air can be changed if their is enough gas to change it also the air a long time ago was mainly hydrogen and helium now it is mainly oxygen, carbon dioxid nitrogen
Some air purifiers do require a filter to be changed others have a filter that can be cleaned.
because it does
The filters in an air purifier ususally need to be changed around every 3 - 6 months but it also depends greatly on what kind of air purifier you have .
1953 by jawaharlal nehru
True
When it is dirty.
When it is dirty.
Air filter should be changed at least once a year or whenever the indicator goes off on the dashboard, whichever comes first.
Yes, Yes they do
True
They are using new tecnology to improve
Heater core changed three years ago,I changed Thermostat Heater still blows cool air.