Â鶹´«Ã½

Last Word is Â鶹´«Ã½â€™s long-running series in which readers give scientific answers to each other’s questions, ranging from the minutiae of everyday life to absurd astronomical hypotheticals. To answer a question or ask a new one, email lastword@newscientist.com

Is it better to walk a mile along a busy main road for exercise, or catch a bus to cut down on the time when you are subject to high pollution?

Dudley Miles
London, UK

From an evolutionary perspective, why do we “ghost” people (suddenly cut off all contact) and what effect does it have on them?

Caroline Deforche
Lichtervelde, Belgium

To answer this question – or ask a new one – email lastword@newscientist.com.

Questions should be scientific enquiries about everyday phenomena, and both questions and answers should be concise. We reserve the right to edit items for clarity and style. Please include a postal address, daytime telephone number and email address.

Â鶹´«Ã½ retains total editorial control over the published content and reserves all rights to reuse question and answer material that has been submitted by readers in any medium or in any format.

Terms and conditions apply.