C2, C3
Met One	BAM-1022	PM Mass	Beta Attenuation	FEM	1 Hr	C3

^aCH-Chapel Hill chamber 2018; C1-Missoula chamber April 2018; C2-Missoula chamber April 2019; C3-Missoula chamber April 2021.

^bPer 40 CFR Part 50 Appendix L, PM_2.5 FRM samples are collected over 24 hr sampling periods, for this study the sampling period was reduced to 1-hr.

Figure 1. (a) T640 and FRM PM_2.5 mass concentration averages and (b) Scatter plot with linear regression statistics of 1-Hr FRM versus T640 PM_2.5 mass concentration results from the 2018 Chapel Hill, NC ammonium sulfate aerosol chamber-based study.

Figure 2. T640 and FRM PM_2.5 mass concentration averages (1-Hr) from the (a) 2018 (b) 2019 and (c) 2021 Missoula FSL burn chamber studies.

Figure 3. Scatter plot with linear regression statistics of 1-Hr FRM versus T640 PM_2.5 mass concentration results from the Missoula chamber studies.

Figure 4. Scatter plot with (a) quadratic and (b) cubic regression statistics of 1-Hr FRM versus T640 PM_2.5 mass concentration results from the Missoula Chamber Studies.

Figure 5. (a) BAM-1022 and FRM PM_2.5 mass concentration averages and (b) scatter plot with linear regression statistics of 1-Hr FRM versus BAM-1022 PM_2.5 mass concentration results from the Missoula 2021 Chamber Studies.

Figure 6. Time series showing the magnitude and direction of the T640 measurement artifact, Δ_FRM from a) the 2018 Chapel Hill ammonium sulfate aerosol studies and b) the 2018, 2019, and 2021 Missoula FSL chamber burns. The chamber zeros performed at the beginning of each day were removed from the Chapel Hill data set.

Figure 7. Scatter plot with linear regression statistics of 1-Hr Δ_FRM versus FRM PM_2.5 mass concentration results from a) the 2018 Chapel Hill ammonium sulfate aerosol studies and b) the 2018, 2019, and 2021 Missoula FSL chamber burns.

Table 2. T640 Δ_FRM MLR analysis results from the 2018 Chapel Hill chamber runs.

Log Transformed MLR: FRM PM2.5; Temp; RH; MMAD – 2 outliers removed
	R^2		Sum of Squares	F Value	P>F
	0.883		18.3448	32.06	<0.0001
Source	N	DF	Type III Mean Square	F Value	P>F
FRM^a	22	1	16.7864	117.35	<0.0001
Temp.	22	1	0.0169	0.12	0.735
RH	22	1	0.0217	0.15	0.702
MMAD^b	22	1	1.4509	10.14	0.005
Parameter	Estimate		Standard Error	t Value	P> |t|
Intercept	1.9475		1.2943	1.50	0.151
FRM	0.9036		0.0834	10.83	<0.0001
Temp.	−0.0845		0.2457	−0.34	0.735
RH	0.0941		0.2418	0.39	0.702
MMAD	−4.3163		1.3553	−3.18	0.005

^aFRM=PM_2.5 mass concentration as measured by the FRM.

^bMMAD is the mass median aerodynamic diameter measured by the TSI model 3321 APS.

Significant variables in bold text.

Figure 8. Time series showing 1-Hr average a) BC concentrations and b) Δ_C during the 2018, 2019, and 2021 Missoula FSL chamber burns.

Table 3. T640 Δ_FRM MLR analysis results from the Missoula chamber burns.

MLR: ΔC; FRM PM2.5; BC; MCE
	R^2		Sum of Squares	F Value	P>F
	0.8499		1892002.693	104.20	<0.0001
Source	n	DF	Type III Mean Square	F Value	P>F
ΔC^a	98	1	626519.9986	172.52	<0.0001
FRM^b	98	1	449065.6853	123.66	<0.0001
MCE^c	98	1	182232.0352	50.18	<0.0001
ΔC*MCE^d	98	1	623867.0067	171.79	<0.0001
FRM*BC^e	98	1	176699.5257	48.66	<0.0001
Parameter	Estimate		Standard Error	t Value	P> |t|
Intercept	−3100.2114		439.7390	−7.05	<0.0001
ΔC	67.1932		5.1157	13.13	<0.0001
FRM	−0.3370		0.0303	−11.12	<0.0001
MCE	3267.1175		461.2084	7.08	<0.0001
ΔC*MCE	−72.0543		5.4974	−13.11	<0.0001
FRM*BC	0.0010		0.0001	6.98	<0.0001

^aΔ_C – difference in absorption between the UV (BC1–370 nm) and IR (BC6–880 nm) channels of the AE33

^bFRM=PM_2.5 mass concentration as measured by the FRM.

^cMCE – modified combustion efficiency determined using the CO and CO₂ channels of the Picarro Model G2401 CRDS.

^dΔ_C*MCE – interaction between Δ_C and MCE variables.

^eFRM*BC – interaction between PM_2.5 mass concentration and black carbon concentration variables.

Significant variables in bold text.

Data availability statement

Datasets related to this manuscript can be found at https://catalog.data.gov/dataset/epa-sciencehub.