High Ambient Relative Humidity Research Articles

Changes in rectal temperature as a means of assessing heat tolerance and sensitivity in chickens

High ambient temperature and relative humidity significantly affect growth and production performance in poultry. Ability of poultry to regulate their core body temperature relative to the ambient temperature depends on the relative nutrient/energy expenditure in maintenance and performance requirements. We hypothesized that changes in rectal temperature corrected for surface area can be used as a measure of heat tolerance/sensitivity. Rectal temperatures of one hundred mixed sex Ross 308 broiler chickens were measured hourly from 6 AM to 6 PM at 24 days of age. The ambient temperature and relative humidity were also measured hourly for the same 12-h period. Body weights were measured at day 24 and 38 days of age. The temperature-humidity index (THI) increased from 77.5 at 6.00 AM and peaked at 83.5 at 3.00 PM. The average rectal temperature increased from 39.900C at 6.00 AM to about 41.300C at 9.00 AM. Thereafter, the average rectal temperature remained constant until 3.00 PM when it began to decline. At 6.00 PM, the rectal temperature had declined to about 40.70 °C. Evaporative heat loss is affected by surface areas and as a result, rectal temperature was corrected for surface area. The change in rectal temperature corrected for surface area was negatively correlated with body weight gain indicating variability in the response of individual chickens exposed to similar THI. This variability was attributed to heat tolerance. It was hypothesized that mismatch between nutrient and energy supply and the partition of nutrient/energy between maintenance of core body temperature and protein synthesis could be reflected on the differences in heat-tolerance and body weight gain in the chicken population. The genetic basis of differences in rectal temperature changes corrected for surface area could be elucidated as a means of developing thermo-tolerant chickens.

Exacerbation of Hepatic Damage in Endothelial Aquaporin 1 Transgenic Mice after Experimental Heatstroke.

Heatstroke induces fluid loss and electrolyte abnormalities owing to high ambient temperature (AT) and relative humidity (RH). Aquaporin 1 (AQP1) is a key protein for water homeostasis; however, its role in heatstroke remains unclear. This study examines endothelial AQP1 in Tie2-Cre/LNL-AQP1 double transgenic (dTG) mice with upregulated Aqp1 in endothelial cells. For experimental heatstroke, mice were exposed to 41 °C AT and >99% RH. Blood, brain, kidney, and liver samples were collected 24 h later. Blood was analyzed for electrolytes and tissue damage markers, and organs were examined using morphological and immunohistological staining for 3-nitrotyrosine (3-NT), AQP1, and Iba-1. No difference in Aqp1 expression was observed in the whole brain; however, it was detected in dTG mice after capillary deprivation. AQP1 immunostaining revealed immunoreaction in blood vessels. After heat exposure, wild-type and dTG mice showed electrolyte abnormalities compared with non-heatstroke wild-type mice. Hepatic damage markers were significantly higher in dTG mice than in wild-type mice. Hematoxylin-eosin staining and 3-NT immunoreactivity in the liver indicated hepatic damage. The number of Iba-1-positive cells adherent to hepatic vasculature was significantly higher in dTG mice than in wild-type mice. This study is the first to suggest that endothelial AQP1 contributes to hepatic damage after heatstroke.

Comparison of hermetic and conventional bags for maize seed preservation in Azad Kashmir, Pakistan

Maize (Zea mays L.) is a major cereal crop used as a staple food worldwide for decades. Farmers store their produce in porous polypropylene bags under humid conditions which negatively affects their quality. In this study, maize seeds were stored in hermetic and conventional bags with an initial seed moisture content of 13.5% (wet basis) and 96.3% germination for 8 months at four major maize growing districts (Athmuqam, Hattian Bala, Muzaffarabad and Rawlakot) of Azad Jammu and Kashmir, Pakistan. Due to high ambient relative humidity conditions (>80%), an increase in moisture was observed in seeds stored in porous conventional bags (14. 7%). This increase was because of high initial relative humidity conditions (79–85%) in conventional bags. Seed moisture content remained unchanged in hermetic bags and internal humidity was 59–60%. As a result of hermetic conditions, germination and seed integrity were maintained in hermetic bags compared to conventional woven bags. Germination drastically decreased in conventional bags and fell to 9 % (Athmuqam), 13 % (Hattian Bala), 11 % (Muzaffarabad) and 12 % (Rawlakot). Higher physical quality losses of maize in conventional bags were because of infestation activity of live insect pest populations (S. zeamais, R. dominica and T. castaneum) that initiated 21.7–23.7 % weight loss in polypropylene bags. Hermetic bags protected seeds from insect pest attack and maintained seed quality. Higher contamination of aflatoxin B1, G1, B2 and G2 (ppb) was recorded in seeds stored in conventional bags as compared to hermetic bags. Aflatoxin B1 was maximum in conventional bag at Hattian Bala (8.93 ppb) followed by Muzaffarabad (6.68 ppb), Athmuqam (5.02 ppb) and Rawlakot (0.71 ppb). In conclusion, the use of hermetic dry chain storage preserves maize seed quality and thus can have a significant impact on the livelihoods of smallholder farmers of humid areas.

