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Recent anecdotal and scientific reports have provided evidence of a link between COVID-19 and chemosensory impairments such as anosmia. However, these reports have downplayed or failed to distinguish potential effects on taste, ignored chemesthesis, generally lacked quantitative measurements, and were mostly restricted to data from single countries. Here, we report the development, implementation and initial results of a multi-lingual, international questionnaire to assess self-reported quantity and quality of perception in three distinct chemosensory modalities (smell, taste, and chemesthesis) before and during COVID-19. In the first 11 days after questionnaire launch, 4039 participants (2913 women, 1118 men, 8 other, ages 19-79) reported a COVID-19 diagnosis either via laboratory tests or clinical assessment. Importantly, smell, taste and chemesthetic function were each significantly reduced compared to their status before the disease. Difference scores (maximum possible change ±100) revealed a mean reduction of smell (-79.7±28.7, mean±SD), taste (-69.0±32.6), and chemesthetic (-37.3±36.2) function during COVID-19. Qualitative changes in olfactory ability (parosmia and phantosmia) were relatively rare and correlated with smell loss. Importantly, perceived nasal obstruction did not account for smell loss. Furthermore, chemosensory impairments were similar between participants in the laboratory test and clinical assessment groups. These results show that COVID-19-associated chemosensory impairment is not limited to smell, but also affects taste and chemesthesis. The multimodal impact of COVID-19 and lack of perceived nasal obstruction suggest that SARS-CoV-2 infection may disrupt sensory-neural mechanisms. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This work was supported financially with discretionary funds from the Pennsylvania State University (Penn State), including a gift from James and Helen Zallie g

Malodors, odors perceived to be unpleasant or offensive, may elicit negative symptoms via the olfactory system’s connections to cognitive and behavioral systems at levels below the known thresholds for direct adverse events. Publications on harm caused by indoor malodor are fragmented across disciplines and have not been comprehensively summarized to date. This review examines the potential negative effects of indoor malodor on human behavior, performance and health, including individual factors that may govern such responses and identifies gaps in existing research. Reported findings show that indoor malodor may have negative psychological, physical, social, and economic effects. However, further research is needed to understand whether the adverse effects are elicited via an individual’s experience or expectations or through a direct effect on human physiology and well-being. Conversely, mitigating indoor malodor has been reported to have benefits on performance and subjective responses in workers. Eliminating the source of malodor is often not achievable, particularly in low-income communities. Therefore, affordable approaches to mitigate indoor malodor such as air fresheners may hold promise. However, further investigations are needed into the effectiveness of such measures on improving health outcomes such as cognition, mood, and stress levels and their overall impact on indoor air quality.

The goal of our research program is to construct an electronic olfactory system (enose) that has the sensitivity, intelligence and discriminative capability of the mammalian olfactory system, as exemplified by a trained sniffer dog. We aim to create both the sensor array front end and the pattern analysis and learning back end. Our criteria for success include rapid and reliable detection of trace gas signals from both humans and ordinance. We have developed a novel sensor technology based on DNA-decorated single-walled semiconducting carbon nanotubes arrayed as the semiconductor elements in field effect transistors (Gelperin and Johnson, 2008; Johnson et al., 2009). A diagram of our sensor is shown in Figure 1. Our strategy is to broaden and deepen our understanding of the ability of this new sensor technology to respond to and discriminate between odorants while simultaneously developing the pattern recognition and machine learning techniques to process sensor array data. Our progress in these areas will be presented in three parts dealing with sensor development, odor sampling with a commercial sensor array, and algorithm development., The original document contains color images. Prepared in collaboration with University of Pennsylvania Depts. of Physics & Astronomy and Electrical & Systems Engineering.

Troops deployed in the Persian Gulf War were exposed to an unusually diverse mix of odorous chemicals at the same time as they were exposed to physiological and psychological stressors B a scenario that research in animal models suggests will lead to the development of specific conditioned responses. The goal of this research is to investigate the extent to which people can acquire stress reactions as conditioned responses to odors and exhibit health symptoms as a result of such conditioning episodes. Thus, the paradigm investigated in this project can serve as a model system for examining and understanding the persistent symptom constellations found in GWS and other stress-mediated syndromes. Results from the first three studies strongly suggest that odor-stress conditioning can powerfully mediate elevations in hormonal status (salivary cortisol) self reported stress, health symptoms and judged cognitive effort on memory tests, and that cognitive information about the nature of the chemical odor may enhance the stress and health symptom reports over that which is due to conditioning alone. Current studies are continuing to explore additional parameters of the odor-stress conditioning paradigm., The original document contains color images.

Troops deployed in the Persian Gulf War were exposed to an unusually diverse mix of odorous chemicals at the same time that they were exposed to physiological and psychological stressors, a scenario that research in animal models suggests will lead to the development of specific conditioned responses. The goal of this research is to investigate the extent to which people can acquire stress reactions as conditioned responses to odors and exhibit health symptoms as a result of such conditioning episodes. Thus, the paradigm investigated in this project can serve as a model system for examining and understanding the persistent symptom constellations found in Gulf War Syndrome (GWS) and other stress-mediated syndromes. Results from the first three studies strongly suggest that odor-stress conditioning can mediate elevations in hormonal status (salivary cortisol), self-reported stress, health symptoms, and judged cognitive effort on memory tests, and that cognitive information about the nature of the chemical odor may enhance the stress and health symptom reports over that which is due to conditioning alone. Current studies are continuing to explore additional parameters of the odor-stress conditioning paradigm., Prepared in collaboration with the Monell Chemical Senses Center, Philadelphia, PA.

Troops deployed in the Persian Gulf War were exposed to an unusually diverse mix of odorous chemicals at the same time as they were exposed to physiological and psychological stressors B a scenario that research in animal models suggests will lead to the development of specific conditioned% responses. The goal of this research is to investigate the extent to which people can acquire stress reactions as conditioned responses to odors and exhibit health symptoms as a result of such conditioning episodes. Thus, the paradigm investigated in this project can serve as a model system for examining and understanding the persistent symptom constellations found in GWS and other stress-mediated syndromes. Due to delays in the approval of the protocol for human research participation, the brief period of time during which we have been able to test human research participants has limited the conclusions that can be drawn at this juncture. However, preliminary results suggest that odors paired with a stressful situation subsequently elicit negative responses when experienced alone This finding, if supported, has considerable relevance to understanding symptoms that occur in deployment situations, typified by exposure to stressors experienced in the presence of novel odors.