Studded tires are a popular choice in northern climes come winter, thanks to the extra grip they afford on ice and compacted snow. Some 60 percent of Swedish drivers fit studded tires for the colder months according to Sweden's Transport Administration, Trafikverket. But new research from Chalmers University of Technology in Sweden says they actually cost more lives than they save, and for reasons which may not be immediately apparent.

The key metric the researchers looked at was life-years. The researchers aren't counting the deaths incurred and avoided due to studded tires, but rather the years of life that are lost or saved. And where studded tyres are thought to save between 60 and 770 life-years in Sweden, the cost of their use is 570 to 2,200 life-years.

The major reason for this is the emissions caused by the studs' damage to asphalt roads, from which particles are thrown up. The research was particularly concerned with PM10 particulates, which have a diameter between 2.5 and 10 micrometers. Airborne particulates can cause respiratory diseases, heart attacks and even DNA mutations. They're considered a Group 1 carcinogen by the World Health Organization and the International Agency for Research on Cancer.

The impact of these emissions outweighs the benefits of use alone, the researchers say, accounting for between 66 and 77 percent of the total. The researchers also took into account emissions caused by the production of studded tires versus non-studded tires.

However, another significant factor is the mining of cobalt which is used in the studs. The most abundant source of cobalt is the Democratic Republic of Congo (DMR), where accidents in the small-scale mining industry are not uncommon, but poorly reported. The researchers think that, if anything, the impact of accidents is underrepresented in their research.

But cobalt mining also contributes to conflict in the region, which is another factor the researchers factored in. And the positive impacts of wealth flowing to DMR is hampered by the fact that that wealth isn't well spread – partly as a result of corruption.

Taking everything into account, between 23 and 33 percent of the negative effects of studded tires are felt outside of the countries where their benefit are felt. But few, if any, of the benefits are.

The researchers suggest that driving carefully, choosing good, non-studded winter tires, car and, where possible, taking other means of transport are good alternatives to studded tires.

"How you drive is important, and snow-ploughing and sweeping needs to be done properly," Chalmers University's Anna Furberg says in a press release. "Most cars today also have electronic anti-skid systems fitted, which make them safer to drive at higher speeds. But our study shows that there is more research needed concerning alternatives to studded winter tyres that don't cause these health issues."

The researchers say that future research could be strengthened by factoring in more affects on human health, but that these considerations are only likely to strengthen the already conclusive findings that studded tires do more harm than good.

The team's research, Live and Let Die? Life Cycle Human Health Impacts from the Use of Tire Studs, has been published in the International Journal of Environmental Research and Public Health and can be read in full online.