Russian air pollutants data collected by two Russian federal agencies. Primary agency is Federal Service for Hydrometeorology and Environmental Monitoring of Russia (Roshydromet).
Yearly air pollution quality report prepared and published by The Voeikov Main Geophysical Observatory. It's subsidiary research facility of Roshydromet. Organization website - http://www.voeikovmgo.ru/ (Rus)
Last report was published for 2015 year http://www.voeikovmgo.ru/images/stories/publications/2016/ejegodnik_zagr_atm_2015.pdf (Rus)
first report was public and online since 2006 year http://www.voeikovmgo.ru/download/publikacii/2008/Ezegodnik2006.pdf (Rus)
This report is highly incomplete in terms of open data.
Data for report collected from 688 stations from 249 cities (2015 year) but for report it's aggregated to sub-regional level and much lesser information for each city.
Very limited data like "most polluted cities" and "average air pollution for regions" available at Voeinkov facility website http://www.voeikovmgo.ru/index.php/ru/struktura/otdel-monitoringa-i-issledovanij-khimicheskogo-sostava-atmosfery/laboratoriya-analiza-i-otsenki-sostoyaniya-zagryazneniya-atmosfery (Rus) but it's not open data and even not machine-readable data too. And it's incomplete, not all cities covered and no numeric data provided.
Also this data is not published in official Roshydromet repository - http://www.meteorf.ru/opendata/ (Rus) on it's official website
2. Second agency is "Federal Service for Supervision of Consumer Rights Protection and Human Welfare" (Rospotrebnadzor).
This agency also collects data about water and air pollutants but it's network is even more "shadowed" than Roshydromet one. No data available at agency website http://rospotrebnadzor.ru/ (Rus) and it's official open data repository - http://opendata.rospotrebnadzor.ru/
I've visited every website of every facility owned by Rospotrebnadzor but no one provides not reports similar to Roshydromet report, not raw data.
So requirement "Data should be available for all air monitoring stations or air monitoring zones in a country." is not matched for this data in Russia.
Disclaimer: I am founder of NGO "Informational Culture" and OKI Ambassador in Russia (member of OKI Russia core team). I have no any affilation with Roshydromet or Rospotrebnadzor.