Neat cutting oils are intended to lubricate, not cool. So they tend to get used for high pressure cutting applications such as gear shaping. Soluble oils provide cooling (due to the water) but not much lubrication. I use soluble oils when machining, but only with HSS tooling. Both brass and aluminium are turned dry. Personally I'd bin the cutting oil and turn dry to start with.

I have never worn a mask in the workshop and have never felt the need to do so. Neither do I have an extractor fan. The garage door isn't a close fit and that seems to be sufficient for air circulation.

Andrew

I'm surprised hobby quantity cutting oil is causing a problem, so maybe it's something else.

In the UK at the moment Hayfever, colds, and a new COVID variant are doing the rounds. (Don't panic, the COVID is a mild variant, only causing cold/flu-like symptoms and most of us are still vaccine protected.) And, rarely, some individuals are sensitive to the chemicals. Short or a rebreather, masks are unlikely to help because they catch particles, not fumes.

Unless a lot of hard cutting is done, cutting fluid may not be needed at all. Brass and cast-iron are cut dry, and I cut Aluminium with occasional brushed Paraffin, or sprayed WD40. Cutting fluid is reserved for threading, in tiny quantities.

The main purpose of cutting fluid is lubrication. It helps cool the tool too, but getting it too hot causes nasty fumes. In quantity, a flow of cutting fluid washes swarf away, so it isn't minced under the cutter.

For bulk cutting suds are often more useful than cutting fluid. Applied in quantity, suds cool and wash swarf away. Lubricates too, but that's secondary. Suds is an emulsion of a little soluble oil in water. Water is cheap and an extremely effective coolant. The soluble oil provides lubrication and prevents rust.

In the good old days suds was a serious health risk because nasty bacteria grow in soluble oil, and – before antibiotics – getting it in a cut could end in amputation or fatal sepsis. And it stinks. Modern suds contain disinfectants, but they don't last forever.

As flood-cooling is messy I avoid using it unless a lot of steel has to be machined. And carbide inserts reduce the need for cooling somewhat because carbide can be run hotter than HSS.

Industrially, mist systems are most likely to cause health problems, for which reason they are operated inside a sealed cabinet. Last time I read about it, industry (machine centres) seemed to be moving towards compressed gas systems. Something cold like liquid Nitrogen is sprayed accurately into the cut: the freezing gas blows swarf away and keeps the carbide cutter cool. There is no lubricant. A big advantage is it keeps swarf clean, greatly increasing the scrap value.

How much cutting fluid are you using. Try reducing it dramatically! As for advice if cutting back causes different problems.

Dave

People are affected differently by fumes and dust and solvents and may develop new allergies from time to time. A small fan through a tube to direct fresh air towards your face may help, and in summer it may be possible to get a flow in one end of the workshop and out the other.

Brass – no cutting oil and if possible have some special tools with very little top rake (look that up f you don't know) as it tends to dig in.
Aluminium. Try to cut dry but if the material starts to stick to the tool at the tip brush on a little of whatever oily stuff does not affect you. If that smokes because of the heat slow down. Kerosene/paraffin has been commonly recommended (main constituent of WD40) as it evaporates to also cool but that will mean more fumes. You could try wax, Lard and tallow were used in the past when oil was an exotic substance but that goes mouldy.
Steel. Try dry of with minimal oil brushed on. Slow down if smoke is coming off (not because the tool can't take it but because of your possible allergy). You can get away with almost no lubrication but it does often help the finnish on the very last cut.

BTW avoid bronze for a little while until you have some experience – it bites.

Keep it and use it for parting off, where it definitely helps

I use it & it does stink a bit. The smoke sometimes drives me out for a while. Luckily I have a door that can be left open. Don't bin it as it is great for threading. I have been using it for about 3 years with only my usual smokers cough.

Steve.

Steve beat me to it ! Do not bin it it will be good for taps and dies. or drilling. Noel.

Me neither – but I only use cutting fluids/coolants that are intended for the job. I never use the oft-recommended (here) WD40 since I can find no evidence that it's intended for that job and the MSDS makes no mention of it. Who knows what by-products are generated if it gets hot? (Not to mention it stinks).