Their surrounding were killing them...

Scheele's Green was invented in 1775 by Carl Wilhelm Scheele.  The pigment was originally prepared by making a solution of sodium carbonate at a temperature of around 90 °C, then slowly adding arsenious oxide, while constantly stirring until everything had dissolved. This produced a sodium arsenite solution. In the 19th century the toxicity of arsenic compounds was not readily known. 19th century journals reported of children wasting away in bright green rooms, of ladies in green dresses swooning and newspaper printers being overcome by arsenic vapors. There is one example of an acute poisoning of children attending a Christmas party where dyed candles were burned.  During Napoleon's exile in St. Helena, he resided in a very luxurious room painted bright green, his favorite color. His cause of death is generally believed to be stomach cancer, and arsenic exposure has been linked to an increased risk of gastric carcinoma.