The new LNS “Built Environment Microbiology” lab identifies exposure to indoor triggering agents: an effective tool in healthcare and in disease management

Patients’ indoor environment has become more and more associated with triggering and/ or exacerbating symptoms in many clinical conditions. Since November 2022, the new laboratory for the “Built Environment Microbiology” as part of the LNS Health Protection Department has been carrying out analyses of indoor environments in Luxembourgish households, as such contributing significantly to the life quality of patients and improving the health services system.

The new laboratory for the “Built Environment Microbiology”: a novel partner for Luxembourger physicians

The economic burden of respiratory diseases is one of the heaviest in Europe’s health services, mainly due to their chronic nature, frequent need for hospitalisation, and costly management. Many clinical conditions have been linked to the indoor environment causing symptoms to trigger or to worsen. Therefore, identifying environmental factors and improving indoor conditions represents a new and very efficient tool in managing respiratory diseases. With the LNS new laboratory for the “Built Environment Microbiology” becoming operational in November 2022, Luxembourgish physicians have become a new partner: The lab carries out microbiological analyses following medical prescriptions by general practitioners or specialist medical doctors, which may be related to, for example, persisting respiratory complaints or infections and investigations in immune-suppressed patients (e.g. cancer, transplantation). A team of nurses intervenes on site taking samples which are then analysed in the LNS lab. They work on the field day in day out, throughout Luxembourg to sample patients’ living or working environment for environmental analyses (air, surface…). A single “referent nurse” is assigned to each patient and takes care of the patient, answering any questions that may arise throughout the whole process. The Environmental Hygiene and Human Biological Monitoring Service is in charge of all the environmental samples (chemical and metal analyses and, since November 2022 the microbiological analyses via its new laboratory) as well as of the human biological samples for environmental and occupational toxicology.

Good service up-take by Luxembourg physicians and patients

The new lab for “Built Environment Microbiology” services have been widely embraced by physicians and patients in Luxembourg. Since January 2023, the lab has processed 524 air samples for mould and bacteria quantification, and mould identification, 42 surface samples for mould identification, 20 dust samples for allergen detection and quantification, and more than 200 samples for quality control purposes.

As an example, from first results, and based on 262 mould samples analysed, the indoor presence of moulds was on average 203 CFU/m³ ranging from 4 to 1828 CFU/m³. In microbiology, a CFU (colony forming unit) is the measure used to estimate the number of cultivable bacteria or fungal cells in a sample. Comparing to the outdoor, used as reference, an average of 190 CFU/m³ with a range between 24 and 732  CFU/m³ was detected. Higher indoor levels of moulds are usually associated with a prevalence of toxigenic moulds (Penicillium sp., and Aspergillus sp.).

Define methods and approaches for national needs in Luxembourg

Currently, the lab team has established methods for detecting bacteria, fungi, and allergens, quantifying and identifying indoor air, surfaces and dust. For the future, we will develop an inventory of the main species present in indoor environments in Luxembourg and from there outline techniques and strategies designed to address the specific requirements of Luxembourger patients at a national level.