# Page:Popular Science Monthly Volume 81.djvu/397

The mill-workers are wet with the steam blown into the sheds, their clothes and bodies are moist, and the long hours of exposure to such uncomfortable conditions are most deleterious to physical vigor and happiness. The operatives asked that they might be allowed to work without steam-injectors and with diminished ventilation, so that the mill rooms became saturated with moisture evaporated from the bodies of the operatives. The old regulations, while forbidding more than 6 parts in 10,000 ${\displaystyle {\ce {CO2}}}$, put no limit to the wet-bulb temperature, and this often became excessive on hot summer days. The operatives were quite right. Less ventilation and a lower wet bulb is far better than ample ventilation and a high wet bulb. The permissible limit of ${\displaystyle {\ce {CO2}}}$ has now been raised to 11 parts in 10,000, and the wet-bulb temperature is to be controlled within reasonable limits.