Why does a new home smell, and how long does it last?

Key facts

• In twenty renovated Dubai apartments, twelve exceeded the formaldehyde reference and ten exceeded the reference for volatile organic compounds.

  12 / 10 of 20 apartments Established

  Awad and Jung, Buildings 2021, measurements January to April 2020.

• Eighty percent of residents in those homes reported never or almost never experiencing symptoms.

  80 % Established

  Awad and Jung, Buildings 2021, resident questionnaire alongside the measurements.

• Volatile organic compounds fell below the reference level approximately thirty-six days after renovation.

  36 days Established

  Awad and Jung, Buildings 2021.

• Both volatile organic compound and formaldehyde concentrations were higher at higher relative humidity.

  Established

  Awad and Jung, Buildings 2021; formaldehyde against relative humidity, R squared of 0.373, p less than 0.01.

Why is formaldehyde separated from other volatile organic compounds?

Formaldehyde is separated from the general volatile organic compound measurement for two reasons. The first is toxicological: it is classified as a carcinogen, which places it in a different category from the broad mixture of solvents, alcohols and hydrocarbons that make up a total volatile organic compound reading.

The second is practical. Formaldehyde has a distinct and predictable source profile in buildings — urea-formaldehyde foam insulation, plywood, particle board and panelling, carpets and fabrics, glues and adhesives. These are structural and finishing materials rather than occupant-introduced products, which means the emission is a property of the building itself and persists on the building's timescale rather than the occupant's.

In the indoor index used in Dubai, formaldehyde carries a sub-index weight of 0.07 and volatile organic compounds 0.08, giving a combined 0.15.

How long does off-gassing last in a new or renovated home?

Off-gassing in a renovated home lasts weeks rather than days. A study of twenty renovated apartments at the Greens in Dubai, measured between January and April 2020, found that total volatile organic compounds fell below the reference level at approximately thirty-six days after renovation.

The severity depended on the extent of the work. Formaldehyde remained within the reference where renovation covered less than about 28 percent of the unit, and exceeded it where the work was more extensive — reaching 1.01 parts per million in one unit against a reference of 0.1.

A separate study of twelve new apartments applying World Health Organization methodology reported total volatile organic compounds at 2,634 micrograms per cubic metre, roughly nine times the local standard, alongside formaldehyde at 163 micrograms per cubic metre and toluene at 551.

Both studies are small, and the Greens work relied on direct-reading instruments giving instantaneous rather than integrated values on a single measurement day per unit. The direction and rough magnitude are consistent; the precise figures should be treated as indicative.

Why does the climate here make it worse?

The climate here works against off-gassing in two ways. Emission from materials is temperature and humidity dependent, and the Greens study found both volatile organic compound and formaldehyde concentrations were higher at higher relative humidity, with a statistically significant relationship for formaldehyde.

At the same time, the standard response to heat is to seal the building and cool it. A closed, air-conditioned apartment with no fresh-air path has a low air exchange rate, so whatever is emitted is diluted slowly.

The combination — elevated emission and reduced dilution — is close to the worst case. It also suggests a counterintuitive strategy: a warm, well-ventilated period drives emission faster and clears it, whereas a cool, sealed period suppresses the reading without removing the source.

What can a total VOC reading not tell you?

A total volatile organic compound reading cannot tell you which compounds are present. The measurement responds to a mixture and reports a single figure, so two homes with identical readings may have entirely different chemistry — one dominated by relatively benign alcohols from cleaning products, another by aromatic solvents. Formaldehyde in particular is not reliably captured and requires a dedicated sensor.

There is a second subtlety in how the guidance is written. The volatile organic compound bands in the technical guidance pair each concentration range with a tolerable exposure duration: the highest band is described as acceptable for hours, the next for under a month, the next for under a year. Exposure is dose multiplied by time, and a scale that encodes both is saying something a single threshold cannot.

Finally, the same metal-oxide sensing element used for volatile compounds is often used to estimate carbon dioxide in consumer devices. A device reporting both may be reporting one measurement twice.

Clear a newly renovated home

1. Ventilate hard for the first six weeksKeep the home ventilated continuously through the period when emission is highest.
2. Run it warm, not cool and sealedWarm and ventilated clears the source faster than cool and sealed, which only suppresses the reading.
3. Specify low-VOC materialsUse low-VOC paint, board and adhesives for any further work.
4. Keep solvents out of living spaceStore paints, adhesives and cleaning solvents outside the occupied envelope.

Definitions

Off-gassing

The release of volatile compounds from a material into the air after installation. In a renovated home it comes from board, adhesives, joinery and finishes, and it decays over weeks rather than days.

Total volatile organic compounds

A single figure summarising the response of a sensor to a mixture of volatile compounds. It cannot name what it found, so two homes with identical readings may have entirely different chemistry.

What we are sure of, and what we are not