ESD Research of SCR Devices under Harsh Environments.

In prior technology, system-level electrostatic discharge (ESD) tests under environment change conditions mainly focused on testing the effect of a high-temperature environment. i.e., the effect on internal circuits of heat generated outside. However, few studies have explored the effect of ambient relative humidity changes on integrated circuits (ICs). Therefore, this study will analyze the performance of various ESD protection components under high ambient temperature and high ambient relative humidity. The ESD protection devices are tested for the ESD robustness of the silicon-controlled rectifiers (SCR) under a harsh environment and the measurement results are discussed and verified in the CMOS process.

Flaw recognition in reinforced concrete bridges using infrared thermography: A case study

Infrared thermography is a non-destructive test that is increasingly used in the inspection of existing buildings, bridges, and civil works. However, its practice is limited due to the influence of environmental conditions on the results of the test. The present study aims to evaluate the methodology of the test through the inspection of existing reinforced concrete bridges in Recife, Brazil. This city presents different environmental conditions from those reported in the literature, a high ambient temperature and relative humidity. The study comprises the inspection of five bridges in two days, analyzing their superstructure and infrastructure separately. The results show that flaw recognition is possible through the temperature gradient between imperfect and intact regions. Thus, variation in temperature greater than 0.3 °C allows awareness of the problem. The results behavior is different based on the bridge section inspected. The defects in the bridge superstructure are presented as positive thermal gradients. On the other hand, bridge infrastructure’s deficiencies are shown as negative thermal gradients. Although the technique presents several advantages for the inspection, the results must be analyzed in detail to avoid false detections, which may compromise the correct diagnosis of the bridge structures.

Mycotoxin source and its exposure causing mycotoxicoses.

Mycotoxins are toxic compounds produced by fungi such as Aspergillus, Penicillium, Rhizopus, Fusarium spp., and mushrooms. They are present in the mycelium or in the spores of the fungus. They cause human health problems once ingested. This is common in countries with high ambient temperature and relative humidity such as in the tropical regions. The consumption of moldy food and feeds are injurious to people and animals. The linked acute and chronic diseases target organs in humans and animals. The clinical symptoms depend on the intrinsic toxic features of the mycotoxin, the quantity, and length of exposure. The diseases caused by ingesting mycotoxins are reffred as mycotoxicoses. Therefore, it is of interest to document known data on the mycotoxin source and its exposure causing human hazards leading to mycotoxicoses.

Effect of PACAP on Heat Exposure.

Heat stroke is a life-threatening illness caused by exposure to high ambient temperatures and relative humidity. The incidence of heat stroke is expected to increase due to climate change. Although pituitary adenylate cyclase-activating polypeptide (PACAP) has been implicated in thermoregulation, the role of PACAP on heat stress remains unclear. PACAP knockout (KO) and wild-type ICR mice were subjected to heat exposure at an ambient temperature of 36 °C and relative humidity of 99% for 30-150 min. After heat exposure, the PACAP KO mice had a greater survival rate and maintained a lower body temperature than the wild-type mice. Moreover, the gene expression and immunoreaction of c-Fos in the ventromedially preoptic area of the hypothalamus, which is known to harbor temperature-sensitive neurons, were significantly lower in PACAP KO mice than those in wild-type mice. In addition, differences were observed in the brown adipose tissue, the primary site of heat production, between PACAP KO and wild-type mice. These results suggest that PACAP KO mice are resistant to heat exposure. The heat production mechanism differs between PACAP KO and wild-type mice.

