Tetrachloroethylene, more commonly called perchloroethylene or simply "perc", is a chlorinated solvent used above all as a dry-cleaning fluid. It is a colourless, dense liquid, non-flammable, and volatile enough to behave as an air contaminant indoors. Indoors, tetrachloroethylene behaves as an activity contaminant rather than a material emitter: it is not released by gypsum board, joinery, flooring or paint.
Tetrachloroethylene, more commonly called perchloroethylene or simply "perc", is a chlorinated solvent used above all as a dry-cleaning fluid. It is a colourless, dense liquid, non-flammable, and volatile enough to behave as an air contaminant indoors. That combination of solvency, chemical stability and non-flammability made it the dominant garment-cleaning solvent.
Indoors, tetrachloroethylene behaves as an activity contaminant rather than a material emitter: it is not released by gypsum board, joinery, flooring or paint. It appears because a process using it is operating somewhere connected to the building, or because something that has been through such a process has been brought inside.
Dry cleaning is the dominant source, and the UAE's building typology makes it unusually relevant. Dry cleaners and laundry units commonly occupy retail podium space beneath or beside residential and office floors, or sit in the retail strip of a mixed-use tower. That places a solvent operation inside the same structure as sleeping and working accommodation, connected by shared risers, service corridors, lift lobbies and basement car parks. Vapour escaping a machine, a still, a filter change or a transfer step does not stay in the unit; it follows those routes, and stack effect in a tall core can draw it upward.
Machine type and condition govern how much escapes. Older transfer arrangements, where garments move between a washer and a separate dryer, release considerably more than closed dry-to-dry machines with refrigerated vapour recovery, and maintenance, door seals, filter handling and waste storage all contribute. Solvent-contaminated waste and separator water left in a back-of-house area can continue to release vapour long after the machine has stopped.
Some spot removers, stain treatments and specialist degreasers contain tetrachloroethylene and are used in housekeeping and maintenance. Freshly cleaned garments and soft furnishings also carry residual solvent into the spaces where they are stored — a wardrobe, a hotel room or a store cupboard can become a slow secondary source for days after delivery, particularly where items are returned in sealed covers and hung immediately.
Sealed, mechanically conditioned envelopes and low outdoor-air fractions held down to limit cooling load mean high recirculation. A podium unit's solvent losses are not diluted away as in a naturally ventilated building; they are redistributed through whatever zone shares the air path.
Warm interior and plenum temperatures also raise evaporation from residues, waste containers and treated textiles, and pressure differences between the retail podium, the basement car park and the floors above set the direction of travel. Where the occupied floors are not held reliably positive relative to the podium and the car park, the transfer path runs the wrong way.
Acute exposure at the concentrations produced inside a poorly ventilated plant room during machine work causes eye, nose and throat irritation and central nervous system effects — headache, dizziness, drowsiness and impaired coordination. These are effects of direct occupational-scale exposure, not of the low residual concentrations that a neighbouring apartment or office would normally show, and reports should keep the two situations clearly apart.
The chronic position is more serious. The International Agency for Research on Cancer classifies tetrachloroethylene as probably carcinogenic to humans. Longer-term concerns also include effects on the liver, the kidney and the nervous system, with neurobehavioural findings at lower exposures still contested in the literature.
Most building complaints involve mixtures of compounds rather than a single substance, so symptoms cannot identify tetrachloroethylene as the cause on their own. Occupants or workers reporting persistent symptoms should be referred to occupational health or a medical practitioner rather than to an air-testing result.
Tetrachloroethylene is well retained on standard sorbents and is straightforward to determine by sorbent tube sampling with thermal desorption and a gas chromatography–mass spectrometry finish, under EPA Compendium Method TO-17 or ISO 16000-6:2021. Where several chlorinated solvents are in question, or where paired samples are needed across a podium unit, a lobby and an apartment, canister whole-air sampling under EPA Compendium Method TO-15A allows one analytical method to cover the set.
A photoionisation detector responds to tetrachloroethylene but reports a total response weighted by a response factor and identifies nothing. It is useful for walking a riser, a lobby and a car park to find where concentrations rise, but it cannot produce the figure an individual objective is compared against.
