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Technical update number 4. Soot (part one)

What is soot?

We all know it’s a black powder but few know what constituents make up the compound that we clean daily from the chimneys that we work on.

Soot is a by-product of the incomplete combustion of hydrocarbons. It is black because it contains carbon particles that have failed to burn.
Soot also often contains; fly ash, sulphurous compounds, nitrates, lead, formaldehyde, cyanide, and some real nasty polycyclic aromatic hydrocarbons these include; benzene, xanthalene, toluene, naphthalene and many others. These compounds are often referred to as VOCS or Volatile organic compounds.

Many of these VOCS  are now known to be carcinogenic and have been banned or reduced in diesel and petrol fuels. They are formed abundantly however burning nearly all hydrocarbon based fuels,( anything that started life as a tree or plant). Highest concentrations of VOCs can be found in oil flues followed by chimneys extracting the fumes from burning wood, particularly when the wood is too wet or if the air supply is limited so that moderate flaming combustion can not be maintained. The top section of chimneys often have high levels of dangerous compounds as gasses tend to cool and condensation takes place.

Soot cleaned from an open log fire

Soot cleaned from an open log fire

Health Implications for the sweep

You now know that soot contains compounds that are a danger to you. What you don’t know is that there are other risks, some of which I will explain in a limited fashion.

The carbon particles in soot are very small, they may be only. 2.5 microns in size and are often referred to as PM 2.5( there are 25,000 Microns in an inch). This is a concern because these tiny particles are difficult to filter with standard vacuums and masks meaning they can end up in your lungs. The really bad thing is that these tiny black balls are so small that they can pass through the mucus membrane in your lungs permanently blocking the air sacks and reducing function. This can lead to chronic infections, asthma, COPD, cancers and a myriad of other things.
The other major risk from soot is the exposure to the VOCs contained within. These compounds are found in low levels in a chimney so single exposure does not constitute a high risk, the major risk comes from repeated exposure that has a cumulative affect. These compounds are easily absorbed by the skin, lungs and mucus areas. They DO cause cancers.
Sweeping killed off all of the chimney boys, it’s 2018 not 1800 don’t be like them.

Personal protective equipment PPE

Always use appropriate PPE that covers all of the skin that comes into contact with soot.  If it’s too hot to wear proper PPE, then it’s too hot to go to work!.

Use barrier creams, layer gloves, cover your scalp it’s full of blood vessels, use proper sweeping coveralls or clothing,  invest in a really good mask and learn how to maintain and use it.

A quality full faced mask designed to work with a pump unit.

A quality full faced mask designed to work with a pump unit. Made by 3M

A mask pump unit

A 3m Jupiter mask pump unit


Exposure to soot and it’s compounds doesn’t stop after you have swept the chimney. Ensure that you thoroughly scrub your skin between jobs, reapply barrier creams, change clothing and gloves regularly throughout the working day. The less time you are exposed to VOCS the lower the risk will be. If you come home each day covered in soot then you are potentially at a higher risk of certain cancers and associated diseases than you need to be.

Change mask filters, check fit and clean regularly (there are courses available for masks we recommend you take one). Only masks with a P3 rating or higher should be considered for sweeping. Masks that are pump fed from a separate filtration unit with a helmet that covers the entire head and face offer superior protection when compared to traditional masks.
Keep your vehicle clean inside and out, separate a clean area and a dirty area and don’t cross contaminate them. Put dirty sheets in the dirty area and not back in the clean box for example. Make sure you have a bulk head separating you and the cab from the sooty tools and brushes behind.

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.

Who is at a higher risk?

Anyone who works with the by-products of combustion may be at risk and should do what is necessary to minimise these risks. These include but are not limited to:

Chimney sweeps, stove and fireplace Installers, solid fuel service technicians,  those working with bitumen EG roofers or tarmac layers, oil service engineers, those working with car exhaust repair,  anyone who regularly is in the vicinity of bonfires such as some farm workers,  people that work on and clean BBQs or wood fired pizza ovens and of course fire service personal.

Environmental implications

The emissions of fine dust from domestic appliances has become a major health concern in the U.K. and in many areas of the world. The air we breath often contains fine particles caused by incomplete combustion, primarily from Diesel engines but also from older wood stoves and oil appliances.
These particles are bad for us and everyone else too. It is in our interest as chimney sweeps to educate our customers on clean burning practices including; burning only high quality  dried logs and controlling their appliances to ensure that there is always enough air to allow moderate flaming combustion and that the fire is never slumbered.

Image thanks to the EPA. It shows just how small soot particles are.

I do hope that you absorb what is written here. We must look after ourselves in order that we can have long productive lives and that our advice helps others protect our planet so that our grand children can also. Although we have touched on health and safety we cannot cover the entire subject in one blog post as its vast, ensure you are up to date with health and safety practices for your trade.

There are various types of soot and chimney deposits these are cleaned in various ways using various methods. Make sure you read part two of this article so you stay in the know where we discuss ; soot types various cleaning methods and disposal