We spend an average of 90 per cent of our time indoors, and good indoor air is paramount for our optimum health, wellbeing and productivity. However, indoor air is often contaminated with pollutants from indoor sources, as well as those that have migrated from outdoors, and thus may potentially present a greater risk to our health than outdoor air. This issue of the environmental SCIENTIST examines aspects that are important to understanding how to achieve good indoor air quality. Read about the importance of good indoor air, a monitoring campaign in nurseries and schools, and indoor air quality considerations for companies returning to the office following Covid-19.