Other sites where friends describe their projects:
Romek Kubat's blog (in Polish)
Cezarowy Blog (in Polish)
IoT projects:
ESPEasy 2.0 – installable versions (binary)
– Gijs Noorlander Projects
SMOG, air quality and purification:
SMOG measurement project on ESP8266 – all in one, various devices – Air Quality from Jan Szumiec
Do-it-yourself – air purifier
Advanced design with ESP8266, smog sensor and heating (enc-X)
Jack's project - better charts for SMOG, here is the blog https://consolechars.wordpress.com/
SMOG/meteo stations:
Łukasz Trąbiński and his station METEO.