Table 4 of Dubai Municipality's Technical Guidelines for Indoor Air Quality for Healthy Life (DM-HSD-GU119-IAQ, Version 4, 11 December 2024) gives tetrachloroethylene 250 µg/m³ over eight hours, under clause 9-8-6. Table 4 operates as an alternative compliance route under clause 9-8-9, used where a sampling point fails the total volatile organic compound criterion. The standing of that objective is not the same in a new building as in an existing one, as Regulation of indoor chemical contaminants in the UAE explains.
Tetrachloroethylene is also one of the nine pollutants covered by the WHO Guidelines for Indoor Air Quality: Selected Pollutants (2010), which gives 0.25 mg/m³ on a year-long basis. WHO's guidelines have the character of recommendations and are not law in the UAE. These two figures deserve careful handling, because 250 µg/m³ and 0.25 mg/m³ are the same concentration expressed in different units — but they are attached to completely different averaging periods, one an eight-hour figure and the other a year-long one. A year-long guideline and an eight-hour objective are not interchangeable, and reporting a result against one while citing the other, or quoting either without naming its instrument and its averaging period, is precisely the error this resource exists to warn against.
Source control comes first. Where a dry-cleaning or laundry operation is identified, the response sits with that operation: machine type and condition, door and pump seals, filter and still-residue handling, waste and separator-water storage, and a dedicated extract discharging clear of any fresh-air intake. Where cleaned textiles are the carrier, airing delivered items in a ventilated area before they enter occupied space removes most of the residue. Sealing and pressure management of shared risers, service penetrations and lobby routes addresses the transfer path itself.
Ventilation is the second measure. Increased outdoor air dilutes a concentration but leaves the source in place, and in UAE summer conditions the cooling-load penalty makes it unsustainable as a permanent control. Re-testing should follow the intervention under comparable conditions — the same ventilation mode, the same operating pattern for the unit below, and the same sampling positions — so that a change can be attributed to the work rather than to a quiet day in the shop.
Table 4 of Dubai Municipality's Technical Guidelines for Indoor Air Quality for Healthy Life (DM-HSD-GU119-IAQ, Version 4, 11 December 2024) gives tetrachloroethylene 250 µg/m³ over eight hours, under clause 9-8-6. Table 4 operates as an alternative compliance route under clause 9-8-9, used where a sampling point fails the total volatile organic compound criterion. The objective takes its force from the clause behind it — Regulation of indoor chemical contaminants in the UAE. Tetrachloroethylene is also one of the nine pollutants covered by the WHO Guidelines for Indoor Air Quality: Selected Pollutants (2010), which gives 0.25 mg/m³ on a year-long basis. WHO's guidelines have the character of recommendations and are not law in the UAE. These two figures deserve careful handling, because 250 µg/m³ and 0.25 mg/m³ are the same concentration expressed in different units — but they are attached to completely different averaging periods, one an eight-hour figure and the other a year-long one.
Dubai Municipality DM-HSD-GU119-IAQ Version 4 (11 December 2024), Table 4, clause 9-8-6 — tetrachloroethylene 250 µg/m³ over eight hours. WHO Guidelines for Indoor Air Quality: Selected Pollutants (2010) — 0.25 mg/m³ on a year-long basis. The same concentration in different units, but not the same limit, because the averaging periods differ.
They are the same concentration in different units, but not the same limit. The Dubai Municipality Table 4 figure of 250 µg/m³ applies over eight hours; the WHO 2010 figure of 0.25 mg/m³ applies on a year-long basis. Both the instrument and the averaging period must be named whenever either is quoted.
It can. Shared risers, service corridors, stair cores, lift lobbies and basement car parks connect a podium unit to the floors above, and stack effect in a tall core can carry vapour upward. Whether it does depends on machine type and condition, extract arrangements and the pressure relationship between podium and occupied floors.
They can act as a slow secondary source. Residual solvent continues to leave garments and soft furnishings for some time after collection, particularly where items are returned in sealed covers and hung straight into a wardrobe. Airing them in a ventilated space first removes most of that residue.