Do air purifiers remove PM2.5?
Thomas here, the nerd behind Smart Air. I’m not an expert in air pollution, but I was living in Beijing during the “airpocalypse” (well, the “first” one) and started to get into building and testing low-cost purifiers.Do purifiers remove PM2.5?I wondered this same question—do air purifiers really get the small particles of PM2.5? I wondered because I saw lots of air purifier tests on pollen, but pollen is generally 10 microns or larger, whereas I was really concerned about the stuff below 2.5 microns.So I went out and bought a laser particle counter. This one tests down to particles 0.5 microns and above.Then I set up a simple DIY purifier in my bedroom in Beijing like this:And here’s what happened to the 0.5 micron particles in my room after I turned it on:I’ve found similar results with three other major purifiers I’ve tested. On average, they removed over 80–90% of 0.5 micron particles from my room air in overnight tests.What about even smaller particles?For the longest time, I thought the effect stopped there. When I read about HEPA filters (the filters in these machines), they always said they capture particles 0.3 microns and above. So I figured they just don’t get smaller particles.Well it turns out I was flat wrong. It’s actually easier for HEPA filters to capture particles smaller than 0.3 microns (thanks to Brownian Motion). As just one example, here’s a test from a dedicated nerd (like me) who has a particle counter that measures down to 0.01 microns. He tested seven major purifiers for 10 minutes.The different purifiers he tested removed about as much of these ultra-fine particles (light blue) as larger particles (dark blue).Bottom line: HEPA purifiers remove PM2.5—even the smallest particles of PM2.5.So breathe easy!P.S. Big purifier companies often use this misconception about HEPA filters to sell you own their own “proprietary” filters, like in the popular Molekule purifier.Now that you’ve seen the data, you won’t fall for this trick!
My Chinese friend said that China will eventually become democratic anyway, but the growing hostility between China and the West would be forever irreversible. Do you agree?
Nothing lasts forever man.China is not competing with the West. It is competing with the United States. There’s no all-out hostility between China and the West, e.g., China-Germany relations are stable and both sides recently compromised on human rights—a long standing issue between the two.Define West. The West is based on shared historical heritage: Greek culture, Roman customs, Reformation, Age of Discovery and overseas colonialism, Renaissance, and Enlightenment. It is not based on a shared political identity such as democracy. Being non-democratic does not lead to alienation or hostility. Case in point—Francoist Spain.Thus, China-US hostility is not about China being non-democratic or communist. Another case in point—Vietnam, whose relations with the US improved since 2009.Diplomatic relations are easily reversible. Case in point—Imperial Japan and Nazi Germany before and after WWII.China’s democratization does not improve its relations with the US. Case in point—Chinese village election reforms started in 1980. Throughout the 1980s China-US relations deteriorated, with China falling from a quasi US ally to a bunch of political deplorables. The decade was ended with the 1989 Tiananmen Incident and comprehensive US arms embargo against China.Which brings us to these conclusions:China-US hostility can be ended. Either through the US giving up imposing not only its cultural values but also political ones on China, or a war that absorbs China into the US or the other way around.There is no but between China’s democratization and China-US hostility. No causality.
Is an artificial hair transplant effective?
Below is an answer from Dr. Parsa Mohebi, a hair transplant expert in Los Angeles. Here is the link: Implantation of Artificial Hair | Parsa MohebiI hope this helps!At the outset, it is important to distinguish between implants and transplants of hair. In contrast to transplants that use patient’s own hairs, usually taken from the occipital area, implants indicate the implantation of prosthetic hair fibers just as artificial hair implantation does.There are two types of prosthetic hair:Synthetic fibers (such as monoacrylic, polyacrylic, and polyester)Natural fibers (such as processed human hair).They are implanted into the galea (which is the fibrotic layer underneath the skin and fat layer under that) by use of a knot through an implanter device. The advantages claimed with this technique are the relative ease of the procedure, which can be learned in a few days, relatively bloodless technique, and immediate cosmetic result. In contrast to transplants however, these fibers do not grow and hence cannot be cut or shaven. In this respect, they resemble a wig, which has been fixed permanently to the scalp.Problems with synthetic hairsThese fibers have had a checkered history. First introduced in 1970s, they soon became the subject of much controversy because of their numerous complications including recurrent infections, rejection, periodic loss of fibers needing frequent replacement, frequent allergic reactions leading to severe contact dermatitis, irritant effects, fears about carcinogenicity, cicatricial alopecia, granulomatous hypersensitivity, and cyst formation.In 1983, the US Federal Drug Administration banned the fibers for the following reasons:The fibers presented risks of illness or injury owed to the non-biocompatibility of the fibers and non-medical performance of the implant.The fibers presented fraud owing to the following:Deceptive information on the efficacy.Inadequate information on risks from implant.They did not show any benefit for public health.The ban on prosthetic hair fibers is established in Section 895.101 of Code 21 of Federal regulations of the FDA, title 21, vol. 8, revised as of April 1, 2004.