Why air pollution levels may be higher inside your home than outside | Billings News

By Stephen Beech

Air pollution levels may be higher inside your home than outside, warns a new study.

People may be exposed to unhealthy levels of airborne pollutants in their own living space – even if the outdoor air quality is good, say scientists.

Researchers at the University of Birmingham used low-cost sensors and innovative techniques over a two-week period to compare particulate matter (PM) in three homes.

Their findings, published in the journal Scientific Reports, show that pollution levels in each house were higher and more variable than outdoor levels.

The researchers found “significant” differences in PM levels between the three houses, with one home exceeding the World Health Organization (WHO) 24-hour PM2.5 limit on nine days.

The team says the study highlights the importance of monitoring indoor air quality at a household-specific level.

Study co-author Catrin Rathbone said: “Our study shows the need to monitor indoor air pollution, as people can have unhealthy air at home even if outdoor air is good.

“PM levels varied significantly between homes, indicating that monitoring just one location isn’t enough.”

The team noted that factors such as household location, ventilation, and occupancy patterns influenced particle levels – showing the complexity of indoor air quality.

Study co-author Owain Rose said: “With more time spent working from home, understanding the factors that affect air quality within households is increasingly important.

“The methods we used accurately modeled indoor PM levels, helping to improve exposure estimates at a low cost.”

The research team identified five different factors contributing to PM in indoor spaces – two relating to indoor activities, such as increased movement by residents, and three linked to external factors such as a nearby restaurant’s kitchen vent.

They found that larger particles (PM10) tended to settle faster compared to smaller particles (PM1, PM2.5).

The three households studied were within the Selly Oak area of Birmingham. Each house was occupied by four or five people, and all were fitted with gas central heating and a gas-fired combined hob and oven.

Researchers used Non-negative Matrix Factorisation (NMF) – a tool for uncovering latent patterns in data – to more accurately model indoor PM levels.

Using low-cost sensors enabled them to build a more detailed picture of pollutant levels within the properties.

Study co-author Professor Francis Pope added: “Our approach is easily scaled due to its low cost and would allow air quality management in homes across Britain and beyond.

“This could lead to more accurate pollution exposure models and better-informed public health policies.”