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Intermittent low-dose far-UVC irradiation inhibits growth of common mold below threshold limit value
Emilie Hage Mogensen1, Christian Kanstrup Holm1,2
1UV Medico A/S, Aarhus, Denmark.
Abstract:
Mold infestations in buildings pose significant challenges to human health, affecting both private residences and hospitals. While molds commonly trigger asthma and allergies in the immunocompetent, they can cause life-threatening diseases in the immunocompromised. Currently, there is an unmet need for new strategies to reduce or prevent mold infestations. Far-UVC technology can inactivate microorganisms while remaining safe for humans. This study investigates the inhibitory efficacy of far-UVC light at 222 nm on the growth of common mold-producing fungi, specifically Penicillium candidum, when delivered in low-dose on-off duty cycles, a configuration consistent with its use in real-world settings. The inhibitory effect of the low-dose duty cycles was assessed on growth induced by i) an adjacent spore-producing P. candidum donor and ii) P. candidum spores seeded directly onto agar plates. In both setups, the far-UVC light significantly inhibited both vertical and horizontal growth of P. candidum, even when the UV doses were below the Threshold Value Limit of 23 mJ/cm2. These results suggest that far-UVC light holds the potential to improve indoor air quality by reducing or preventing mold growth, also when people are present.
Insights
Far-UVC light effectively inhibits common mold growth, even at low doses. This technology shows promise for improving indoor air quality and preventing mold infestations in occupied spaces.
Area of Science:
- Environmental Health
- Microbiology
- Photobiology
Background:
- Mold infestations in buildings present health risks, from allergies to severe infections in immunocompromised individuals.
- Current strategies for mold prevention are limited, highlighting the need for novel approaches.
- Far-ultraviolet C (Far-UVC) light offers a promising method for microbial inactivation with proven human safety.
Purpose of the Study:
- To evaluate the efficacy of Far-UVC light in inhibiting the growth of Penicillium candidum, a common mold-producing fungus.
- To assess the impact of low-dose, on-off duty cycle Far-UVC irradiation on mold growth in simulated real-world conditions.
Main Methods:
- Investigated the inhibitory effects of 222 nm Far-UVC light on Penicillium candidum growth.
- Assessed growth inhibition using two setups: adjacent spore-producing donors and direct spore seeding on agar plates.
- Measured inhibition under low-dose, on-off duty cycles, including doses below the Threshold Value Limit (23 mJ/cm2).
Main Results:
- Far-UVC light significantly inhibited both vertical and horizontal growth of Penicillium candidum.
- Inhibitory effects were observed even at Far-UVC doses below the established Threshold Value Limit.
- The low-dose, on-off duty cycle application proved effective in controlling mold proliferation.
Conclusions:
- Far-UVC light demonstrates significant potential as a strategy to reduce or prevent mold growth in indoor environments.
- This technology can contribute to improved indoor air quality, even in the presence of people.
- Further application of Far-UVC technology may offer a safe and effective solution for managing building-related mold issues.
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