Is the air in your house a homogenous or a heterogeneous mixture? 
What evidence have you seen?

I can say that the air in the area where I live and in much industrial
areas is not homogenous (heterogenous).
The evidence is a long story,but I will give some details:
A lot of pollution which produces a lot of SO2,CO2,CO also a lot of
other substances that help on increasing the level of air
heterogenousity.
Traffic pollution is also a huge fact to talk about....

A homogeneous mixture is one consisting of a single phase of uniform
composition.  (In this context, "phase" means a state of matter, e.g.,
gas, liquid, or solid.  Solids or liquids of different compositions
would constitute different phases).  Heterogeneous mixtures are
mixtures that contain more than one phase or substance.

Because the question asks about the air in someone's house, then
asllan's comment really doesn't pertain.  On the scale of a house, the
composition of the air can usually be taken to be the same throughout.
 There are, however, instances in which the air in a house would be a
heterogeneous mixture.  Can you think of an example?  [Hint: outside
atmosphere on a cloudless day is generally considered to be a
homogeneous mixture, but the atmosphere on cloudy or foggy day would
be a heterogeneous mixture because the atmosphere then consists of a
suspension (a special type of mixture) of small liquid water droplets
(phase 1) in a gas (phase 2).  Do you ever see "clouds" in your house?
 Do you like hot showers?]

My comment was for my area where I live.I really know the definitions
about  the mixtures.
AIR is a mixture of O2+N2+CO2+H2O+....aerosoles etc.
The facts that are described by hfshaw are true.
In some moments AIR is homogenous mixture,but in other statements AIR
is heterogenous mixture.
These two teories can help for solving this problem.
This could be all.