You walk outside this morning in São Paulo and the air feels a bit heavy, like the city is wrapped in a thin blanket. Breathing takes just a little more effort than usual, and there's a slight haze that softens the edges of the buildings. It is not a day for a long, hard run or an afternoon of heavy gardening if you can help it. If you were planning to open all the windows for a spring clean, you might want to wait until the air clears up a little. For healthy adults, a short walk to the market or a quick errand is fine, but try to keep it brief and avoid the busiest roads.

If anyone in your family has asthma, a heart condition, or is recovering from a cold, today is a day to take it easier. Older folks and very young children should also take it slower, and perhaps stick to indoor play or quiet activities. The air quality is not terrible, but it is just enough that sensitive lungs might feel a bit scratchy or tight by the end of the day. You might notice that the usual city smells seem stronger or a little stale, especially near traffic.

For most people, this is a day to be sensible rather than to worry. If you need to go out, try to do so in the cooler hours of the morning or after the evening breeze picks up. Keep any windows open just a crack rather than wide open, and if you have an air purifier at home, let it run for a couple of hours. The city feels a little congested today, like a room that needs airing out, but it will pass.

By tomorrow, the breeze should shift and clear things out, so don't let this dull day get you down. For now, take it easy, keep the car windows up on the highway, and maybe enjoy a quiet evening indoors. São Paulo will breathe easier soon enough.