Removal of Odorants in Nursing Homes Using Air Cleaners

This project aims to enhance the odor environment in laundry and linen rooms in nursing homes. The problem arises from the storage of soiled laundry in these rooms for several days before it is collected or washed, leading to the release of odorants. This often causes discomfort for both staff and residents, as the odors can spread to hallways and adjacent spaces. Aarhus Municipality intends to investigate whether this issue can be fully or partially resolved by installing air purifiers in the rooms.
Adsorption, specifically activated carbon, was selected as the primary technology for odor removal among the technologies utilized in air purifiers. Photocatalytic oxidation (PCO) was selected as a secondary focus area. Seven different air purifiers (6 with active carbon, 1 PCO) were selected for further testing in the laboratory. These tests were performed using acetaldehyde, as an indicator of odor, and a reduction in concentration ranging from 19% to 83% after 20 minutes was measured for the six products utilizing activated carbon. However, the product solely relying on PCO did not show a significant effect.
Degassing from the air purifiers with activated carbon filters was also examined in the laboratory and here it was found that all six products re-emitted acetaldehyde after the efficiency test. The degassing of captured acetaldehyde into the surrounding environment counteracts the intended effect and is, therefore, important to investigate. Additionally, five out of seven tested air purifiers emitted traces of other gases, characterized as byproducts, which were identified by an increase in the concentration of specific substances during testing compared to the reference experiment without an air purifier turned on. These byproducts may result from the conversion of one gas to another potentially more harmful substance. However, the concentrations of all identified byproducts were significantly lower than the instated guidelines.
Four nursing homes were chosen to have an air purifier installed in one of their linen/laundry rooms. The concentration of total volatile organic compounds (TVOC) was continuously measured throughout the project period using air quality sensors in laundry rooms at each of the four selected nursing homes. TVOCs are used here as an indicator of odor concentration.
It has been challenging to draw a conclusive statement about the effectiveness of air purifiers on odors, as numerous peaks in TVOC concentration occurred frequently, probably due to the presence of ethanol in the air, caused using hand sanitizers. This significantly influenced the sensor data, potentially overshadowing the contribution from odor compounds in the measurements that often smell even in very low concentrations.
Overall, the project has indicated that the used air purifiers can reduce the concentration of odor compounds, in the form of TVOC, at the four selected locations. The results show the most apparent effect during periods when the average TVOC concentration was highest. In these time periods, the TVOC concentration generally became lower than in the period without the air purifier. However, the average TVOC concentration is not consistently lower at the four nursing homes during the period with an air purifier installed compared to the period without.