I don’t know where you’re getting these numbers from. What kind of generator are you talking about? Emissions change with power and fuel use.
The average US home uses 30kWh of electricity per day, with a 0.4l/kWh fuel consumption that would give us 12l of diesel consumption per day. Diesel has about 2.65kg/l of CO2 emissions, which for 12l would give us 31.8kg or 31,800g of CO2 per day.
The average US apartment is 82.4m2 big, with 2.5m of wall height this would give us a volume of 206m3 of air volume (disregarding furniture etc., realistically less). Air has a density of 1.3kg/m3, meaning we would have 267.8kg or 267,800g of air in this space.
The instantly harmful CO2 concentration is around 10%. This means in 267,800g+10% = 270,478g of air 10%, or 2,705g, of CO2 would need to be introduced. With 31,800g of CO2 generation per day, we would have an instantly harmful concentration of CO2 in about 2,705/31,800 = 0.08, 0.08*24h = 2.04h. You would be dead pretty quickly.
Not to mention CO, which would kill you even quicker.