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We examine the photoinduced excited state dynamics of pyrene modified adenosine, a versatile probe for folding and hybridization of ribonucleic acids. Measurements in different solvents revealed complex ultrafast dynamics, but high robustness since the overall fluorescence quantum yield (Φf) is hardly affected. The result is a strong fluorescent RNA-probe whose spectral properties change in a defined way upon environmental changes.
Background: Particulate matter (PM) emission caused by tobacco combustion leads to severe health burdens worldwide. Second-hand smoke exposure is extraordinarily high in enclosed spaces (e.g., indoor rooms, car cabins) and poses a particular threat to the health of vulnerable individuals (e.g., children, elderly, etc.). This study aimed to establish a new measuring platform and investigate PM emissions under four different ventilation conditions inside a car cabin without exposing any person to harmful tobacco smoke.
Methods: PM concentrations were measured during the smoking of 3R4F reference cigarettes in a Mitsubishi Space Runner (interior volume 3.709 m3). The cigarettes were smoked with a machine, eliminating exposure of the researchers. Cigarettes were extinguished 4.5 min after ignition, and PM measurements continued until 10 min after ignition.
Results: High mean PM concentrations were measured for cigarettes without ventilation after 4.5 min (PM10: 1150 µg/m3, PM2.5: 1132 µg/m3, PM1: 861.6 µg/m3) and after 10 min (PM10: 1608 µg/m3, PM2.5: 1583 µg/m3, PM1: 1133 µg/m3). 3R4F smoked under conditions with turned on ventilation resulted in reduction of PM compared to those smoked without ventilation after 4.5 min (PM10:-47.5 to -58.4%, PM2.5:-47.2 to -58%, PM1:-39.6 to -50.2%) and after 10 min (PM10:-70.8 to -74.4%, PM2.5:-70.6 to -74.3%, PM1:-64.0 to -68.0%). Cigarettes smoked without ventilation generated high PM peaks at 4.5 min (PM10: 2207 µg/m3, PM2.5: 2166 µg/m3, PM1: 1421 µg/m3) and at 10 min (PM10: 1989 µg/m3, PM2.5: 1959 µg/m3, PM1: 1375 µg/m3). PM peaks of cigarettes smoked under different ventilation modes varied at 4.5 min (PM10: 630-845 µg/m3, PM2.5: 625-836 µg/m3, PM1: 543 - 693 µg/m3) and 10 min (PM10: 124 - 130 µg/m3, PM2.5: 124 - 129 µg/m3, PM1: 118 - 124 µg/m3).
Conclusion: The new measuring platform provides a safer way for researchers to investigate PM emissions of cigarettes. These data are comparable to published research and show that smoking in a parked vehicle with the windows closed generates harmful PM emissions even when the vehicle ventilation is in operation. Future studies should be carried out using the new measuring platform investigating PM exposure and PM distribution of in-vehicle smoking under a wide range of conditions.
Highlights
• An airport can result in high particle concentrations in a distant residential area.
• The particle size distribution indicated the airport as the main source of particles.
• Lower air traffic during the COVID-19 pandemic lead to lower particle concentrations.
• The particle concentration showed high temporal variations.
Abstract
Exposure to ultrafine particles has a significant influence on human health. In regions with large commercial airports, air traffic and ground operations can represent a potential particle source. The particle number concentration was measured in a low-traffic residential area about 7 km from Frankfurt Airport with a Condensation Particle Counter in a long-term study. In addition, the particle number size distribution was determined using a Fast Mobility Particle Sizer.
The particle number concentrations showed high variations over the entire measuring period and even within a single day. A maximum 24 h-mean of 24,120 cm−3 was detected. Very high particle number concentrations were in particular measured when the wind came from the direction of the airport. In this case, the particle number size distribution showed a maximum in the particle size range between 5 and 15 nm. Particles produced by combustion in jet engines typically have this size range and a high potential to be deposited in the alveoli. During a period with high air traffic volume, significantly higher particle number concentrations could be measured than during a period with low air traffic volume, as in the COVID-19 pandemic.
A large commercial airport thus has the potential to lead to a high particle number concentration even in a distant residential area. Due to the high particle number concentrations, the critical particle size, and strong concentration fluctuations, long-term measurements are essential for a realistic exposure analysis.