负离子真的管用吗?

 

知乎上有人问负离子空气净化器是不是真的有效。我觉得这个问题很重要,因为经常有人给我转发这类产品介绍,问我这样的机器是不是有效:

 

 

净化神器!Wow! 30秒钟就有洁净空气吗?而且能去除甲醛?CCTV认可?卖过5万多台?太棒了!我要一台。

 

负离子发生器的工作原理是什么?

 

不过话说回来:为什么会有人卖这种产品?是蒙人的吗?

假如这是我的北京卧室,卧室里有负离子发生器,空中有颗粒污染物:

 

 

负离子发生器开机之后,机器会发出负离子:

 

 

因为静电,这些负离子会让颗粒附着到墙上、床上、地上:

 

 

如果有空气测试仪,会显示空中的颗粒比以前少。成功了!

 

等一下#1

 

这些颗粒没有被过滤掉,只是贴到墙上、床上、地上。我想让这些颗粒附着在我的床上吗?

有人测试过北京的空气污染,研究这些颗粒到底是什么。除了灰尘以外,这些颗粒还包括铅、镉和砷–我不想让这些颗粒附到我的枕套上!祝我睡的香!

 

等一下#2

 

就算我不介意让这些颗粒附到我床上,还有另外一个问题。假如我回家:

 

 

我走来走去,坐到床上。这样会让这些颗粒重新飘到空中。以下是我做的非常非常科学的示意图:

 

等一下#3

 

OK, OK, 如果这两个问题还不够,还有另外一个:科学研究发现,市场上的负离子发生器不够强,基本上起不到作用。如果要起到作用,需要用特别强的负离子发生器–需要比市场上的要强。

而且,释放出那么多负离子会产生臭氧,而臭氧对人有害。

 

负离子上法庭

 

因为负离子净化器有这么多问题,美国独立非营利组织发表了报告让消费者避免负离子净化器。一个叫Sharper Image的厂家起诉了;《消费者报告》赢了

 

 

结论:下次如果有朋友给你转发“净化神器”的信息,记得屏蔽这些信息。已经有被验证过的净化器配件:HEPA滤网。HEPA能捕捉这些颗粒,而不让它们贴到床上。

 

 

可以看看我做的HEPA测试:HEPA现场测试

芝加哥大学行为科学系的助理教授; Smart Air创始书呆子。

在 “负离子真的管用吗?” 上有 4 条评论

  1. Thant’s a very good summary on the ionizers subject. Thank Thomas!

    I was also interested in your opinion about this new “Molekule” air purifer:
    http://www.financialexpress.com/india-news/air-purifier-molekule-invented-by-indian-american-better-than-hepa-filter-gets-into-times-top-25-inventions-list/968131/

    Specifically, I wanted your opinion about what the inventor of this purifier had to say about HEPA (and I quote):

    “HEPA (high-efficiency particulate absorber) filters remain the standard technology in existing air purifiers and, unfortunately, many harmful pollutants are too small for HEPA filters to trap. Larger pollutants like bacteria and mold may be collected by such filters, but they remain on the filter surface, multiply and are released back into the air. Because Molekule actually destroys even the smallest pollutants, they are permanently removed from the air you breathe.”

    1. He says that HEPA filters can’t absorb some pollutants that are too small. This is in direct contradiction to what I read about HEPA filters. I’ve read that HEPA filter’s efficiency is rated at 0.3 micron, because 0.3 micron is the most difficult size for HEPAs to filter out. Above or bellow 0.3 microns, HEPA filters are much more efficient (http://www.sentryair.com/blog/hepa-filter/hepa-filters-are-not-sieves/)

    2. He claims that bacteria and mold multiply on HEPA filters, and eventually released back into the air. Do we have proof that this happens? Bacteria and mold fall within PM10, and we know that HEPA filters don’t release PM10 back (at least not more than they absorb), because we see that even a relatively old filter, can still clean a room (so if it does release something, it is way way less than what it absorbs).

  2. I would love an answer or some insight on Noam’s question regarding the Molekule also!! I read the white papers on the product and it does sound awesome. But it’s expensive! Any insight on this product and their claims would be great!

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