When it comes to post-fire restoration, one of the major factors is smoke and odour. Omar Al Hadrami, President, Smart Solutions – in this two-part series on smoke and odour restoration – outlines the various issues and hazards of smoke and odour after the outbreak of a fire.

In the case of a major outbreak of fire, the fire maybe extinguished, and the fire trucks may be gone, but without proper immediate response, the real damage and the costs are just beginning. To return residential or commercial properties to their pre-loss condition, it is important to have professionals work on the restoration. It is certainly not a job for a do-it-yourself property owner.

The Institute of Inspection Cleaning and Restoration Certification, recommends hiring a certified restoration firm. Restoration to a property can be complex. Proper smoke and odor removal are tasks that require technicians certified in these specific areas.

Components of Smoke

For an idea of the various tasks, let us break down the results of a fire. The first is smoke. Smoke has various components in it that must be treated specifically.

1. Gases

These are vapours and not visible components. Gases generated in a fire are noxious to individuals directly exposed to the smoke while the fire is in progress. After the fire is extinguished and the smoke dispersed or evacuated, the gases cease to be a significant factor. People are often concerned about toxic gases during the restoration process. Toxic materials are most likely to be released into the air during construction. We are more concerned with airborne particulates, which we may be breathing during the restoration process. Utilising a respiratory protective device, air scrubbing equipment or ventilating the structure will reduce the health risks of airborne particulates.

2. Aerosols

In addition to gases, smoke also consists of finely divided particulate matter and suspended liquid droplets known as aerosols. When a carbonaceous substance is burned, it releases carbon in combination with various tars, acids, resins, etc. This sticky residue aided by heat, magnetism and impingement, builds up on surfaces and creates areas of odour. Should this residue settle into areas that lack air movement, it creates pockets of odour. This occurs under the conditions of incomplete combustion normally present in fires. A phenomenon is that the soot residue is odourless, but because of its high carbon content, it has absorbed highly odorous material onto its surface. It is this absorbed odour, which causes olfactory offence. Therefore, smoke is then defined as the airborne solid and liquid particulates and gases produced when a material undergoes partial combust

Smoke particles

The relative size of the smoke particulate we are dealing with is 0.1- 4 microns (1 micron = 1 thousandth of 1 millimeter; 1 millionth of 1 meter; or 1 twenty-five thousandth of 1 inch). The size, quantity and character of the smoke particulate and aerosols produced by a fire depend on the following items:

1. Nature of the material

The various materials consumed by a fire influence the type of particulates and aerosols produced. Dry wood, paper and other natural fibres tend to produce a small non-smearing residue/particulate. Plastics, foam rubber and similar polymers produce large easily smeared particulates.

2. Rate of combustion

Fires are frequently categorized by the rate of combustion, which depends on the amounts of available oxygen. Oxygen-rich fires burn rapidly and produce smaller smoke particles resulting in more complete degree of oxidation, often termed as ‘dry smoke’. Oxygen-starved (smouldering) fires produce larger particles and have a less than advanced degree of oxidation and are often termed as ‘wet smoke’.

Effects of contamination

As earlier stated, a burning structure and its contents produce literally thousands of different gases, all of which fall into two different categories:

1. Oxides of Nitrogen produced by

organic compounds such as oil, food, paper, wood, etc., and most common in fires.

2. Sulphur Dioxide produced by inorganic compounds such as plastics, rubber, etc.

Smoke residue (soot) commonly comprises carbon and oxides of nitrogen. An additional by-product of incomplete combustion is polycyclic aromatic hydrocarbons (PAH); coupled with soot, they are classified as carcinogenic. When these chemicals, now in the form of soot residue, settle on furnishings and fixtures, they rapidly combine with humidity in the air or with moisture that has been introduced by the fire departments, to form two types of acids - Nitric Acid and Sulphuric Acid. The continuing effect of the contamination in disaster situations is a result of water and acid soot residues. The severity of the soot contamination will also increase with an increase in temperature and penetration, prolonged combustion time (duration of the fire), amounts of available oxygen or lack thereof, and finally, increased oil contamination in the soot.

Ongoing damage

The following describes the ongoing effects of acid soot residues on various structural and content surfaces generally found within the building environment:

1. Within the first day

Water contamination spreads to unaffected areas, office contents may stain a floor covering permanently; moisture sensitive surfaces may turn white; paper goods are ruined due to moisture absorption and swelling. Acid soot residues, within minutes, may cause discoloration (yellow) of plastic surfaces; rapidly cooling hot oils, combined with soot residues, form a difficult-to-remove film on surfaces; due to heat, some surfaces may expand and entrap the soot residues.

2. Within 2-3 days

Machines in direct contact with water begin to delaminate, rust, and legs may begin to stain (breakdown); bacterial odour starts to becomes apparent. In the presence of acid soot residues, metals tarnish; counter tops yellow; appliances yellow (especially those extending above the heat line); parts discolour.

3. Within 4-7 days

In the presence of moisture, mould and mildew appears along with a characteristic ‘musty’ odour; moisturesensitive internal components begin to swell; metal surfaces begin to rust; door and window casings swell, distort or delaminate. In the presence of acid soot residues, painted walls yellow permanently; metal corrodes and pits; wood furniture requires refinishing; linoleum floors require replacement.

4. Within the first 2 weeks

Mildew associated with prolonged dampness sinks its roots into organic materials such as jute, paper, panelling, wood, etc. Acid soot residues cause carpet fibres - synthetic in particular - to yellow permanently; silver plates corrode permanently; glass, china and crystal require replacement due to severe etching and pitting caused by prolonged exposure to the acids. Smoke-damaged flooring and structural materials (salvageable) should be cleaned at the beginning and again at the end of the restoration project. The key here is to neutralise the acid soot residue as quickly as possible in order to ‘mitigate’ the loss. Contents, for this same reason, do not have the luxury of waiting until the structural repairs may be determined or commenced.

NOTE: The ability to effectively restore soot-contaminated surfaces is dependent on whether the soot is oily or dry and the amount of moisture present.

The second half of this article – outlining smoke residue and smoke behavior will be published in the next issue of Clean Middle East

About the Author: Omar Al Hadrami is the President of Smart Solutions Cleaning Services. He is an Emirati citizen and the first certified Arab in his field. Over the past 8 years, he has received training from reputed institutions from across the world including IICRC Las Vegas USA and the first IICRC certified firm in the Middle East. He is also considering a course on Asbestos Removal and Hazardous Waste Management from the UK. Al Hadrami evangelises disaster recovery cleaning and is passionate about imparting his knowledge in the trade of specialised cleaning techniques.