Hi Ian

IOSH Magazine published this about a year ago.

Analysis: Survey reveals average OSH salaries in 2024 | IOSH magazine

To be honest, I don't think you can read that much into it, in particular due to the small sample and, even more so given the tiny proportion of those taking part in the survey who were NOT Members of IOSH.

The article attempted to draw conclusions that would not meet any test of being "statistically significant".

As example, 

‘It’s of interest that the mean salary of IOSH members was higher than that of non-members,’

....but followed immediately by the reason that not a lot can be taken out of a snapshot.....

‘though the sample size of the latter group was relatively small.

Despite this then spun into...

This demonstrates that being an IOSH member can have a positive effect on how you are paid as an OSH professional.’

It demonstrates nothing of the sort! It might be true.

Only about 3% of the respondents were NOT Members of IOSH - in total about 82 people who probably didn't include many e.g. structural and civil engineers involved in e.g. safety case roles.

Very clear to me that employers and employment agencies including those that purportedly specialise in EHS recruitment are generally not very well clued up as to working out how to define job responsibilities, match them up to person specs and then work out the market rate.