Bioaerosol Property and Viability Affected by Various Environmental Factors

The monitoring of air pollution, especially the detection and characterization of biological aerosols (bioaerosols) in the atmosphere continues to be a challenging task. Most biosensors rely on the presence of specific molecules, such as antigens on the surface, DNA sequences, or the common fluorescents tryptophan, flavins, or reduced form of nicotinamide adenine dinucleotide (NADH). However, the de- tection signatures from either of these technologies can change significantly when the bioaerosol is released into the atmosphere, and the observed changes are strongly dependent upon the environmental conditions. In developing bioaerosol detection and characterization methods, researchers must account for the potential changes in their physical, chemical, and biological properties caused by various atmospheric conditions. The experimental results presented here show how the fluorescence spectral profile and intensity, the viability, and the PCR signature of bioaerosols, in particular for the vegetative bacteria Escherichia coli, change with time in the presence of one, or combinations of two, three, or four of the following variables: relative humidity <30% or ~75%, ozone ~100 ppb, α-pinene ~5 ppb, toluene ~45 ppb, and simulated solar ultra-violet light illumination with the typical levels in common atmospheric constituents and meteorological conditions. Large changes have been observed, e.g. UV fluorescence intensity dropped to be less than 1/10 of its initial value and the ratio of UV/visible fluo- rescence intensity flipped from 2 to ½ within 3 h. These changes could happen on a typical day in any city or suburban area. Recording data of the ageing processes measured here should be very useful in developing biosensors and monitoring air pollution.