Polycyclic aromatic hydrocarbons are not a substance but a class. They are compounds built from two or more fused aromatic rings, formed whenever organic material burns incompletely. Nothing manufactures them for indoor use; they arrive as by-products of something being burned, charred or heated.
Polycyclic aromatic hydrocarbons are not a substance but a class. They are compounds built from two or more fused aromatic rings, formed whenever organic material burns incompletely. Nothing manufactures them for indoor use; they arrive as by-products of something being burned, charred or heated.
The class spans a very wide range of physical behaviour, and that range is why it is difficult to measure and easy to misreport. At the light end sits naphthalene, with two rings, volatile enough to behave as an ordinary volatile organic compound. In the middle sit the three- and four-ring compounds, which partition between vapour and particle phases depending on temperature and on how much airborne particulate is present. At the heavy end sit five- and six-ring compounds such as benzo[a]pyrene, effectively bound to particles and to deposited surface films rather than free as vapour.
Because of that spread, the phrase "PAH result" means little without a compound list. Two laboratories reporting the same air can produce very different numbers, simply because one summed a set of compounds and the other reported a single indicator.
The most consistent indoor source in the region is smoking, and shisha in particular. Charcoal-heated waterpipe smoke is generated by combustion of both the charcoal and the tobacco preparation, and it loads the room and whatever the extract system connects to with particulate-bound aromatic compounds. Conventional tobacco smoke contributes on the same pathway.
Cooking is the second, and in UAE food and beverage settings a major one. Grilling, charring and high-temperature frying pyrolyse fats and proteins directly, and shawarma grills, charcoal and open-flame cooking, mall food courts and hotel production kitchens run these processes for long hours. Where kitchen extract is undersized, poorly captured at the hood or discharged near a fresh-air intake, the products of that cooking re-enter occupied space.
Combustion plant and traffic form the third pathway, carrying the same compounds into basement and podium car parks and loading bays through generator and vehicle exhaust, and from there into occupied areas through lift shafts, stair cores and service risers. The fourth is site work: hot bitumen, torch-applied waterproofing and roofing operations release aromatic fume readily drawn into roof-level plant. The fifth is open-flame products used indoors — candles, incense and bakhoor, burned widely in homes, majlis areas, hotels and retail units across the region.
The controlling condition is the ventilation regime rather than emission chemistry. Envelopes are sealed and mechanically conditioned throughout the year, outdoor air fractions are held low to contain cooling load and recirculation is high, so smoke and cooking aerosol generated in one part of a building is redistributed rather than flushed, and windows are not opened through the long summer. The particle-bound fraction then behaves differently again, depositing onto soft furnishings, ceilings and duct interiors to form a reservoir that is re-entrained by cleaning and air movement long after the source event has ended.
The International Agency for Research on Cancer classifies benzo[a]pyrene as carcinogenic to humans, its highest classification, and several other individual polycyclic aromatic hydrocarbons carry lower IARC classifications as probably or possibly carcinogenic to humans. The evidence behind those classifications comes principally from occupational settings with heavy exposure to combustion products, rather than from ordinary building air.
Acute effects at indoor concentrations are dominated by the mixture rather than by the aromatic compounds themselves. Shisha smoke, cooking aerosol and exhaust all carry fine particulate, carbon monoxide, nitrogen dioxide and irritant carbonyls alongside the aromatics, and the eye, throat and airway irritation reported in smoky or poorly extracted spaces cannot be attributed to any single component. Isolating one substance from a combustion mixture is not defensible here, and the honest statement is that the exposure of concern is the mixture. Occupants with persistent symptoms should be directed to occupational health or a medical practitioner.
The WHO Guidelines for Indoor Air Quality: Selected Pollutants (2010) treat polycyclic aromatic hydrocarbons as one of their nine pollutants and decline to set a guideline concentration, publishing instead a unit risk for PAHs expressed as benzo[a]pyrene of 8.7 × 10⁻⁵ per ng/m³ for lifetime exposure.
Because the class straddles the vapour and particle phases, a single collection medium cannot capture it. Sampling requires a combined train: a filter to collect the particle-bound fraction, followed immediately by a sorbent — polyurethane foam, or polyurethane foam with XAD resin — to collect the vapour-phase compounds that pass through it. Both are extracted together and analysed by gas chromatography with mass spectrometry, the approach set out in EPA Compendium Method TO-13A. Sorbent tubes with thermal desorption under EPA Compendium Method TO-17 recover the light end of the class and miss the heavier particle-bound compounds, so a survey run on tubes alone should not be described as a PAH survey.
