As a 14 year old summer council jobber..
I used to have to drag 5 litres of petrol round with me for the strimmer (stihl) the spark for these was often knacked, filters had to be cleaned in a splash of petrol
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& in terms of balance a petrol can meant walking distance back & forth a lot, I used to dream of li-batt strimmers.
In terms of noise, a lot safer for the user not just the environment, staying alert whilst no outside sound beyond the machinery itself was a devil.
No H&S as such, & luckily I was a teen with a bit more nous than some (farm work) so didn't get the dressing downs & ridicule of the others.