Filtering the Fumes: Air Purifier Advice

Late last year, Cédric Van herck asked if BLAG members could recommend any air filters/purifiers for use in a poorly ventilated studio. And BLAG's science correspondent Jill Strong responded. (Also see Jill's previous article on lead paint.)

Activated Charcoal Filters

Working in a well-ventilated space is the best option, but if that's not possible then an activated charcoal filter (also called an active carbon filter) can make a massive difference.

Activated charcoal is the stuff used in water filters to take bleach and other undesirables out of tap water. It has between 600 and 1500 times more surface area available for trapping impurities than ordinary charcoal and Wikipedia rather delightfully likens the activation process to popping corn.

Activated charcoal can also trap gas molecules and that's what you need if you're working with signwriting enamels. VOCs (volatile organic compounds) are a group of liquids that evaporate easily; this makes them useful as solvents for fast drying paints. They often smell nice and also turn up in glues, lacquers and marker pens.

VOC Risks

VOCs are a diverse bunch of chemicals, both natural and synthetic. Some, like acetone, are deemed relatively safe; the main problem being that in high concentrations, they're a central nervous system depressant and might make you feel light-headed, start giggling, fall off a ladder, lose consciousness, or even imagine that Comic Sans is the best choice for a job.

Others, like benzene, one of the compounds which gives petrol its distinctive smell, are far nastier and come bristling with carcinogenic and teratogenic warning symbols. Either way, if you can smell them, they're getting into you body.

HEPA Helps

Activated charcoal filtration is a physical process where impurities get caught in the charcoal matrix and so when it's full, the filter stops working and must be changed. This is why most air purifiers have a two-stage process which also uses a HEPA filter.

HEPA stands for high-efficiency particulate air filter. They were invented in the 1950s to prevent scientists from inhaling radioactive particles during the Manhattan project and consist of a mesh of randomly arranged synthetic fibres which physically trap up to 99.95% of particulate matter above 0.3 microns. But they can't stop gases, which is why you also need the charcoal part. However, any dust, pollen, dog fluff, human skin cells, textile fibres, mould spores, sneeze droplets, fag smoke and bacteria floating around in the workshop won't get as far as clogging up the charcoal filter.

The HEPA/activated charcoal filter combination is very efficient and can be found in many stand alone air purification units, which are available in a range of sizes and prices.

Another option is a respirator mask with replaceable filters, and the one pictured below is a respirator with specific VOC filters. These too are very effective, but not everyone feels comfortable working in a mask.

A respirator mask is recommended for working with spray cans and other aerosols.

In Summary

Water-based paints applied with brushes and rollers don't pose much of a problem, but if you're using signwriting enamels or other VOCs, a stand-alone air purifier or a respirator can be useful, as long as you remember to change the filters regularly.

A respirator mask is recommended for times when you're spraying paint (airbrush, spray gun, paint cans), which leads to higher concentrations of VOCs in your working environment. And, as above, this type of work is best done where there is plenty of ventilation, ideally outside.

If you want to find out more about general air purification/build your own, check out this fascinating TED talk by Dr Thomas Talhelm, who decided to expose manufacturers of expensive stand alone units.

Written by Jill Strong

'That's All Folks!' (1971), Designer Unknown. First seen in the publicity for the Poster House exhibition, We Tried to Warn You! Environmental Crisis Posters, 1970–2020, which runs until 4 November 2024.

See Also

Why Lead Paint Makes Signs Last: A Toxic Legacy

An account of the enduring (and highly toxic) legacy of lead paint on signs, and sign painters.

BLAG Magazine: Adventures in Sign Painting Craft, Community & Culture •Better Letters