The air in São Paulo today has a hazy, slightly heavy feel to it, like the city is wrapped in a thin, grey blanket that holds onto the smells of traffic and industry. Breathing might not feel sharp or painful, but there's a definite thickness to it, a kind of stuffiness that makes you notice each breath just a little more.

It's one of those days where a long, vigorous run in the park might leave you coughing more than feeling refreshed, so it's smart to take it easier if you're planning outdoor exercise. You can still go outside for a short walk or to run a quick errand, but you might want to keep the windows shut for now to keep that heavy feeling from settling inside your home.

If you have young children, are an older adult, or live with any kind of lung or heart condition, this is a day to be especially gentle with yourself and avoid spending long periods outdoors. Your body is working a little harder than usual just to process the air, so giving it a break by staying in a cleaner indoor space is a kind, practical choice.

The good news is that this hazy spell is usually temporary, often shifting with the afternoon breeze or a change in the weather. For now, treat it like a lazy Sunday indoors: keep the windows closed, relax a bit more than usual, and know that fresher air is likely on its way.