Burning scented candle with lavender on the right, air-Q air meter on the left against a brown background

Test measurements

air-Q Lab field test: How unhealthy are scented candles?

In our Halloween special, we got to the bottom of the question: Whether scented candles and co. can be harmful to health, even carcinogenic. We have now measured the extent to which burning candles change the quality of indoor air. The results are available here.

Author:

Undine Jaehne

Date:

3.11.2023

Scented candles quickly conjure up a cozy atmosphere, but with the sweet scent also spread harmful substances. In our separate article, we took a closer look at the risks and looked for healthy alternatives. Since we wanted to know exactly, we simulated the effects in a self-test and recorded them with our air-Q air measuring device.

Scented candles in the air-Q test: pollutant development in the room air

We investigated how the use of scented candles affects the room air. For this purpose, we started a practical experiment in a room of about 22 m². Before we lit the commercially available scented candles (Ikea tea lights with fragrance), we aired the room briefly. When the relevant measurement data showed a good starting point, we lit the 5 scented candles around 9:15 pm. We placed two candles directly next to the air-Q air meter and three others on a table. We let the experiment run until 11 pm.

Test results carbon monoxide development by scented candles

Graphic air measurement air-Q measured value carbon monoxide — The use of scented candles increases the level of carbon monoxide in the room

The sensor for carbon monoxide reacted clearly while the scented candles were burning. Shortly after the test began, the reading rose constantly: from an initial 0.7 to around 1.3 μg/m³. This represents an increase of 85.7 percent. The average carbon monoxide content in the room was 1.05 μg/m³. Scented candles therefore constantly extract oxygen from the room and enrich it with carbon monoxide.

Test results fine dust pollution from scented candles

Graphic air measurement air-Q measured value particulates — The air-Q measuring device detected fluctuating fine dust values

The particulates values also changed during the test period. In contrast to carbon monoxide, the value did not rise steadily, but showed a continuous alternation of rising and falling values. The initial value was always exceeded. The air-Q detected both large particulate matter (PM₁₀) and fine components (PM₂,₅), both particle sizes behaved similarly. While a minimum of 6 to 7 μg/m³ was readable at the beginning, the values kept increasing and reached a peak of 26 to 28 μg/m³ around 22:50. Accordingly, the particulates values increased by 300 percent.

Test results VOC exposure from burning candles

Graphic air measurement air-Q Measured value VOC — Scented candles release VOC

Already at the beginning of the test period, the measured values of volatile organic compounds (VOC) rose from 29,000 to 60,000 ppb within a few minutes. This represents an increase of 106.9 percent compared to the initial value. Thereafter, the air-Q showed relatively constant values on a plateau at about 60,000 ppb. After about an hour, the VOC levels dropped again, so that toward the end of the test, the VOC level was about 35,000 ppb - still a 20.7 percent increase over the baseline value. The average level was 51,738 ppb.

Test results nitrogen dioxides in indoor air due to scented candles

Graphic air measurement air-Q Measured value nitrogen dioxide — The burning of scented candles releases nitrogen dioxides

The pollutant nitrogen dioxide, which can exacerbate asthma and allergies, also increased significantly during the test: from 19 to 62 µg/m³. Initially, the value rose in a constant curve, peaked shortly after 10 p.m., and then flattened out slightly - to around 55 µg/m³. The recommended limit value is 40 and is thus exceeded by the scented candles by about 1/3. Despite a slight drop in the maximum value, the exposure did not fall below the limit value again.

Conclusion

Scented candles have a noticeable effect on indoor pollution levels. In addition, a long-term effect over several hours can be demonstrated. This shows that the decorative objects are a source of pollutants. In addition to particulates, VOC and nitrogen dioxide, the fragrances they contain can impair health as well as performance and even cause or intensify allergies. With an air meter like the air-Q you can detect the pollutants in your rooms and find out when limit values are exceeded. Thanks to the intuitive LED traffic light and the detailed evaluations, you will know when it is time for an air exchange in the room and which air pollutants are floating in the air.