Two masks can be worse than one: N95 respirator failure caused by an overlying face mask.

We have demonstrated the effect of covering an N95 filtering facepiece respirator (FFR) with an overlying face mask. In total, 100 participants successfully completed quantitative fit testing wearing a 3M 1870+ FFR. Among them, 13 (13%; 95% CI, 7%-22%) failed subsequent fit testing when simultaneously wearing a Halyard 47117 procedural mask over the FFR.

The importance of various stages of succession in preservation of biodiversity among riparian birds in northern Iran.

Every stage of succession may provide certain species with habitat requirements which are impossible in other stages of succession. This study attempts to evaluate the different stages of succession in terms of composition and structure of bird populations in Hyrcanian forests. Bird-habitat relationships were investigated by comparing vegetation characteristics in three successional stages including late, initial stage, and urban areas.