The levels of airborne micropastic in Auckland’s air were many times higher than those recorded in London, Hamburg and Paris in recent years, the scientists say, noting that they used sophisticated chemical methods to locate and analyse particles as small as 0.01 of a millimetre.

The average number of airborne microplastics detected in a square metre in a day was nearly 5,000, as compared with fewer than 800 in London, 275 in Hamburg and slithtly over 100 in Paris, although these latter figures were recorded several years ago via less sophisticated means.

“Future work needs to quantify exactly how much plastic we are breathing in,” stresses Dr Joel Rindelaub, an expert at the School of Chemical Sciences at the University of Auckland who was the author of a new study. “It’s becoming more and more clear that this is an important route of exposure.”

Importantly, it was found that particle sizes changed with the direction of winds. When winds passed over the centre of Auckland, the microplastics downwind were larger, indicating the plastics had gone through less environmental aging and came from a closer source, the scientists say.

“Polyethylene (PE) was the major substance detected, followed by polycarbonate (PC) and polyethylene terephthalate (PET). Polyethylene and PET are packaging materials while PC is used in electrical and electronic applications. All three are also used in the construction industry,” they report.

The scientists examined the microplastics content of air by capturing particles in a funnel and jar placed on a rooftop at the university’s campus and in a residential garden. They then identified the smallest particles by applying a coloured dye that emits light under certain conditions.

“The smaller the size ranges we looked at, the more microplastics we saw,” Rindelaub says. “This is notable because the smallest sizes are the most toxicologically relevant.”

The smallest particles called nanoplastics can potentially enter our cells and cross the blood-brain barrier. They could also build up in our organs such as lungs and liver, causing long-term damage, the scientists note.

In other research recently scientists found that microplastics can enter our circulatory system, raising the specter of serious health issues over time.