I’m gonna go with barely, if at all. When you wear a surgical mask and you breath in, a lot of air flows in from the edges, without actually passing through the mask, so the mask doesn’t have very good opportunity to filter the air. At least with N95 and N99 mask, you have a seal around your face, and this forces the air through the filter. Your probably better off wearing a wet bandana or towel that’s been tied in such a way as to seal around your face, but that might make it hard to breath.
I’m gonna go with barely, if at all. When you wear a surgical mask and you breath in, a lot of air flows in from the edges, without actually passing through the mask, so the mask doesn’t have very good opportunity to filter the air. At least with N95 and N99 mask, you have a seal around your face, and this forces the air through the filter. Your probably better off wearing a wet bandana or towel that’s been tied in such a way as to seal around your face, but that might make it hard to breath.
I found this, which suggests that they’re generally ineffective. https://www.cdph.ca.gov/Programs/EPO/Pages/Wildfire Pages/N95-Respirators-FAQs.aspx