Harmful particles and gases from tobacco smoke can pass through cracks and crevices particularly in older buildings – leading to potential health challenges for apartment residents.

Alireza Afshari, professor and research group leader at AAU’s Department of the Built Environment, discovered that the building material, cTrap, primarily developed to prevent mould, can also be used to reduce the harmful particles and gases from tobacco smoke seeping between apartments.

By separating apartments with a membrane of cTrap, the transfer of ultrafine particles from tobacco smoke can be reduced by up to 60 per cent. Alireza Afshari's research thus has the potential to promote a healthier life, especially for those living in older apartment buildings.

The membrane stops smoke particles

Since 2012, Alireza Afshari has been doing research in areas such as ventilation and airborne particle transfer. Among other things, he’s demonstrated that up to nine per cent of a tenant's tobacco smoke penetrates the apartment above. By using cTrap, that number can be reduced to about three to four per cent.

cTrap was originally developed by researchers from Lund University and is typically used to reduce volatile organic compounds (VOCs) like those caused by mould. Alireza Afshari began studying the material in 2017, and since, his research has expanded the material's potential to include the reduction of tobacco particles spreading between apartments.

The material consists of four layers: An inner and an outer protective layer, an absorbent layer that captivates gases and particles, and a layer that ensures that moisture can still penetrate through the material.

In Alireza Afshari's experiment, cTrap was placed underneath all the floorboards in two test apartments in Copenhagen, and then the corners were sealed with a silicone mixture with a low level of VOCs.

The results proved that cTrap prevented between 30-60 percent of particles passing from the source apartment to the exposure apartment above.

No use of electricity

While Alireza Afshari's previous research shows that air cleaners have a similar reduction capability, he highlights a number of advantages of using a cTrap membrane.

Unlike an air purifier, cTrap does not require the use of electricity, he explains.

Great potential

In the future, the membrane solution will particularly be used for minor renovations of older apartment buildings where a ventilation system does not already exist or is not an option.