Table 1.

Evidence of association between ambient air pollution and neurological disease.

Diseases	Subjects	Study design	Exposure level (component)	Result	References
Dementia	9,817,806	Meta-analysis	PM2.5	Long-term exposure PM2.5 accreted time to first hospitalization for dementia.	(11)
	130,978	Retrospective cohort study	PM2.5 and PM2.5 from traffic	Positive association between residential levels of air pollution across London and being diagnosed with dementia.	(12)
	95,690	Prospective cohort study	PM2.5, O3	Long term exposure to PM2.5 and O3 above the current US EPA standards are associated with increased risk of AD.	(8)
	2,066,639	Prospective cohort study	PM2.5, NO2	15, 813 cases of dementia (or 6.1% of total cases) were attributable to elevated air pollution.	(16)
	19,409	Prospective cohort study	PM2.5, PM10	Rate of cognitive decline was significantly higher in women with highest level of exposure to PM2.5 compared to lowest level.	(10)
	20,150	Prospective cohort study	PM2.5	Exposure to PM2.5 was not associated with incident cognitive impairment, even when analysis was run on participants with more than 12 months of exposure data.	(74)
	2,867	Prospective cohort study	PM2.5, PM10 (w/or w/o Traffic)	Exposure to PM2.5 and PM10 was associated with memory decline in participants.	(75)
	130,978	Retrospective cohort study	PM2.5, NO2, O3	Increased risk of dementia with increased exposure to PM2.5 and NO2. Decreased risk with greater exposure to O3.	(12)
	2,066,639	Prospective cohort study	PM2.5, NO2, O3	PM2.5 and NO2 is associated increased risk of dementia. But, increased exposure to O3 was not associated with incident dementia.	(16)
	5,116	Case-Control design	PM2.5, O3	Presence of at least one APOE4 allele was associated with faster decline for air pollution. O3 exposure effects were not significant in cognitively impaired but associated with faster decline for all exposure.	(76)
	243,611	Prospective cohort study	PM2.5, NO2	Living closer to a roadway was associated with increased risk of dementia.	(16)
	29,547	Case-Control design	NO2, CO	Highest levels of NO2 and CO exposure was significantly associated with increased risk of dementia.	(77)
Stroke	65,893 (Postmenopausal women)	Prospective cohort study	PM2.5	Stroke incidence increased by 35% and stroke deaths increased by 83% after exposure to PM2.5.	(22, 78)
	124,614	Prospective cohort	PM2.5	Stroke incidence increased by 19% after exposure to PM2.5.	(26)
	836,557	Prospective cohort study (Patient)	SO2	Stroke incidence increased by 4% after exposure to SO2.	(29)
	24,066	Prospective cohort study	PM2.5	Stroke hospitalization increased by 3.49% after the exposure to PM2.5.	(27)
	9,941	Retrospective cohort	PM10, NO2	Stroke mortality increased by 49% for PM10 and 144% for NO2.	(79)
	99,446	Meta-analysis	PM2.5	Overall stroke incidence increased by 19%. Increased risk was observed even at concentrations that met the European Union standard of 25μg/m3.	(80)
	379	Retrospective cross-sectional study	PM10, PM2.5, NO2, O3, SO2	Air pollution levels correlate with ischemic stroke admission.	(81)
	2,640,000	Case-Control design	PM2.5	Air temperature influences air pollution and hospital admission for stroke.	(82)
	10,663	Case-Control design	NO2	NO2 levels during the cold season is associated with increase stroke admissions.	(83)
	3,362	Prospective cohort study (Time-series design)	NO, SO2, CO, organic carbon	Each component associated with hemorrhagic stroke.	(84)
	26,210	Case-Control design	O3	O3 exposure associated with increased stroke hospitalization risk.	(85)
Depression	118,602 DD (Depressive Disorder)	Case-Control design	PM2.5, NO2, SO2, O3	The ozone was more strongly associated with depressive symptoms in warm season. But there was no association with PM2.5, SO2, or NO2.	(35)
	19,646 DD	Case-Control design	PM2.5, PM10	The PM2.5 and PM10 were associated with incidence of depression, and aging is a susceptibility factor.	(86)
	27,047 DD	Time-series study	PM2.5, NO2, SO2, O3	The PM2.5, NO2, SO2, and CO had significant association with depression in warm season.	(38)
	4,985 DD	Case-Control design	PM10, NO2, SO2, O3	The PM10, NO2, SO2, and CO had significant association with depression.	(36)
	680 DD	Case-Control design	O3	The O3 was strongly associated with depression in women.	(37)
	973 DD	Prospective cohort study	PM2.5	The PM2.5 is associated with incidence of depression and chronic disease is a susceptibility factor.	(87)
Schizophrenia	943, 027	Meta-analysis	Urban vs. suburban	Natural environments during childhood may be important for schizophrenia prevention.	(57)
	10,947 MDs (Mental Disorder)	Case-Control design (Time-series)	PM2.5, PM10, PMc	PM exposure might be an important trigger of hospitalizations for MDs.	(61)
	1,193 SP (Schizophrenia patients)	Cross-sectional Study	PM2.5	Ambient PM2.5 concentration was associated with exacerbation of schizophrenia.	(64)
	34,865 SP	Case-Control design (Time-series)	PM2.5, SO2, NO2	Ambient air pollution (PM10, SO2, NO2) can be associated with increased risk of daily outpatient visits for schizophrenia.	(59)
	11,373 MDs	Case-Control design (Time-series)	NO2	Short-term exposure to NO2 may be associated with increased schizophrenia hospital admissions.	(62)
	2,232 (Children)	Cross-sectional study	NOx, PM2.5, PM10	Air pollution exposure-particularly NO2 and NOx-was associated with increased odds of adolescent psychotic experiences, which partly explained the association between urban residency and adolescent psychotic experiences.	(60)
	3,469 MDs	Case-Control design (Time-series)	PM10, SO2, NO2	It significantly increased the risk of schizophrenia episode in subjects who were male, aged 20–59, farmers, and workers.	(63)

MD, Mental Disorder Patient; DD, Depressive Disorder Patient; SP, Schizophrenia Patient.