Atmospheric Pressure Change Measurement: An Observational Study

Introduction: The aim of the study was to show an atmospheric pressure change by indirect measurement in hermetically closed vessels during four years of follow-up. Methods: Study design: an observational study. In hermetically sealed elastic bottles with different liquids were measured differences in liquid and air volumes from baseline to nal follow-up period. The physical law of otation was used to measure liquid and air volume above liquid in bottles. To measure liquid and air (above liquid) volumes in each bottle was used the physical law of buoyancy. The follow-up period was four years. Results: The volumes of liquid and air in all bottles were decreased after the follow-up period to 14.38±2.40 and 36.25±3.37 ml, respectively. Air volume in comparison to liquid volume decreased more than two times signicantly (P=0.0007) after the follow-up period. Conclusions: Thus, atmospheric pressure increased during the last 4-year follow-up period. Further investigations are needed.


Introduction
Climate change observed in the worldwide in the last several decades. Global annually averaged surface air temperature has increased by 1.0°C over the last 115 years . (Wuebbles et al. 2017) Global warming since 1880 has followed a period of rapid acceleration in the past two decades. (National Centers for Environmental Information 2020) Database of NOAA's National Centers for Environmental Information evidences that hurricane activity in the world is increasing from 1851 to 2020. (NOAA's National Centers for Environmental Information & National Hurricane Center 2020) The 2018 U.S. National Climate Change Assessment reports that increase in greenhouse gases and decrease in air pollution have contributed to an increase in Atlantic hurricane activity since 1970.
Many other aspects of global climate are changing. For instance, changes in surface, atmospheric, and oceanic temperatures; melting glaciers; diminishing snow cover; shrinking sea ice; rising sea levels; ocean acidi cation; and increasing atmospheric water vapor. (Knutson et al. 2020) Nevertheless, a dynamic change in atmospheric pressure (AP) is presented incredibly rare. The aim of the observational study: to present a change in AP by indirect measurement of pressure in hermetically closed vessels for four years.

Materials And Methods
The observational study was conducted during four years (October 2016 -September 2020). Study objects: hermetically sealed eight elastic plastic bottles with different liquids: ve bottles with noncarbonated drinking water from various manufacturers (#1-5 bottles); one bottle chemical solvent "646" (#6 bottle); one bottle with drying oil (#7 bottle); and one bottle with alkyd varnish (#8 bottle) (see Table  1).
To reduce a diffusion coe cient for air and liquids the tested plastic bottles were stored for the years in a dark (no light) and cooled (18-20 o C) place.
The tested plastic bottles were not opened, not moved during the observational period.
Changes in the shape of the bottles were evaluated at a temperature of 24 о С.
Review questions: 1) was there an association between changes in AP and pressure in the tested bottles; 2) was there a trend in increasing in AP?
Due to the permeability of liquids and air through PET bottles, (Keller & Kouzes 2017) we measured liquid and air volumes before (baseline) and after ( nal) follow-up period.
To measure liquid and air (above liquid) volumes in each bottle was used the physical law of buoyancy, Archimedes' principle, stating that the volume of displaced uid is equivalent to the volume of an object fully immersed in a uid. (Randall et al. 2008) Statistical analysis. Two-tailed Student's t-test with Bonferroni correction was used. The study data are presented in Table as Mean (M), Standard Deviation (SD), and Standard Error of the Mean (SEM), where SEM is SD divided by the square root of the sample size. P-value <0.01667 was considered signi cant as a Bonferroni-corrected P-value (98.33%); n=8; the number of tests were performed = 3. Statistical analysis was performed using Excel-2013.

Results
All eight observed bottles gradually deformed towards attening during a not-opened four-year follow-up period (An appendix). Table 1 shows the volumes of liquid and air in all bottles that were decreased after the follow-up period to 14.38 ± 2.40 ml and 36.25 ± 3.37 ml, respectively. Air volume in compared to liquid volume decreased more than two times signi cantly (P=0.0007) after the follow-up period. Our study results showed indirect evidences of AP increasing during 4-year follow-up period based on the inverse relationship between changes in AP and pressure in the tested hermetically sealed bottles.

Discussion
AP and temperature, both of them are physical factors, which directly proportional in uence metabolic activity for every biological body on Earth. (Lopes et al. 2019); (Mota et al. 2020) In the world, in the same place, AP is also changing in the last few decades. (Bielec-Bakowska 2016) Over the study period , a minor increase in the annual air pressure values (0.17-0.32 hPa/10 years) was identi ed.
Increasing metabolic rate, in turn, increases biochemical reactions in the body. Possibly, the accelerating development of humankind relates to this phenomenon. A metabolic rate change depends on AP. Weight gaining in the total population also could be a result of the raised metabolism. Further investigations are needed.

Conclusions
The study showed that atmospheric pressure increased during four-year follow-up period based on the Ethics approval and consent to participate. Not applicable Consent for publication. Our manuscript does not contain any person's data in any form. All authors of the manuscript a rmed that they had access to the study data and reviewed and approved the nal manuscript.
Authors' contributions: KO: design and performance, literature analysis and review, bibliography review, data collection and interpretation, scienti c analysis, scienti c executor, writing, editing, and revision. GB: study design, re-writing the discussion, bibliography, and review. KM: study design, scienti c analysis, research review, print. AS: study design, research executor, editing, and revision. AT: re-writing the discussion, bibliography, research review.
Funding: This research did not receive any speci c grants from funding agencies in the public, commercial, or not-for-pro t sectors.
Declaration of interests: none. The authors declare that they do not have any competing interests ( nancial, professional, or personal) that are relevant to the manuscript. We have read and understood the journal policy on declaration of interests and have no interests to declare. Table 1 Liquid and air volumes in the eight bottles at baseline and nal of four-year follow-up period