Table 3.

Association between postnatal exposure to air pollution and childhood obesity in human epidemiologic studies

Study		Country	Study design	Study population			Obesity parameter	Air pollutant	Direction of relationship with obesity (+/-/0)	Findings
				Sample size (n)	Age at exposure (yr)	Age at outcome (yr)
Traffic density/proximity
	Jerrett et al. [25] 2010	USA	Cohort	2,889	9–10	18	BMI	Traffic density	(+)	Positive association with attained BMI over 8 study years
	Jerrett et al. [26] 2014	USA	Cohort	4,550	5–7	10	BMI	Traffic density	(+)	Positive association with attained BMI at the age of 10
	Amram et al. [27] 2019	USA	Cross-sectional	10,327	10–11	10–11	BMI	Arterial road exposure	0	No association with overweight
NOx/elemental carbon
	McConnell et al. [28] 2015	USA	Cohort	3,318	10	18	BMI	NOx	(+)	Synergism between tobacco smoke and NOx exposure on attained BMI at the age of 18
	Alderete et al. [29] 2017	USA	Cohort	314	8–15	18	BMI	NO2	(+)	Positive association with BMI and SAAT at the age of 18
							Body fat%
							SAAT
							IAAT
	Kim et al. [16] 2018	USA	Cohort	2,318	1	10	BMI	NOx	(+)	Positive association with attained BMI at the age of 10
	Fioravanti et al. [32] 2018	Italy	Cohort	719	0, 4	4, 8	BMI, WC, WHR	NO2	0	No association with childhood obesity
	Bloemsma et al. [30] 2019	Nether-lands	Cohort	3,680	12–14	3–17	BMI	NO2	(+)	Positive association with overweight
	de Bont et al. [31] 2019	Spain	Cross-sectional	2,660	7–10	7–10	BMI	NO2	(+)	Positive association with overweight/obese
PM
	Kim et al. [33] 2016	Korea	Cohort	1,129	0.5–1	1–5	Weight-for-age	PM10	(-)	Negative association with weight at the age of 12–60 mos
	Mao et al. [18] 2017	USA	Cohort	1,446	0–2	2–9	BMI	PM2.5	(+)	Positive association with childhood overweight or obesity
	Alderete et al. [29] 2017	USA	Cohort	314	8–15	18	BMI	PM2.5	(+)	Positive association with BMI and SAAT at the age of 18
							Body fat%
							SAAT
	Kim et al. [16] 2018	USA	Cohort	2,318	1	10	IAAT	PM2.5	0	No association with attained BMI at the age of 10
	Fioravanti et al. [32] 2018	Italy	Cohort	719	0, 4	4, 8	BMI, WC, WHR	PM2.5 PM10	0	No association with childhood obesity
	Bloemsma et al. [30] 2019	Nether-lands	Cohort	3,680	12–14	3–17	BMI	PM2.5 PM10	0	No association with overweight
	de Bont et al. [31] 2019	Spain	Cross-sectional	2,660	7–10	7–10	BMI	PM2.5	(+)	Positive association with overweight/obese
Smoking
	McConnell et al. [28] 2015	USA	Cohort	3,318	10	18	BMI	Smoking	(+)	Synergism between tobacco smoke and NOx exposure on attained BMI at the age of 18
PAH
	Scinicariello et al. [35] 2014	USA	Cross-sectional	3,189	6–19	6–19	BMI, WC	PAHs	(+)	Positive association with obesity parameters in children

The direction of relationship with obesity: (+), factor related with greater childhood obesity; (-), factor related with decreased childhood obesity; (0), no relationship with childhood obesity.

BMI, body mass index; IAAT, cross-sectional area of intra-abdominal adipose tissue; NO₂, nitrogen dioxide; NOx, nitrogen oxides; PAHs, polycyclic aromatic hydrocarbons PM_2.5, particulate matter <2.5 microns in diameter; PM₁₀, particulate matter <10 microns in diameter; SAAT, cross-sectional area of subcutaneous abdominal adipose tissue; WC, waist circumference; WHR, waist-to-hip ratio.