For many millennia, salt production had been growing slowly and roughly in line with the increase of world population. With the beginning of the 20th century, industrial uses of salt became important and the volumes of salt that were produced and consumed started to grow at a much faster pace than the world population.
The graph shows historical population growth and the increasing consumption of salt.
Along the line representing the unit consumption of salt (g per person per day), roughly five regimes can be distinguished for the past centuries.
- Before 1900, salt was essentially used for the conservation of food and to spice food. The first artifacts that provide evidence on the use of salt by man go back to 8000 B.C. During this entire period, salt consumption followed roughly population growth and consumption per capita, at least for the last two millennia, can be estimated at around 10 to 20g of salt per person.
- In 1861, industrial production of synthetic soda ash with the Solvay process started, and this is the first large-scale industrial process that used salt as a raw material. As a consequence, per capita consumption increased to over 40g per day by 1930.
- After a period of stagnation during the Second World War, another strong increase in per capita salt consumption is linked to increasing production of synthetic soda ash, but also the beginning of large-scale chlorine production and of course PVC production which started around 1930.
- In the late 1970s, a period of stagnating per capita consumption starts and this is linked to the new alternative mass polymers that partially replace PVC: Polyethylene in the 1950s and Polypropylene in the 1960s.
- The re-increase of unit consumption after 2000 is linked to the growing economies in Asia (and in China in particular), and the re-increase of PVC production. Growing use of de-icing salt as a result of a tremendous increase of road traffic and road networks also contributes to consumption growth in past decades.