A chainsaw, a leaf blower or a petrol brushcutter are machines regulated at three levels that have nothing to do with one another: engine emissions, noise output, and the conditions of use set locally. Mixing the three up leads to some persistent myths — the most widespread being: "petrol is about to be banned".
Here is what actually applies, and what it changes on the ground.
1. Engine emissions
The small engines fitted to garden and forestry machinery fall under the rules covering non-road mobile machinery. Those rules set emission limits by engine category and by power band, and they bite on the placing on the market of new machines.
What that means in practice:
- Manufacturers have moved their two-strokes wholesale to stratified-scavenging designs, which sharply cut unburnt hydrocarbons — hence modern engines that run leaner and are often harder to tune the old-fashioned way.
- Carburettors increasingly come with limiter caps on the adjustment screws, or are electronically managed, precisely to prevent a re-tune that would take the machine outside its approval.
- A machine already in service is not caught retroactively: it stays perfectly usable.
The point that matters for the owner: a badly serviced engine falls outside the limits it was approved against. A clogged air filter richens the mixture, a sooted-up exhaust raises back pressure, a worn plug degrades combustion. Emissions and fuel consumption go up, power goes down.
2. Noise: the LWA marking
This is the most visible part and the most misunderstood. Equipment intended for outdoor use carries a regulatory marking of the guaranteed sound power level, written LWA and expressed in decibels, inside a dedicated pictogram on the machine. British rules on outdoor equipment noise require the same marking, so the figure on the housing means the same thing whether the machine was bought here or elsewhere in Europe.
Two things not to confuse:
- LWA (sound power): what the machine puts out overall. It is the marked figure, the one used as the regulatory reference. It sits somewhere around 105 to 118 dB for a domestic petrol chainsaw.
- Sound pressure at the operator's ear: what the user is actually exposed to, a lower number, but the one that drives the need for hearing protection. It's in the handbook.
LWA is used as a criterion in public tenders, in leasehold and estate management rules, in some local authority specifications and, increasingly, in local restrictions. When buying, it's a figure you can genuinely compare — the gap between two models of the same power can reach 4 to 6 dB, which is a very audible difference.
And an obvious point too often forgotten: hearing protection is a legal duty on the employer's side and strongly advised for everyone above the exposure limits. A chainsaw sits well past the level at which prolonged exposure damages hearing irreversibly.
3. Hours of use and restrictions
This is where most neighbour disputes sit, and it's the least harmonised level of the three.
There is no single national rule fixing mowing or chainsaw hours. The general framework is noise nuisance law, enforced by your local council, which publishes its own guidance on acceptable hours and acts on complaints. The permitted windows vary from one council area to the next, typically tighter on Saturdays and much tighter on Sundays and bank holidays.
Two consequences:
- The only reliable source is the guidance in force where you live, on your council's website or by phone.
- A lease, an estate covenant or a management company's rules can be stricter than the council's guidance.
On top of that, in some areas, come restrictions tied to dry spells and wildfire risk: using petrol tools capable of throwing sparks can be banned during the day for certain periods. These measures are seasonal and local — you check them at the moment you're about to work, not once and for all.
Finally, some councils have restricted the use of petrol blowers on their own land or by their contractors, often on an LWA threshold. Those decisions are local and do not amount to a general ban.
