What is the most required safety certificate?

That depends on the country you are at or what safety standard does the company follows. In UAE, NEBOSH certified safety practitioners are more demanded but there are some companies who are also looking for OSHA, IOSH trained safeties. But for me, dedication and commitment really counts.

NEBOSH has lost its credibility over time because they have proven to be unfair e.g. asking diploma level questions in certificate level exams, same almost same marks in recheck create a doubt on NEBOSH fairness. The only reason NEBOSH is still in the market is that there is no alternative to this certification in health and safety. I do not recommend NEBOSH IGC because it has fail rate of more than 80% and they do it intentionally just to prove that this certification is worthwhile. If you study their syllabus, you will be astonished that they have only copied/ paste it from RRC books. Its the time that some other certification backed by IOSH membership entitlement may be launched and you will see how NEBOSH increases pass percentage of students. 

Certified Health Safety Professional - Fire Safety Management (CHSP-FSM)

Occupational health & safety association

It depends on the country's Factory or Labor Laws and most of the countries in the world are complying the International Labor Organisation's law. I think, Nebosh certification which is helpful in achieving career growth in HSE field that covers ILO's requirements. However, as a HSE professional one should have highly motivation and inspiration to workforce on HSE matters with respect in implementing HSE objectives of the organisation. Waki Ahmed, HSE Advisor - Galfar Engineering

Without a doubt, its Nebosh. Go for it as this will open up the widest range of possibilities in safety field.

Hope that helps.

NEBOSH International General Certificate in Occupational Health and Safety

The most applied one Worldwide is (OSHA) Standards .

It depends on the place which you chose to work. As per my knowledge, in gulf NEBOSH, IOSH and OSHA is very important and mandatory for a HSSE Personnel.

NEBOSH INTERNATIONAL GENERAL CERTIFICATE (IGC)

Its all depends on your observation. This is the most important ability you need to work in EHS. It does not mean that you are a safety professional if you have a top most qualification in EHS.