The eco guide to the Christmas walk

Going out for a breather after the big meal is a tradition. But now you have to think about the quality of the air you're taking in

The post-lunch Christmas walk is a family tradition in many households. What's not to like? You get to walk off one of the biggest meals of the year. Young or old, most members of the family can manage a gentle stroll and you get some fresh air in your lungs.

But how fresh is that air? A new study by British researchers recently published in the Lancet highlights the fact that older members of the family need to be much more choosy about where they take their exercise.