The world population in 1850 was 1.2 billion i.e. 1200 million people. Through the early decades of the Industrial Revolution, life expectancy were low in Western Europe and the United States. Thousands of people died from infectious diseases such as typhoid and cholera, which spread rapidly in the crowded, filthy conditions that were common in early factory towns and major cities, or were weakened by poor nutrition. But from about 1850 through 1950, a cascade of health and safety advances radically improved living conditions in industrialised nations.