One of the challenges of living in a city is that we're rarely able to open the windows. We only open them when it's raining and the outside temperature is moderate because otherwise our home gets a thin layer of black soot.
To help the air seem fresher, I started burning candles, usually fruit or floral-scented. The pleasant smells lighten my mood and make my day just a little better. It's interesting that what I used to consider an indulgence, is now an essential!