Ambient relative humidity-dependent obstructive sleep apnea severity in cold season: A case-control study

BackgroundThe objective of this study was to examine associations of daily averages and daily variations in ambient relative humidity (RH), temperature, and PM2.5 on the obstructive sleep apnea (OSA) severity. MethodsA case-control study was conducted to retrospectively recruit 8628 subjects in a sleep center between January 2015 and December 2021, including 1307 control (apnea-hypopnea index (AHI) < 5 events/h), 3661 mild-to-moderate OSA (AHI of 5–30 events/h), and 3597 severe OSA subjects (AHI > 30 events/h). A logistic regression was used to examine the odds ratio (OR) of outcome variables (daily mean or difference in RH, temperature, and PM2.5 for 1, 7, and 30 days) with OSA severity (by the groups). Two-factor logistic regression models were conducted to examine the OR of RH with the daily mean or difference in temperature or PM2.5 with OSA severity. An exposure-response relationship analysis was conducted to examine the outcome variables with OSA severity in all, cold and warm seasons. ResultsWe observed associations of mean PM2.5 and RH with respective increases of 0.04–0.08 and 0.01–0.03 events/h for the AHI in OSA patients. An increase in the daily difference of 1 % RH increased the AHI by 0.02–0.03 events/h in OSA patients. A daily PM2.5 decrease of 1 μg/m3 reduced the AHI by 0.03 events/h, whereas a daily decrease in the RH of 1 % reduced the AHI by 0.03–0.04 events/h. The two-factor model confirmed the most robust associations of ambient RH with AHI in OSA patients. The exposure-response relationship in temperature and RH showed obviously seasonal patterns with OSA severity. ConclusionShort-term ambient variations in RH and PM2.5 were associated with changes in the AHI in OSA patients, especially RH in cold season. Reducing exposure to high ambient RH and PM2.5 levels may have protective effects on the AHI in OSA patients.

The Effects of Climate Change on Animal Nutrition, Production and Product Quality and Solution Suggestions

This article has been prepared to examine the effects of heat stress on livestock nutrition, yield and product quality, and to reveal strategies for adaptation and mitigation of climate change. Global climate change is primarily caused by greenhouse gas emissions, which result in warming of the atmosphere. Therefore, soil, air, water pollution and reductions in biodiversity may occur. At the same time, climate change can directly and indirectly affect livestock and animal nutrition. Heat stress results from inability to dissipate enough heat to maintain homeothermy of the animals. High ambient temperature, relative humidity and radiant energy compromise ability to dissipate heat of the animals. Ruminants, pigs and poultry are susceptible to heat stress due to their species-specific characteristics such as their metabolic rate and growth, high yield levels, rumen fermentation, sweating disorder and skin insulation. The indirect effects of climate change on livestock are changes in crop and forage production and quality, decrease in pasture/rangeland quality as a result of decrease in biodiversity and decrease in water availability. The direct effects are on the feed and water consumption, growth, milk, meat, egg, wool/hair and honey yield and product quality of the animals. These effects are primarily the result of a combination of temperature and increase in atmospheric carbon dioxide concentration, variation in precipitation, and relative humidity. Heat stress can cause significant losses in animal production, some of these may be immediate and some may be delayed. Animals under heat stress can decrease feed consumption to reduce metabolic heat. The decrease in feed consumption may cause a decrease in the growth rate of animals, decrease in milk, meat, egg, wool/hair yield and quality. The rations of animals can be manipulated to mitigate the negative effects of climate change.

Effect of Relative Humidity on the Population Dynamics of the Predator Amblyseius swirskii and Its Prey Carpoglyphus lactis in the Context of Slow-Release Sachets for Use in Biological Control in Greenhouses.

Amblyseius swirskii is a predatory mite that is widely used for biological control in greenhouses. One way this predator is released is in a formulation in slow-release sachets. These sachets are prepared with the predatory mite, the factitious prey mite Carpoglyphus lactis, and a food substrate for the latter. The objective of the present study was to study the effects of microclimatic conditions in this type of formulation on the population dynamics of mites inside the sachets and on the release of predatory mites. These experiments were conducted under laboratory conditions in two trials. The ambient relative humidity affected the water content of the food substrate of the prey mite inside the sachets, with an initial value of 21.49 ± 0.42%, which was reduced to values of 4.7 ± 0.25%, 10.87 ± 1.03% and 17.27 ± 0.82% after 21 days of trials when they were exposed to low, medium and high ambient relative humidity levels, respectively. Relative humidity significantly altered the dynamics of the populations of both species inside the sachets and the exits of the predator from the sachets to the external environment.

