Are the formaldehyde concentrations the same when the air is warm at 26 degrees in winter and cold at 26 degrees in summer?

Some time ago, we received a message from a fan friend: "Warm air at 26 degrees in winter and cold air at 26 degrees in summer, do the formaldehyde concentrations have the same value?"

The same also applies to:

"The temperature in my house is less than 25 degrees. Can I measure it directly?"

"I turned on the air conditioner to test it. Should I put a basin of water in the room?"

…

In order to help you solve your doubts, we won’t say much, but will just test it out!

View test conditions▼

Time: September 3 - September 16, 2021

Location: Inside the self-built experimental chamber of "Dad's Laboratory"

Experimental chamber conditions: area 12 ㎡, volume 30 m³ (about the size of a child's room), initial formaldehyde concentration

Formaldehyde release source: 9 pieces of 400 mm × 600 mm density boards (about the door panel area of ​​a 2 m high and 1 m wide double-door wardrobe)

Other interference sources in the cabin: None

Preparation before each experiment: Use fresh air at a ventilation rate of 80 m³/h (simulating window ventilation) until the formaldehyde concentration in the experimental chamber returns to the initial concentration, and then reseal it.

How much does temperature affect formaldehyde concentration?

We first tested the formaldehyde concentration under initial conditions (room temperature 28.2 ℃, humidity 51.7% RH) after being sealed for 24 hours, which was 0.295 mg/m³.

▲ Formaldehyde concentration when the test chamber temperature is 28.2 ℃ and the humidity is 51.7%RH

Keeping the conditions in the test chamber unchanged, we tested the formaldehyde concentration in the test chamber at 24 ℃ and 19 ℃:

▲ Formaldehyde concentration in the test chamber at three temperatures

From the graph we can clearly see that for every 4°C increase in temperature, the formaldehyde concentration will increase by nearly 100%!

In the past five years when we have been operating formaldehyde meters, the test data of more than 140,000 households have also proved that formaldehyde levels are most likely to exceed the standard in the hot and humid summer.

▲ "2020 National Home Environmental Protection Report" jointly released by Dad Review and Tsinghua University

There is one more thing we want to remind everyone, that is, the density boards used as the source of formaldehyde release in this experiment have actually been used by us for 2 years, and they can still cause the formaldehyde in the experimental chamber to exceed the standard by 3 times! You can imagine how terrible it would be if garbage density boards were secretly used at home!

Does humidity have such a big impact on formaldehyde concentration?

So if the temperature remains unchanged and only the humidity is changed, will the formaldehyde concentration change so much?

We tested the formaldehyde concentration under three humidity conditions at the same temperature (24 ℃):

▲ Formaldehyde concentration in the test chamber under three humidity conditions

It can be seen that when the humidity rises by about 10%, the formaldehyde concentration will increase by 0.5 times, which is smaller than the effect of temperature on formaldehyde concentration.

Then we can answer the question from the friend at the beginning.

Even if the temperature of warm air in winter and cold air in summer is the same, there will be differences in indoor humidity, and the formaldehyde concentration will naturally be different (generally speaking, the humidity in winter will be lower than in summer).

How should we respond?

From the experiment, we can see that temperature and humidity have a great impact on indoor formaldehyde concentration, and the impact of temperature is particularly great.

Therefore, we always recommend that you test at room temperature above 25°C. If you heat the room artificially during testing, the humidity may decrease, so be sure to humidify at the same time.

Of course, it does not mean that formaldehyde must be tested under high temperature and high humidity conditions. Whenever you are ready to move in, we recommend testing the formaldehyde in your home, which can make your family feel more at ease. Don't move in without testing and let your family breathe in formaldehyde without knowing it!

If you feel that this test did not reach a high temperature and humidity, you can retest it next summer and solve the problem in a targeted manner later.

In addition, during the test, we also found that when formaldehyde evaporates to a certain extent, the indoor formaldehyde concentration basically stops changing and reaches saturation. At high temperatures, this saturation speed is even faster!

▲ Formaldehyde concentration change trend under high and low temperature

This also further illustrates that when it is hot, don’t keep your home stuffy. Ventilate it more! Ventilate it more! Ventilate it more!

Well, this is the end of the popular science about formaldehyde. If you have any questions about formaldehyde, please leave us a message in the comment section!

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Source: Dad Review