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. Author manuscript; available in PMC: 2024 Nov 15.
Published in final edited form as: Annu Rev Public Health. 2022 Dec 21;44:1–20. doi: 10.1146/annurev-publhealth-071521-120424

Figure 3.

Figure 3

Evidence synthesis results stratified by the type of air pollutant studied. There were a total of 139 studies (76 short-term, 63 long-term), and many studies studied multiple pollutants. The total number of studies (blue-green and pink), number of studies that reported a statistically significant positive association between the air pollutant and COVID-19 outcomes (blue-green), and percent of papers that report significant results (white numbers) are presented for each pollutant. (a) Long-term studies (AQI, n = 3; CO, n = 10; NO2, n = 32; O3, n = 21; PM10, n = 27; PM2.5, n = 52; SO2, n = 14). (b) Short-term studies (AQI, n = 15; CO, n = 23; NO2, n = 35; O3, n = 32; PM10, n = 40; PM2.5, n = 55; SO2, n = 17).