Effect of Temperature Gradient on Chloride Ion Diffusion in Nuclear Reactor Containment Building Concrete

Chloride diffusion through concrete is influenced by harsh environmental conditions such as high ambient temperature and relative humidity. This paper examined the influence of temperature gradient on chloride diffusion in concrete under high ambient temperature conditions. Chloride diffusion tests using cylindrical concrete samples were performed in constant temperature and temperature gradient conditions. In a temperature gradient condition, a much higher chloride concentration was measured than at constant temperatures, which could not be explained only by the mass diffusion driven by the concentration gradient. A new analytical model of chloride diffusion with the mass diffusion term including the temperature effect and the thermo-diffusion term including the temperature gradient effect was applied to the results, which showed that the thermo-diffusion contribution was significant. Using the analytical model with the mass diffusion (DCl) and thermo-diffusion (DT) coefficients, the service life of reactor containment buildings (RCBs) in nuclear power plants (NPPs) in the Middle Eastern and North African (MENA) region was estimated. The results showed that the service life of the RCBs could be reduced by the temperature gradient, indicating the possible application of the proposed analytical model.

Sprinkler flow rate affects physiological, behavioural and production responses of Holstein cows during heat stress

Holstein Friesian cows are known for their high milk yield. They are popular in the commercial dairy sector of Pakistan. Heat stress is a major challenge for these animals owing to the longer summer season with high ambient temperatures (35 - 40 °C) and relative humidity (30 - 50%) in the area (Butt et al., 2020). Mitigating the effects of heat stress requires substantial investments in energy and water. Spraying dairy cows with water in the holding pen or at the feed bunk is common practice as it lowers body temperature and respiration rate (Kendall et al., 2007; Chen et al., 2013; 2016), and improves feed intake and milk yield (Keister et al., 2002). Owing to the recent decrease in global groundwater, studies have focused on strategies to reduce the use of water to cool dairy cows (Chen et al., 2016). Sprinkler flow rates of 1.3 and 4.9 L/min had similar effects on physiological responses of cows to heat load but produced a 73% difference in water use (Chen et al., 2016). Similarly, Tresoldi et al. (2019) concluded that a sprinkler flow rate of 4.9 L/min had poor efficiency compared with 3.3 L/min, as the additional water did not result in increased biologically relevant cooling. These studies were conducted in Mediterranean climates with an average temperature humidity index in the range of 76 to 78. A recent study with Nili Ravi buffaloes revealed a sprinkler flow rate 1.25 L/min was more efficient than one of 2.0 L/min during subtropical summers (Bah et al., 2021). Because water is projected to be scarce in Pakistan by 2030 (Mustafa et al., 2013), holistic strategies for water conservation in the dairy sector are important nationally. The objective of this study was to evaluate the effects of various sprinkler flow rates on the performance of lactating Holstein Friesian cows in a typical corporate dairy farm setting during the subtropical summer. Performance of these cows was assumed to be similar, irrespective of the sprinkler flow rates.

Seasonal variations of mass absorption efficiency of elemental carbon in PM2.5 in urban Guangzhou of South China

This study investigates seasonal variations of mass absorption efficiency of elemental carbon (MAEEC) and possible influencing factors in urban Guangzhou of South China. Mass concentrations of elemental carbon (EC) and organic carbon (OC) in PM2.5 and aerosol absorption coefficient (bap) at multi-wavelengths were simultaneously measured in four seasons of 2018–2019 at hourly resolution by a semi-continuous carbon analyzer and an aethalometer. Seasonal average mass concentrations of EC were in the range of 1.36–1.70 µgC/m3 with a lower value in summer than in the other seasons, while those of OC were in the range of 4.70–6.49 µgC/m3 with the lowest value in summer and the highest in autumn. Vehicle exhaust from local traffic was identified to be the predominant source of carbonaceous aerosols. The average aerosol absorption Ångström exponents (AAE) were lower than 1.2 in four seasons, indicating EC and bap were closely related with vehicle exhaust. Seasonal MAEEC at 550 nm was 11.0, 8.5, 10.4 and 11.3 m2/g in spring, summer, autumn, and winter, respectively. High MAEEC was related with the high mass ratio of non-carbonaceous aerosols to EC and high ambient relative humidity.

