Shanghai Blog

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Lite bilder från 10:e juni på Shanghai Zoo.

Posted: 08 Aug 2016

I bought a board with a laser sensor counting small particles in the air that I use at home. I bought it online, you can see the website (taobao store) printed on the circuitboard. What is nice about this product is that is as more detailed information about the readings than other products that only output an air quality index. I has a button on the side to flip between the 2 screens. The first screen shows air quality in terms of PM1.0, PM2.5 and PM10 (PM2.5 are particles with a diameter of 2.5μm or less). The second screen shows the counters of how many particles the laser sensor actually counted in the different ranges.

The laser sensor is installed below the TFT-screen and circuitboard. The laser sensor is a PMS5003 made by Plantower (a Chinese brand). It’s powered by a micro-USB cable.

From the PMS5003 technical specifications:
Minimum diameter: 0.3um
Counting efficiency: >50%@0.3μm; >98%@0.5μm

So it’s not very accurate for particles of 0.3μm or less, but has a good accuracy above 0.5μm. I guess the fan performance will be the most critical part longterm for this sensor. If the airflow would be reduced the air quality calculations will be incorrect. I paid 320 RMB for the sensor with screen/circuitboard setup. The sensor itself is around 110 RMB according to I bought it in December 2015, so I have already been using it for over 6 months, and so far it seems to work good.

I have noticed that if I don’t run the HEPA-filter air unit at home (I use it in the bedroom) and I keep windows closed, the air quality indoors is about half as dirty as the outdoor air. For example if the online Shanghai PM2.5 data shows an index of 150, I can guess quite accurately that the indoor value in my apartment will be about 75. If I cook food and have some smoke the quality will rapidly rise very high (easily 400 or more).

• is a website with realtime air quality readings all over China
• PM stands for particulate matter, usually given in μg/m3 (or g/cm3)

Posted: 02 Aug 2016

An interview interchange between Jerry Seinfeld and Judd Apatow from Apatow’s book, “Sick In The Head”:

Jerry: I used to keep pictures of the Hubble [Telescope] on the wall of the writing room at Seinfeld. It would calm me down when I would start to think that what I was doing was important.

Judd: See, I go the other way with that. That makes me depressed.

Jerry: Most people would say that. People always say it makes them feel insignificant, but I don’t find being insignificant depressing. I find it uplifting

Quote from

Posted: 02 Aug 2016