Table 4.

Nitrogen oxides (NOx), nitrogen dioxide (NO2), long-term and short-term health outcomes.

Environmental Risk Factor	Exposure Unit or Comparator	Exposure Temporality	Study Design	Population	Health Outcome	Studies Included	Reference	Year	I2 (%)	p-Value	Risk Estimate	Effect Size	LCI	UCI	Strength of Evidence
NO2	per 4 mcg/m3	Long-term	Cohort	Adults, both sexes	Autistic syndrome disorder	7	[17]	2020	58	0.007	RR	1.02	1.01	1.04	Low
	per 10 mcg/m3				Cancer mortality	16	[7]	2018	95	0.003	RR	1.06	1.02	1.10	Low
					Cardiovascular mortality	18	[11]	2014	98	NR	RR	1.13	1.08	1.18	Low
					Chronic kidney disease	3	[5]	2020	0	0.47	RR	1.11	1.09	1.14	Moderate
					All-cause mortality	12	[11]	2014	89	NR	RR	1.04	1.01	1.06	Low
					Respiratory mortality	9	[11]	2014	0	NR	RR	1.02	1.02	1.03	Moderate
					Type 2 diabetes	6	[26]	2018	46	<0.001	RR	1.11	1.07	1.16	High
					Cancer mortality	16	[7]	2018	95	0.003	RR	1.06	1.02	1.10	Moderate
				Children	Asthma	20	[36]	2017	65	<0.001	OR	1.05	1.02	1.07	Moderate
				Pregnant women	Low birth weight	11	[18]	2019	32	NR	OR	1.02	1.00	1.04	Moderate
					Small for gestational age	5	[18]	2019	87	NR	OR	1.02	1.01	1.03	Low
	per 10 mcg/m3	Short-term	Time-series	Adults	Natural mortality	30	[16]	2015	NR	NR	RR	1.002	1.002	1.004	Low
	per 10 ppb		Case-crossover	Adults, both sexes	Out-of-hospital cardiac arrest	11	[21]	2017	66	NR	RR	1.02	1.00	1.03	Low
			Time-series	Adults, both sexes	Cardiac arrhythmia	13	[22]	2016	93	NR	RR	1.04	1.01	1.05	Low
					Conjunctivitis	12	[27]	2019	NR	NR	RR	1.02	1.01	1.04	Low
	per 20 ppb				Depression	7	[28]	2020	65	0.008	RE	1.02	1.00	1.04	Low
				Children (<18 years)	Pneumonia	10	[24]	2017	71	0	RR	1.01	1.00	1.02	Moderate
NOx	per 20 ppb	Long-term	Cohort	Pregnant women	Low birth weight	3	[18]	2019	58	NR	OR	1.03	1.01	1.05	Low
					Preterm birth	5	[18]	2019	88	NR	OR	1.02	1.01	1.03	Low

LCI: lower confidence intervals; UCI: upper confidence intervals NR: No reported; RR: relative risk; OR: odds ratio.