Crown Eco Jakarta Capital Management asking what is the best boiler system to install, which is safe to human health?

The operation of boilers in buildings must be done in a safe and environmentally acceptable manner. Safety issues include control of water level and overpressure. Environmental issues include restrictions on sewering boiler blowdown. Indoor air quality issues include the use of amines in steam used for humidification~ sterilization and food preparation. Control of feed water and boiler water quality is a factor in both safety and environmental considerations.

What is the best boiler system to install, a boiler which is safe to human health and to the environment? I want the air-ventilation inside safe for me and my family. And also I want a cost effective boiler that will last.