Table 4 of Dubai Municipality's Technical Guidelines for Indoor Air Quality for Healthy Life (DM-HSD-GU119-IAQ, Version 4, 11 December 2024) lists polycyclic aromatic hydrocarbons at 0.012 ng/m³ over 8 hours, under clause 9-8-6. Its status matters: under clause 9-8-9 that table operates as an alternative compliance route, applied where a sampling point fails the total volatile organic compound criterion, rather than as an objective tested at every point as a matter of course.
The entry names a class of many compounds and gives a single value, without stating whether it applies to a named indicator compound — benzo[a]pyrene is the usual convention internationally — or to the sum of a defined set, and without printing which compound list is intended. Naphthalene, the lightest member of the class, is treated separately in the same table at 10 µg/m³ over 8 hours and is covered on its own page.
For polycyclic aromatic hydrocarbons the Dubai Municipality route is indirect, which makes the status of the clause behind the total the operative point; it is set out in Regulation of indoor chemical contaminants in the UAE.
Source control comes first and is usually easy to identify, because the sources are activities rather than materials. Smoking and shisha areas should be physically separated from other occupancies with dedicated extract and a negative pressure relationship to adjoining space. Kitchen extract should be checked at the point of capture, since a hood that fails to capture at the grill face cannot be compensated for downstream, and its discharge position checked against every intake serving the building.
Increased outdoor air dilutes the airborne fraction but does not address the deposited reservoir, and in UAE summer conditions carries a cooling-load penalty that makes it unsustainable as a permanent control. Re-testing should follow under comparable activity and ventilation conditions, using the same method, compound list and reporting convention as the original survey.
Table 4 of Dubai Municipality's Technical Guidelines for Indoor Air Quality for Healthy Life (DM-HSD-GU119-IAQ, Version 4, 11 December 2024) lists polycyclic aromatic hydrocarbons at 0.012 ng/m³ over 8 hours, under clause 9-8-6. Its status matters: under clause 9-8-9 that table operates as an alternative compliance route, applied where a sampling point fails the total volatile organic compound criterion, rather than as an objective tested at every point as a matter of course. The figure needs care, and this is the most important point on the page. The entry names a class of many compounds and gives a single value, without stating whether it applies to a named indicator compound — benzo[a]pyrene is the usual convention internationally — or to the sum of a defined set, and without printing which compound list is intended. It is also expressed in nanograms per cubic metre where the rest of the table is in micrograms per cubic metre. Naphthalene, the lightest member of the class, is treated separately in the same table at 10 µg/m³ over 8 hours and is covered on its own page.
Dubai Municipality DM-HSD-GU119-IAQ Version 4 (11 December 2024), Table 4, clause 9-8-6 — polycyclic aromatic hydrocarbons 0.012 ng/m³ over 8 hours; naphthalene listed separately in the same table at 10 µg/m³ over 8 hours. The WHO unit risk for PAHs as benzo[a]pyrene of 8.7 × 10⁻⁵ per ng/m³ is not a limit and carries no averaging period.
Table 4 lists polycyclic aromatic hydrocarbons at 0.012 ng/m³ over 8 hours without naming an indicator compound or a compound list. The class contains many compounds, so a report must state whether it applied a single indicator such as benzo[a]pyrene or a summed set, and which compounds were included in it.
No. A photoionisation detector gives a total response weighted by response factor and identifies nothing. Sorbent tubes recover only the light, volatile end of the class. Polycyclic aromatic hydrocarbons need a combined filter and sorbent train with polyurethane foam or PUF/XAD, analysed by gas chromatography–mass spectrometry under EPA Compendium Method TO-13A.
No. The WHO Guidelines for Indoor Air Quality: Selected Pollutants include polycyclic aromatic hydrocarbons among their nine pollutants but publish a unit risk for PAHs as benzo[a]pyrene of 8.7 × 10⁻⁵ per ng/m³ rather than a guideline concentration. That supports a risk estimate, not a pass or fail, and WHO describes its guidelines as recommendations.