What are the uses of naphthalene spheres

What is naphthalene? The canton chemist provides information

Interview: blog editor

The substance naphthalene was detected in two rooms at the canton school in Willisau, in school buildings in the municipalities of Lucerne, Ebikon, Kriens and Horw: The guideline values ​​for the tar-containing substance used in construction were exceeded in some cases, various measures such as binding ventilation planning and renovation were taken. But what actually is naphthalene? The canton chemist Dr. Silvio Arpagaus provides information.

What actually is naphthalene and what was it used for in construction?

Dr. Silvio Arpagaus: The older ones among us still know naphthalene from the mothballs, which used to contain this substance as the main active ingredient. In the meantime, however, naphthalene has largely been replaced by other, more effective and odorless substances. But naphthalene also occurs naturally. This is how it arises, for example, during combustion processes such as barbecuing or smoking.

Naphthalene is used on a large scale in the plastics industry. It is made from petroleum as well as from coal tar. Until the 1970s, tar-containing products were used in construction because of their water-repellent properties. These products, such as tar glue or tar paper, often contained naphthalene, which can lead to emissions even decades after installation.

What problems can the fabric cause?Is naphthalene especially harmful to children?

Animal experiments have shown that naphthalene can cause inflammation in the airways. If this persists over a long period of time, tumors can develop. For a case assessment, therefore, it is not just the concentration in the room air that is decisive, but also the duration of exposure, i.e. how long someone is exposed to these vapors.

According to the World Health Organization WHO, however, there is no reliable evidence of a possible carcinogenic effect in humans after inhalation exposure. For this reason, naphthalene is classified as a category 2 carcinogen, «suspected of causing cancer». In its studies, the WHO takes into account population groups that are particularly vulnerable due to their health status or age. They can therefore also be used to assess indoor air quality, for example in day-care centers, hospitals and old people's homes.


Why does this frequency occur now? Is there any connection with the hot summers of recent years?

Although higher naphthalene values ​​tend to be measured in polluted rooms with increasing temperature, we see no connection with the climatic changes. However, the reports of the last few months have certainly also raised awareness of this problem and increased pollutant measurements. In addition, today we are generally more critical of such air pollutants than in the past, when a naphthalene scent in the wardrobe was regarded as evidence of a well-run household.

Are there any other harmful substances in our school buildings and public buildings that are hidden in the building materials - such as asbestos or formaldehyde? If so: what is being done here?

Various fabrics were previously used in building for their beneficial properties. A well-known example is asbestos, which was used as a panacea in a variety of products in the 20th century. Only gradually did the health risks become known until asbestos was finally banned in Switzerland in 1990.

Measures like these are adapted to the individual case and the risk that exists for people and the environment. It is estimated that around 50,000 substances occur in living spaces and can lead to pollution.

What precautionary measures can be taken to reduce pollution? Do all school houses and buildings from this construction period now have to be renovated?

Pollutants come from various sources. The efforts to prevent or reduce their release must be correspondingly diverse. However, the inevitable loads in the room air can generally be reduced through consistent ventilation. This measure is also effective when exposed to naphthalene. Depending on the situation, however, further measures such as structural renovation measures, ventilation adjustments or the installation of room air filters must be taken.

The municipalities are responsible for monitoring residential hygiene and implementing measures against harmful emissions. The canton can support them in this task.

Naphthalene and formaldehyde: No valid limit values ​​in Switzerland

There are currently no statutory limits or guidelines for these two indoor air pollutants in Switzerland. Accordingly, the assessment is based on the guidelines of the World Health Organization (WHO), which specify a guideline value II of 30 µg / m3 for naphthalene. From this value on there is a need for action. It applies as an annual mean and not for a single exposure. In comparison, the occupational exposure limit (SUVA) is 1600 times higher.

Health consequences

Regardless of the WHO and BAG guideline values, the following applies as a precautionary measure: the lower the exposure, the lower the potential health risk. On the other hand, exceeding the guideline value does not mean an acute health risk. Further information regarding health risks: leaflet naphthalene, information formaldehyde BAG, WHO guidelines for indoor air quality