NEBOSH stands for “National Examination Board in Occupational Health and Safety. It is UK based independent examination board providing certification in health, Safety, and Environment. This course provides broader knowledge on risk management, health, and safety.
IOSH stands for “Institution of Occupational Safety and Health.” It’s professional health and safety membership forum, conducts training for managers, supervisor. This training will help managers to take appropriate action to handle practical situations.
Both NEBOSH and IOSH are relevant if you are looking for long term career in health and safety.
Now, let’s look at Six Sigma relevance.
Six Sigma is a data-driven methodology first introduced in the 1970s. Six Sigma is based on data analysis, hence helps in reducing risk which one of the many reasons that Six Sigma is still preferred over other improvement methodologies. The objective is to remove defects at the source and bring down performance to ‘six sigma’ level i.e. 3.4 defects for every one million opportunities. Continuous effort is made to achieve stable and predictable process.
Jack Welch made it the center of business strategy at General Electrical. In today’s competitive world, Six Sigma has widely accepted as a philosophy for growth across different sectors.
Six Sigma applies to all departments and industries. It has a very broad scope. So, professionals at all level are taking this course to improve day-to-day business and hence their performance.
Long answer short, my recommendation is you should go for Six Sigma course.