Naphthalene in indoor air

The project

Location: Property department of a major Swiss city
Phases: Repurposing of an existing building with naphthalene contamination in the indoor air
Period: From 2019


An old multi-storey building in a major Swiss city was to  be repurposed. When planning the renovation work, one of the participants noticed an unpleasant chemical smell. Chemical analysis of the indoor air showed that it was strongly polluted with naphthalene.
Naphthalene is a bicyclic carbohydrate with a characteristic smell of moth repellent / tar and is often present in construction products containing tar or in heated natural insulation materials. Naphthalene is classified as potentially carcinogenic by the World Health Organisation (WHO) and, even at low concentrations, can cause headaches, nausea and concentration problems in building users. The naphthalene sources therefore needed to be removed before this building could be repurposed. Ecosens AG was tasked by the city’s property department with identifying the sources and developing a remediation plan, including a cost estimate. Our survey showed that the strongest naphthalene source in the building was a chaff layer in the intermediate floor that contained tar (see image).


Our services

  • Creation of a complete hazardous material report for the building (incl. asbestos and PCB).
  • Identification of all building materials containing naphthalene.
  • Assessment of the risk to future users following successful remediation to support decision-making for the renovation work.
  • Planning of the hazardous material remediation and derivation of a realistic remediation target.
  • Compilation of a cost estimate for the remediation of hazardous materials in the building.


  • Considerable communication demands, in particular regarding current users
  • Testing and analysis of a multitude of potential naphthalene emitters to determine the main source
  • Performance of model calculations regarding the feasibility of the remediation target
  • Extensive clarification with remediation companies to identify effective remediation methods

Project manager:

Pascal Diefenbacher Divisional manager for indoor air quality
Dr. sc. Environmental Sciences (Federal Institute of Technology) +41 44 839 47 97 More