Bioaerosol

About: Bioaerosol is a research topic. Over the lifetime, 1347 publications have been published within this topic receiving 34791 citations.

Iron oxide nanowire-based filter for inactivation of airborne bacteria

Abstract: Heating, ventilation, and air conditioning (HVAC) systems are among the most common methods to improve indoor air quality. However, after long-term operation, the HVAC filter can result in a proliferation of bacteria, which may release into the filtered air subsequently. This issue can be addressed by designing antibacterial filters. In this study, we report an iron oxide nanowires-based filter fabricated from commercially available iron mesh through a thermal treatment. At optimal conditions, the filter demonstrated a log inactivation efficiency of > 7 within 10 seconds towards S. epidermidis (Gram-positive), a common bacterial species of indoor bioaerosol. 52 % of bioaerosol cells can be captured by a single filter, which can be further improved to 98.7 % by connecting five filters in-tandem. The capture and inactivation capacity of the reported filter did not degrade over long-term use. The inactivation of bacteria is attributed to the synergic effects of the hydroxyl radicals, electroporation, and Joule heating, which disrupted the cell wall and nucleoid of S. epidermidis, as verified by the model simulations, fluorescence microscopy, electron microscopy, and infrared spectroscopy. The relative humidity plays an important role in the inactivation process. The filter also exhibited a satisfactory inactivation efficiency towards E. coli (Gram-negative). The robust synthesis, low cost, and satisfactory inactivation performance towards both Gram-positive and Gram-negative bacteria make the filter demonstrated here suitable to be assembled into HVAC filters as an antibacterial layer for efficient control of indoor bioaerosols.

Instrumentation Used with Microbial Bioaerosols

Abstract: Bioaerosol monitoring is a rapidly emerging area of industrial hygiene that is finding increased use and overuse. It is often used in conjunction with indoor environment quality investigations, infectious disease outbreaks, and agricultural health investigations. Bioaerosol monitoring includes the measurement of viable (culturable and nonculturable) and nonviable microorganisms in both indoor (e.g., industrial, office, or residential) and outdoor (agricultural and general air quality) environments. In general, indoor bioaerosol sampling need not be performed if visible growth is observed. Contamination (microbial growth on floors, walls, or ceilings, or in the HVAC system) should be remediated. If personnel remain symptomatic after remediation, air sampling may be appropriate, keeping in mind that negative results are quite possible and they should be interpreted with caution. Other exceptions for which bioaerosol sampling may be appropriate include epidemiological investigations, research studies, or if indicated after consultation with an occupational physician and an immunologist.

Preliminary survey of indoor and outdoor airborne microfungi at coastal buildings in Egypt

Abstract: Forty six species and two sterile fungi and yeast species were isolated from samples collected both indoors and outdoors of coastal buildings located in an Egyptian coastal city. Twenty flats from ten buildings were investigated; children living in these buildings have been reported to suffer from respiratory illnesses. Samples were taken using a New Brunswick sampler (model STA-101) operating for 3.0 min at a flow rate of 6.0 l/min. Most of the species isolated have been associated with symptoms of respiratory allergies. Indoors the total culturable fungal count was 1548 CFU/m3; outdoors, it was 1452 CFU/m3. Indoor values of culturable fungal count, total spores count and ergosterol content ranged from 52 to 124 CFU/m3, 100 to 400 spore/m3 and 5 to 27.7 mg/m3, respectively, whereas outdoor levels typically varied between 25 and 222 CFU/m3, 110 and 900 spore/m3 and 3.3 and 67.2 mg/m3, respectively. The maxima for these parameters were detected indoors in house no. 6 and outdoors, outside of house no. 7. The most abundant species were primarily mitosporic (2832 CFU/m3). The most frequent species in both the indoor and outdoor samples were Cladosporium cladosporioides followed by Alternaria alternata and Penicillium chrysogenum,with inside:outside ratios of 1.4, 1.8 and 1.9, respectively. The patterns of fungal abundance were influenced to some extent by changes in the relative humidity and temperature. Other factors, such as type of culture media, rate of sedimentation, size, survival rates of spore and species competition,also affected fungal counts and should be taken into consideration during any analysis of bioaerosol data.