WHO, NEA, and Singapore Air Quality Standards: Plain English

You will see references to “WHO 0.1 mg/m³” and “NEA guideline” in any IAQ test report. They sound technical but they are simple numbers, and knowing what they mean helps you read your own report and decide what to do. This is the plain-language version of the standards that matter for Singapore homes.

The 60-second answer

The most important number for indoor air is the World Health Organization (WHO) formaldehyde guideline of 0.1 mg per cubic metre of air, averaged over 30 minutes. That is the level above which most people start to feel symptoms (eye stinging, sore throat). Singapore’s NEA workplace guideline is similar. A new BTO bedroom in its first year often measures 3 to 10 times this level.

For homes, the question is not “is the level perfect” but “is it within the WHO guideline most of the time, and how vulnerable are the people sleeping there?”

What 0.1 mg/m³ actually means

Imagine a room that is 4 metres long, 4 metres wide, and 2.5 metres tall, a typical Singapore master bedroom. That is 40 cubic metres of air.

If the formaldehyde level is at the WHO guideline of 0.1 mg/m³, that means there is 4 mg of formaldehyde dissolved in the air of the entire room. Four milligrams. About the weight of a single grain of rice. Spread across 40,000 litres of air.

That tiny amount is enough to give a healthy adult mild eye irritation if they sit in the room for half an hour. Smaller amounts are fine; larger amounts cause noticeable symptoms.

This is why indoor air guidelines have to be precise. The difference between “fine” and “irritating” is a few grains of rice’s worth of chemical in a roomful of air.

ppm vs mg/m³: the unit confusion

You will see both in different reports.

• ppm (parts per million). Measures by volume. Out of every million parts of air, how many are the chemical?
• mg/m³ (milligrams per cubic metre). Measures by mass.

For formaldehyde at room temperature, the rough conversion is:

• 0.1 mg/m³ ≈ 0.08 ppm
• 1 ppm ≈ 1.23 mg/m³

Most Singapore reports use mg/m³. Some imported equipment and older reports use ppm. If you see “0.08” in your report, check which unit. 0.08 ppm is at WHO guideline; 0.08 mg/m³ is below it.

The WHO formaldehyde guideline

Set in 2010, still current.

• 0.1 mg/m³ over a 30-minute average. Above this, sensory irritation likely.
• The guideline is for the general population, including children and pregnant women.
• It is not a “safe” line and a “dangerous” line on either side. It is the level above which most people start to feel something.

There is no separate guideline for shorter or longer averages because formaldehyde reacts so quickly in mucous membranes that the 30-minute average captures the meaningful exposure.

NEA Singapore workplace guidelines

Singapore’s National Environment Agency has IAQ guidelines that apply to office and workplace environments, not residential.

• Formaldehyde: 0.1 mg/m³ (8-hour average for occupied workplace)
• TVOC: 0.6 mg/m³ (workplace; somewhat higher than the residential informal guideline of 0.3 to 0.5 mg/m³)
• CO₂: 1,000 ppm (proxy for ventilation adequacy)
• PM2.5: 35 µg/m³ (24-hour average; there are also shorter-term limits)
• Bacteria count: 500 CFU/m³ (in air sampling)

These are the numbers a workplace IAQ audit reports against. For homes, the WHO numbers are the more common reference because residential is unregulated.

How to read your own IAQ report

A typical Singapore residential report shows readings like this:

Room	Formaldehyde (mg/m³)	TVOC (mg/m³)
Master bedroom	0.18	0.75
Master wardrobe interior	0.42	1.4
Living room	0.08	0.35
Kitchen	0.12	0.55
Front door	0.03	0.15

How to interpret:

• Under 0.05 mg/m³ formaldehyde, under 0.3 mg/m³ TVOC. Safe for everyone, including infants and pregnant women.
• 0.05 to 0.1 mg/m³ formaldehyde. Within WHO guideline. Healthy adults fine. Vulnerable groups (pregnant, infant, asthma) should still aim lower.
• 0.1 to 0.2 mg/m³ formaldehyde. Above WHO guideline. Sensory irritation likely. Action recommended for any household.
• Above 0.2 mg/m³ formaldehyde. High. Treatment is the practical next step.

In the example above, the master bedroom is at 0.18 mg/m³ (above guideline) and the master wardrobe is at 0.42 mg/m³ (the dominant source). Treatment of the wardrobe interior would drop the bedroom reading substantially.

What about TVOC?

TVOC is the sum of volatile organic compounds other than formaldehyde. It is a useful indicator but less specific.

• Under 0.3 mg/m³. Low. Typical of older flats and post-treatment fresh flats.
• 0.3 to 0.5 mg/m³. Moderate. Common in flats 6 to 12 months post-renovation.
• 0.5 to 1.0 mg/m³. Above informal residential guideline. Symptoms likely.
• Above 1.0 mg/m³. High. Strong intervention needed.

TVOC and formaldehyde usually track each other but not always. A flat with high formaldehyde and low TVOC has a single dominant source (likely cabinets or floor adhesive). A flat with high TVOC and lower formaldehyde has paint or solvent residue rather than wood-based emission.

A practical decision tree

Once you have your readings:

1. Both formaldehyde and TVOC well below guideline. No action needed. Re-test if symptoms appear or new sources arrive.
2. Formaldehyde at or just above guideline, no symptoms. Continue daily ventilation, re-test in 4 to 8 weeks. Often resolves naturally.
3. Formaldehyde above guideline with symptoms, OR vulnerable household members present. Source-level treatment is the right call. Pre- and post-treatment testing confirms the change.
4. Both well above guideline. Treatment is the practical next step regardless of household composition.

For source-level treatment, see the formaldehyde and TVOC removal page. For what the test actually measures, see the IAQ test guide. For pregnancy- and infant-specific guidelines, see the pregnancy and indoor air guide and the bringing baby home checklist.

Sources

• World Health Organization. Guidelines for Indoor Air Quality: Selected Pollutants. WHO Regional Office for Europe, 2010.
• National Environment Agency, Singapore. Guidelines for Good Indoor Air Quality in Office Premises.
• Ministry of Manpower, Singapore. Workplace IAQ standards.
• ASHRAE Standard 62.1. Ventilation for Acceptable Indoor Air Quality.