Is your scented candle trying to kill you? Shocking new research finds air pollution is worse inside your home compared with outside due to common household products

Air pollution was worse inside British homes than it was outside for 11 months of the year in 2022, according to a global study by tech company Dyson.

Data from more than 2.5 million Dyson air purifiers around the world was collected in the research for its first Global Connected Air Quality study.

It focused on levels of two types of pollutant: PM2.5s – particles 1/25th the diameter of a typical human hair – and volatile organic compounds (VOCs).

If PM2.5s are inhaled and enter the bloodstream, evidence suggests they can cause serious illnesses including heart disease and dementia.

They primarily come from burning wood and coal in open fires and solid-fuel stoves.

VOCs are gas pollutants that can be emitted by cleaning products or gas cooking, as well as from deodorant sprays, scented candles and even furniture treated with fire-retardant chemicals 

VOCs are gas pollutants that can be emitted by cleaning products or gas cooking, as well as from deodorant sprays, scented candles and even furniture treated with fire-retardant chemicals.

The study showed the worst month for indoor pollution in UK homes was March and the peak time was from 7pm to 10pm.

Hugh Montgomery, Professor of Intensive Care Medicine at University College London, said: ‘We all think of air pollution as being an outdoor or roadside problem. Dyson’s findings give us a valuable insight into the real pollution levels in homes and help us to understand the patterns of pollution.’

In China, Australia, France, Austria, Canada and Spain, indoor PM2.5 exceeded levels outdoors every month in 2022.

But in homes in India, Norway, Poland and Finland the PM2.5 levels were below outdoor levels for six months of the year.

At city level, the annual average indoor PM2.5 level in homes in Milan was more than 2.5 times the outdoor one – a discrepancy higher than any other city studied.

While the effect of air pollution on the lungs is well documented, a recent study from experts at Harvard University showed that there might also be an impact on brain health.

It found that exposure to higher levels of PM2.5 led volunteers to perform poorly in cognitive tests. Other research has shown that children exposed to poor indoor air quality in schools perform worse in maths and reading comprehension tests.