While discussing today about the faq entry on PM10 versus PM2.5 which I posted yesterday, my friend Klaus challenged on the usefulness of protection masks. He was actually wondering if the modern masks can nowadays really filter efficiently all the small harmful PM2.5 particulate matter?
Actually, this is a very good question! If you have to wear a mask in Beijing, then better to make sure that it really filters the bad particulates.
Since I did not have the answer to his question, I just dropped an email to Francis Chu from the Singapore totobobo® mask manufacturing company, who replied in almost no time:
Yes, our Totobobo mask is able to cut down 99.85% of 0.1 microns particles.
You can download the lab report: totobobo.com/download/F96-NelsonLab-test.pdf
For the readers not familiar with particles size, PM10 refers to particles smaller than 10 micrometer, and for PM2.5, it refers to smaller than 2.5 micrometers. So, filtering out all the particulates smaller than "0.1 microns (same as 0.1 micrometers)", means that it can filter particles 25 times smaller than the harmful PM2.5! So, no worries Klaus, the newest technologies are definitely efficient!
For more information about particles size, you can refer to the wikipedia page. If you want to learn more about how air filters are actually tested, or how the various mask brands compare to each other, check this very informative totobobo blog entry.
And if you just want to get your own totobobo mask, click here.