The clean breathing craze proves that you can put a price on fresh air

Tech companies are finding innovative and lucrative ways to clean the air in our homes, while sales of purifying plants are blooming

First it was clean eating; now it's clean breathing. Sales of air purifiers are soaring, with the global market expected to be worth 6.2bn by 2024.

The trend is in response to the rise in asthma and allergies linked to poor air quality inside buildings. Research says it can be up to five times more polluted than air outside, with chemicals from cleaning products, aerosols and perfume rivalling diesel fumes as causes of contamination.