Concerned about the PM2.5 air quality, and the lack of online data for my location (the websites simply interpolate data from 2 distant monitors in other cities), I bought a monitor off Aliexpress.
Well, the unit switches on, displays a PM2.5 value, and that value increases as the smoke density rises. But the values seem completely at odds with the online interpolated data.
In my garden, the normal reading is about 20, which I refuse to believe as correct, (Phuket has very clean air and typically has a value of about 50 - I live in the hills with local scrub burning at times). Online data suggests about 70. If I walk past a dusty building site, the value rises to about 55.
The monitor is made by a Chinese company called 'Total B0ll0x Factory #5'.
Can anyone recommend an accurate air quality monitor that I can buy from Aliexpress (not Lazada - I live in Laos)?