The researchers theorized that urban areas with busy roadways might have regional deicing salt plumes or mists for several days after a snow event. This increases total salt accumulation on buildings. In Chicago, deicing salt-related metal corrosion has been found up to the 60th floor of one tall building.2 Exposure levels are likely to be similar in any major city with regular winter snow exposure.
Internationally, it is estimated that over 60 million metric tons (66 million tons) of salt are used for deicing.3 China, which previously used very little deicing salt, has had a considerable increase in usage and recently became the world’s largest producer.
In the US, about 70% of the roads and population areas receive at least 13 cm (5 inches) of snow annually and additional areas are affected by seasonal freezing rain. In recent years, the United States used 13.6 to 18 million metric tons (15 to 20 million tons) of deicing salt per year and Canada used another 3.6 to 4.5 million metric tons (4 to 5 million tons).4
Many Europeans incorrectly assume that their deicing salt use is quite minimal, but it is actually similar to North American use. Deicing salt tonnage is increasing in both regions. For example, the salt industry association, Verband der Kali- und Salzindustrie e.V., reported that over 3 million metric tons of deicing salt were used on German roads during both 2005 and 2006, which is a 50% increase since 2002.5
The most comprehensive European study was done in 2002 when twenty countries participated in a task group that studied deicing practices. Table 1 summarizes the deicing methods used in each country, and, where available, the annual tonnage. It is evident from this and other data sources that deicing is standard practice throughout Europe.