Table 4.

Grouped weighted quantile sum (WQS) results showing cumulative associations between groups of ${\mathrm{PM}}_{2.5}$ components, based on six identified source factors, and neurocognitive performance in 9- to 10-year-old participants from the ABCD study cohort ($n=\mathrm{8,589}$), 2016–2018.

Outcome	WQS mixture group membership	Estimatea	Standard error	$p$-Value
General cognitive ability	Ca, Si (crustal)	$-2.51\times 10^{-2}$	$1.18\times 10^{-2}$	0.0327*
	${\mathrm{SO}}_4^{2-}$, V (portion of ammonium sulfatesb)	$-1.59\times {10}^{-3}$	$9.44\times {10}^{-3}$	0.8663
	OC, K, Br (biomass burning)	$-4.65\times {10}^{-3}$	$1.02\times {10}^{-2}$	0.6471
	EC, Cu, Fe (traffic)	$2.39\times 10^{-2}$	$7.42\times 10^{-3}$	0.0013**
	${\text{NH}}_4^{+}$, ${\mathrm{NO}}_3^{-}$ (ammonium nitrates)	$-1.19\times {10}^{-2}$	$1.11\times {10}^{-2}$	0.2798
	Pb, Ni, Zn (industrial)	$-1.90\times 10^{-2}$	$8.83\times 10^{-3}$	0.0318*
Learning & memory	Ca, Si (crustal)	$-1.49\times {10}^{-2}$	$1.18\times {10}^{-2}$	0.2075
	${\mathrm{SO}}_4^{2-}$, V (portion of ammonium sulfatesb)	$9.12\times {10}^{-3}$	$8.84\times {10}^{-3}$	0.3026
	OC, K, Br (biomass burning)	$9.49\times {10}^{-3}$	$9.81\times {10}^{-3}$	0.3357
	EC, Cu, Fe (traffic)	$-4.15\times {10}^{-3}$	$9.44\times {10}^{-3}$	0.6599
	${\mathrm{NH}}_4^{+}$, ${\mathrm{NO}}_3^{-}$ (ammonium nitrates)	$-3.35\times 10^{-2}$	$1.10\times 10^{-2}$	0.0025**
	Pb, Ni, Zn (industrial)	$-6.26\times {10}^{-3}$	$9.41\times {10}^{-3}$	0.5062
Executive function	Ca, Si (crustal)	$-1.90\times {10}^{-2}$	$1.31\times {10}^{-2}$	0.1488
	${\mathrm{SO}}_4^{2-}$, V (portion of ammonium sulfatesb)	$-7.85\times {10}^{-4}$	$8.48\times {10}^{-3}$	0.9263
	OC, K, Br (biomass burning)	$2.95\times 10^{-2}$	$1.16\times 10^{-2}$	0.0108*
	EC, Cu, Fe (traffic)	$-2.23\times 10^{-2}$	$1.08\times 10^{-2}$	0.0397*
	${\text{NH}}_4^{+}$, ${\mathrm{NO}}_3^{-}$ (ammonium nitrates)	$-1.70\times {10}^{-2}$	$1.24\times {10}^{-2}$	0.1686
	Pb, Ni, Zn (industrial)	$-4.69\times {10}^{-4}$	$1.04\times {10}^{-2}$	0.9639

Note: Br, bromine; Ca, calcium; Cu, copper; EC, elemental carbon; Fe, iron; K, potassium; ${\text{NH}}_4^{+}$, ammonium; Ni, nickel; ${\mathrm{NO}}_3^{-}$, nitrate; OC, organic carbon; Pb, lead; ${\mathrm{PM}}_{2.5}$, fine particulate matter with aerodynamic diameter $\le 2.5\mathrm{\mu }\mathrm{m}$; PMF, positive matrix factorization; Si, silicon; ${\mathrm{SO}}_4^{2-}$, sulfate; V, vanadium; Zn, zinc.

^a Estimates are per 1-unit increase in the grouped WQS index, interpreted as an $\sim 1$ decile increase in source factor groups. Results from grouped WQS regression models wherein the 15 PM components grouped into six source factors, adjusting for age, sex, race/ethnicity, overall household income, perceived neighborhood safety, urbanicity, physical activity, and daily screen average hours and site.

^b PMF-identified ammonium sulfates components (${\mathrm{SO}}_4^{2-}$, V, and ${\text{NH}}_4^{+}$) were reduced to ${\mathrm{SO}}_4^{2-}$, V (likely reflecting coal-burning power plants) to reduce overlap of ${\text{NH}}_4^{+}$ in grouped QWS analysis. Significance levels: *indicates $p$ < 0.05; **indicates $p$ < 0.01.