FIGURE 2
PM 2.5 and Ozone (O 3 ) Levels and Relationship With COVID-19 Cases for March 1–June 30, 2020, in the United States
A
C
B
D
Note. A) PM 2.5 data, B) O 3 data, C) confirmed cases logarithmic numbers with monitored data of PM 2.5 , and D) confirmed cases logarithmic numbers with monitored data of O 3 (Xu et al., 2022). Figures reproduced with permission from Elsevier (No. 5874480227563).
Reports found that wearing masks and keep- ing the proper social distance could prevent viral transmission if many people complied with masking instructions (Hadi, Kadhom, Yousif, et al., 2020). Thus, it became impor- tant to study and design face masks to make them more effective for preventing COVID- 19 infection. Studying commercially available masks and finding the best among them was there- fore a priority. Sousan et al. (2021) stud- ied three types of face masks that health- care providers were using: Halyard H600, NIOSH-certified N95, and P100. The filter part of the face masks was exposed to air- borne salt particles with a flow rate of 43
LPM and relative humidity of 40% ± 2%. Particle penetration was examined by an aerosol spectrometer and the efficiency of the face masks was tested by measuring the concentration of airborne particles before and after filtration. Testing showed the P100 performed best, removing 100% of particles ≥250 nm. The N95 was second, with a fil- tration efficiency of 97% ± 1%, 99% ± 0%, and 100% in removing 275 nm, 324 nm, and >450 nm particles, respectively. Lastly, the Halyard H600 efficiency was moderate compared with the others. It removed 275 nm, 324 nm, and >450 nm particles by 62% ± 28%, 89% ± 8%, and 100%, respectively. Additionally, the Halyard H600 showed the
highest pressure drop compared with others after a short testing time. Part of the effort to develop better face masks focused on improving open mem- branes to limit or prevent COVID-19 trans- mission. Moon et al. (2021) synthesized a double-comb copolymer nanofibrous mem- brane by using electrospinning and atomic transfer radical polymerization methods to filter PM 0.3 . The membrane had an am- phiphilic property because it was prepared from poly(vinylidene fluoride) (PVDF) grafted with poly(oxyethylene methacrylate) (POEM). The membrane was characterized by different techniques and showed a removal efficiency of 93.56% with minor resistance to
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March 2025 • Journal of Environmental Health
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