Effect and evaluation of odours at indoor workplaces

Project No. IFA 3144


completed 06/2020


Odours in indoor areas often prompt complaints and lead to workers being concerned for their health. Measurements of hazardous substances in indoor atmospheres, and evaluation of the results against guideline and reference values, are often ineffective as a strategy against odours because many substances causing odours cannot be detected, for example by analytical methods.

Indoor air measurements and a survey of workers in offices with no known indoor air problems were to be conducted. These were intended to yield comparative values for offices free of indoor air problems, and also correlations between reported health complaints and the actual exposure to hazardous substances.

In cases where complaints of odours are raised, the comparative values obtained are intended to support assessment of whether the frequency of complaints is unusually high or within the normal background prevalence. These comparative values can supplement the recommended procedure of the report: Indoor workplaces: recommended procedure for investigations into the working environment. This enables the German Social Accident Insurance Institutions to adopt a uniform procedure for determining and assessing complaints concerning air quality at indoor workplaces and the efficacy of the measures taken.

At the same time, the measurements of volatile organic compounds (VOCs) and aldehydes conducted in the project enabled the new measurement strategy of the MGU (measurement programme 9124 – indoor measurements in accordance with the measurement strategy for office workplaces) to be further improved.

The project was conducted jointly by the Institute for Occupational Safety and Health of the German Social Accident Insurance (IFA) and the Institute for Prevention and Occupational Medicine of the German Social Accident Insurance Institute of the Ruhr University Bochum (IPA).


A questionnaire for the survey and assessment of air quality at indoor workplaces was developed and applied, and the results evaluated. The survey conducted in offices without known indoor air problems enabled the frequency of complaints concerning the indoor climate to be determined, health complaints identified and information on perceived odours and their nuisance obtained. Parallel to the surveys, measurements of VOCs, aldehydes and CO2 and measurements of air temperature and atmospheric humidity were carried out to determine whether impairments were caused by unfavourable climatic conditions or exposure to harmful substances in the office workplace atmospheres.

The measurements were taken in accordance with the guidance for measurement programme of the German accident insurance institutions – indoor measurements in accordance with the measurement strategy for office workplaces. The VOC and aldehyde measurements were taken under both equilibrium and usage conditions.

This project was limited to office workplaces. Different types of offices of differing occupancy (e.g. two-person office, open-plan office, new building, older building) were considered.

Project schedule:

A pre-test conducted in 2016/2017 at the IPA reviewed the questionnaire and the feasibility of the surveys. In a subsequent internal preliminary study, approximately 100 questionnaires were distributed in offices at various DGUV sites, and indoor measurements carried out there at the same time.

From 2017 to 2019, a total of 131 office workers at member companies of the German Social Accident Insurance Institutions were interviewed in the main study, and 116 indoor measurements taken at the same time. The original goal of the study, i.e. for 500 to 1,000 questionnaires with accompanying indoor measurements to be completed in order for a representative body of data to be obtained covering the full range of buildings, office sizes, weekly working hours, etc., was not achieved, despite strong support by the accident insurance institutions.


Interior measurements:

All CO2 values lay between 549 and 3,294 mg/m³. The recommended CO2 value for usage conditions of 1,800 mg/m³ (1,000 ppm) was exceeded in 28% of the offices. The TVOC values lay between 0.05 and 0.97 mg/m³. The recommended TVOC value for usage conditions of 1 mg/m³ was not exceeded in any measurement. In addition to the TVOC values, the values of 68 individual VOC and aldehyde substances were also determined. The individual substances were assessed against the indoor guidance values RW I (precautionary value) and RW II (hazard value). The test shows that only the RW I value was exceeded, for a few specific substances. In no case was the RW II value exceeded. Together with the elevated CO2 values, these values indicate inadequacies in the ventilation arrangements.

Allowing for the different seasons, the measured air temperature and relative atmospheric humidity values are typical for indoor workplaces in Germany.


Following the plausibility check (8 questionnaires) and review of the exclusion criteria, 75 completed questionnaires of a total of 131 were evaluated. Exclusion criteria were exceeding of the recommended CO2 value under usage conditions of 1,800 mg/m3 (26 questionnaires), complaints of unacceptable air quality or significant odour nuisance (15 questionnaires), and a working time of ≤ 15 hours per week (7 questionnaires).

The respondents' assessment of their working conditions was predominantly positive: 76 % found their work interesting and stimulating and 89 % were able to complete their work during working hours. However, the majority (73 %) wished to be able to influence the indoor climate directly. With the exception of the atmospheric humidity, this was possible for over 90% for the room temperature, window ventilation and lighting conditions.

In offices with no known indoor problems, noise is the most frequently mentioned nuisance factor of the working environment at 13 %, immediately followed by dry air at 12 %. The most frequently stated health complaints include fatigue at 15 % and headaches at 9 %.


The willingness to participate in the survey was significantly lower than expected. Reasons for this included:

  • The concern that employees would be overtaxed by too many surveys in the year
  • The difficulty of finding offices with no indoor problems whatsoever, e.g. high temperatures in summer due to direct sunlight

A comparison both with reference data from Sweden (Andersson, 1998) and with recent studies of the frequency of health complaints in the wider German population (Hinz et al., 2017) reveals close correlation with the results of the study.

Owing to the poor representativeness, comparison with the data used as a reference can provide only an initial orientation assessment of whether an above-average number of workers complain of impairments or whether a pattern of complaints is evident. Nevertheless, the study results suggest that a complaint rate of over 20 % can be considered elevated.

The results of the project are to supplement the DGUV Report: Indoor workplaces: recommended procedure for investigations into the working environment. The standardized questionnaire can be used to gather relevant information, from the workers' point of view, in a structured form. This yields an initial assessment of the possible causes of the complaints and enables the further study steps, possibly costly, indicated by the results of the study to be planned efficiently. Were the questionnaire to be used in the future to elucidate problems at office workplaces, the reference data gathered in this project could be continuously expanded by additional surveys in comparison rooms, i.e. in offices without known problems associated with indoor spaces.

Last Update:

19 Oct 2020


Financed by:
  • Deutsche Gesetzliche Unfallversicherung e. V. (DGUV)
Research institution(s):
  • Institut für Arbeitsschutz der Deutschen Gesetzlichen Unfallversicherung (IFA)
  • Institut für Prävention und Arbeitsmedizin der Deutschen Gesetzlichen Unfallversicherung - Institut der Ruhr-Universität Bochum (IPA)

-cross sectoral-

Type of hazard:

work-related health hazards


health impairments and disorders, indoors, interior

Description, key words:

indoor workplaces, reference values, odours, air quality, health complaints


Further information