What are Polycyclic Aromatic Hydrocarbons? PAHs
Polycyclic aromatic hydrocarbons are groups of organic chemical compounds formed from the combustion or decay process of Hydrocarbon fuel (wood, coal peat etc).
There are over 100 known PAHs. Some occur naturally and are even thought by some to be an intrinsic factor in the beginning of all life and evolution due to their mutagenic properties.
Polycyclic aromatic hydrocarbons are colourless, white or pale yellow-green solids.
They can be evaporated and gaseous depending on heat and weight. PAHs are often very happy to bond with carbon particles such as those within our soot.
Both The world health organisation and the EPA have isolated and labelled several PAHs as cell mutagens and likely causes for several human cancer types.
PAHs are found in abundance in wood and some coal soot, in the worst-case scenario 10% of the entire chemical mixture that we are exposed to can be these volatile compounds. Even in the best-case scenario 2% or more of wood soot will be PAH meaning that 10 kg of soot will contain at least 200 grams of a group of products known carcinogens. That’s a lot, scary stuff aye.?
Benzopyrene is one well studied PAH found in wood combustion residue they are harmful because they form carcinogenic and mutagenic metabolites (such as (+)-benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide from benzo[a]pyrene) which intercalate into DNA, I note Benzopyrene specifically at some studies show it to be 20 x more mutagenic than other PAHs.
Some studies have shown that over 12 PAHs are typically produced and as many as 25 different types of PAHs can be found at the same time during wood and coal combustion, what’s worse is that even those compounds in the mixture which are none mutagenic independently can for synergistic relationships with other compounds which can have mutagenic affects.
Chimney Sweeps EXPOSURE
The primary method of exposure to chimney sweeps is via inhalation, however PAHs are quite happy to be absorbed via the skin and mucus membranes too. A combination of inhalation and absorption greatly increases exposure levels and the risk of cancers and associated illnesses.
While the world health organisation is concerned primarily with airborne release of PAHS and the affect they have on general populous. We that is us sweeps will be exposed to extremely high levels by comparison and must take job specific contamination extremely seriously.
It is our responsibility to ourselves, our clients and our families to ensure that we manage these risks using every tool available and following best practice with PPE and RPE on every job.
Hundreds of UK chimney sweeps die prematurely each year from work related illness, the HSE published figures that show 60 poor souls die some years from work related oesophageal cancer alone.
What else contains these compounds that may add to a sweep’s exposure?
- Cigarette smoke and smoking
- Roasted coffee
- Smoked or Barbequed food
- The air we breath
- Oils and tars
- SOOT particles, Carbon particles of between 2.5PM and PM10 are a well know and studied fine dust carcinogens and causes of lung diseases. Soot is this fine dust in concentrated form!
There a few things a sweep can do to help reduce exposure and risk of developing associated illness and cancers. I will list some.
- Avoid any exposure!
- Always work within your capabilities
- Work to a risk assessment
- Always use Category 111 Type 5/6 disposable suit. bags/dispose of them after each job, they’re not reusable items.
- Ideally use a PAPR HEPA rated TM3 respirator on every job, keep it clean, serviced and replace filters as needed. Always store your respirator in a clean area.
- A PAPR Full faced hood type respirator fitted wit a PR-SL + nuisance level organic gas cartridge is best practice as the face and head are completely covered and therefore better protected. High efficiency Particulate Respirator filters with additional nuisance level organic vapor or acid gas relief are specifically recommended due to the particulate polycyclic aromatic hydrocarbons contained in the soot matrix.
- Get a proper face fit for your RPE where required
- While it is stated that some PAPR system can give 500x OEL protection, Some respirators will only protect concentrations of 20X or 40X the occupational exposure limit. Find out what the OEL is for various PAHS and PM 2.5s/ PM 10s and don’t exceed it. Half masks only protect for up to 20x OEL for a maximum of 1 hour!
- Seal and encapsulate fireplace opening or stove with disposable 1000-gauge poly where possible
- Use clean sheets on every job
- Only use H rated vacuums. Keep them clean, replace bags and filters regularly and have them DOP tested 6 monthly, when airflow is restricted or every 500 chimneys or whichever is sooner.
- Use a H rated air cleaner on any dirty job and leave it running for 30 minutes after you have cleaned away and finished. Not great in the real world sure, but its best practice.
- Use barrier creams and gloves
- Wash with soap and water after every job, duration time is important in reducing absorption.
- NEVER wear dirty work cloths in the cab of your van!
- Use disposable nitrile gloves under your work gloves and throw them after every job
- DO NOT eat or drink in the working area, you will ingest nasties and you can’t do either while wearing your respirator
- Double bag and goose neck/tape seal soot at source and dispose of it professionally
- Regularly visit the steam room, it will help clean the skin and help the lungs clear some particles
- Visit and pay for an HSE approved occupational doctor every 2 years.
The purpose of this article is not to scare sweeps or to shock but to educate and inform.
If, however a little fear does motivate you into a safer work practice then that’s fine for us too.
We have a very odd situation in the UK where sweeps will spend thousands on cleaning equipment’s but be completely unaware of the compounds that they are cleaning, volatising and breathing in! Hopefully articles such as this will encourage a rethink and reprioritising of equipment, training and exposure control strategies.