Indoor air quality and how it shapes the way you feel

Most people spend close to 90% of their time indoors, which means the air inside a home has far more influence on daily health than the air outside. Still, indoor air is almost never measured in the places where we sleep, cook, work and raise children.

What indoor air is actually made of

Indoor air is a mixture of what enters from outside, what is generated inside, and what stays because ventilation is insufficient. Cooking, cleaning products, furniture, paints, moisture and combustion appliances all add particles and chemical compounds to the mix.

Two of the most useful indicators are fine particles (PM2.5) and carbon dioxide. Fine particles are linked with respiratory and cardiovascular effects, while carbon dioxide is a practical proxy for how well a space is ventilated and is associated with drowsiness and reduced concentration.

Simple places to begin

Ventilate intentionally rather than occasionally: use the kitchen extractor every time you cook, run bathroom fans during and after showers, and open windows when outdoor conditions allow. Filtration helps where ventilation cannot, particularly in bedrooms.

Reduce sources where you can. Fragranced products, aerosols and unvented combustion are common contributors that are easy to change without renovation work.

Why measurement matters

Perception is a poor instrument. A room can feel fine and still show elevated particles or carbon dioxide. Measuring turns assumptions into evidence, and evidence into a short list of changes worth making first.