I just finished a week of trying to find the right air purifying solution for my home, and since it is high time for a new blog post, here is my little guide to breathable air in Beijing:
November 2011 was the first time I came to Beijing. In retrospective, that visit was a very lucky one – air wise:
In January and February 2014, I experienced my first >500 PM 2.5 dose, that was not cool. This year, I have been staying in Beijing since January, so basically the whole year, and the air has been surprisingly clean (meaning I cannot recall the PM 2.5 value going above 300 more than 2 times)….But this week, the small particles struck back.. five days in a row.
During those 5 days I went on a quest to keep the PM 2.5 value under 50. It turned out to be quite difficult, even with already two Xiaomi air purifiers (2nd gen) in my home.
Here is the little journey:
1. Turn off the heating
My apartment is heated via a central ventilation system. And the air which comes out of the vents seems to be coming directly from outside without any filtration. The laser egg showed values >300 when held close to the vents.
With the heating off, a large source of dirty air was eliminated, but then there was the temperature problem. This was solved with this:
2. Order more air purifiers
I already had 2, but since the flat has a bedroom, a living room with a kitchen area and a bathroom, 2 seem not to be enough. Even with both purifiers running on full speed (which is quite loud to be honest), I couldn’t keep it below 100.
So I needed a new one. But which one? Browsing Jingdong gave me the feeling that there are 128974872 air purifiers asking for some of my money. I decided to try out 2 very different ones:
I got an offer on the Philips: 3299 RMB. STILL 7 times more expensive than the DIY solution (which included a HEPA and a activated carbon filter!)
3. Seal leaking doors and windows
I checked the windows and the apartment door for leaks, and found out that my door lets in lots of pollution. It simply wasn’t sealed properly. So I did this:
Of course it didn’t help much. Therefore I bought some rubber tape to seal the leak. And right after the tape was on, there was a big improvement already:
Now, with 4 air purifiers, a properly sealed door and unpolluted heating, I manage to have this in my apartment, while outside we have 250:
One comment on the air purifiers:
I think that the Xiaomis do a very good job, but using the EUPA fan combined with the filters seems to be much more efficient. This is in line with what I have read in several places, mostly here: My Health Beijing, all you need to clean your air is the right filters and a big fan.
To be honest, I think 3 air purifiers are enough for my apartment, especially now that the door is properly sealed. But I like to believe that having 4 puts less stress on each of them, so I can use them (and especially the filters) longer.