Athlete Medical Services at the Marathon and Race Walking Events During Tokyo 2020 Olympics.

Epidemiological data from race walk and marathon events suggest that a high incidence rate of exertional heat illness is associated with high ambient temperature and relative humidity. The 2020 Summer Olympics in Tokyo was no exception, which led the organizing committee to relocate the race walk and marathon competitions to Sapporo, which was predicted to experience much milder heat. Nonetheless, during the Games, Sapporo recorded the highest daytime ambient temperature in the past 97 years, with consecutive days over 30°C from July 22nd to August 7th, 2021. Five events (men's and women's 20 km race walk, men's 50 km race walk, women's and men's marathon) were held in Sapporo from August 5th to August 8th, 2021. The percentage of athletes who did not finish (DNF) in each event was 8.8% in men's 20 km race walk, 20.3% in men's 50 km race walk, 8.6% in women's 20 km race walk, 17.1% in women's marathon and 28.3% in men's marathon. A total of fifty athletes were transferred to the athlete medical station: 28 athletes completed the race (i.e., collapsed after finish line), while 24 were DNF athletes transported from the course. Forty-eight (96%) of athletes who were admitted to the athlete medical station exhibited signs and symptoms of exertional heat illness. Two athletes diagnosed with exertional heat stroke and three athletes diagnosed with severe heat exhaustion (rectal body temperature >39.5°C with or without central nervous system disturbance) were cooled using whole-body cold water immersion at the heat deck located within the athlete medical station. All athletes who were cooled successfully recovered without any complications. These athletes required an average of 14 ± 9.4 min (range, 6–30 min) to cool their rectal temperature below 39°C. These results show the importance for event organizers to prepare strategies to keep athletes cool, such as an ample amount of ice and water to supply whole-body cold water immersion.

Characteristics of Turbulence and Aerosol Optical and Radiative Properties during Haze–Fog Episodes in Shenyang, Northeast China

The characteristics of turbulence in the planetary boundary layer (PBL) and the aerosol optical and radiative properties during haze and haze–fog mixed episodes on 22–27 January 2021, in Shenyang, a provincial city in Northeast China, were analyzed using meteorological and aerosol observations. During the haze episode, the hourly mean PM2.5 concentration reached a maximum of 337 µg m−3 and visibility decreased to 1.6 km. The PM2.5 concentration decreased gradually during the haze–fog mixed episode as a result of the scavenging effects of fog, but visibility mostly remained below 1 km owing to high ambient relative humidity (&gt;90%). During the haze–fog mixed episode, an increasing proportion of PM2.5 led to a higher ratio of the backward to the total scattering coefficient. As fog occurred, downward shortwave radiation arriving at the surface was significantly reduced, and upward longwave radiation increased and almost equaled the downward longwave radiation, which can be used as a good indicator for distinguishing haze and fog. Mechanical turbulence was weak during both episodes, and latent heat flux varied within a wider range during the haze–fog mixed episode. The PBL dynamic structure affected the vertical distribution of aerosols/fog droplets. Aerosol-rich layers appeared at altitudes below 0.5 km and above 0.6 km during the haze episode. The elevated aerosol layer was related to the aerosol transport from upstream polluted areas caused by strong upper-level turbulence, and it began to mix vertically after sunrise because of convective turbulence. Aerosols and fog droplets were mostly trapped in a shallower PBL with a height of 0.2–0.4 km during the haze–fog mixed episode because of weaker turbulence.

Photochemical Aging of Atmospheric Fine Particles as a Potential Source for Gas-Phase Hydrogen Peroxide.

Atmospheric hydrogen peroxide (H2O2), as an important oxidant, plays a key role in atmospheric sulfate formation, affecting the global radiation budget and causing acid rain deposition. The disproportionation reactions of hydroperoxyl radicals (HO2) in both gas and aqueous phases have long been considered as dominant sources for atmospheric H2O2. However, these known sources cannot explain the significant formation of H2O2 in polluted areas under the conditions of high NO levels and low ambient relative humidity (RH). Here, we show that under relatively dry conditions during daytime, atmospheric fine particles directly produce abundant gas-phase H2O2. The formation of H2O2 is verified to be by a reaction between the particle surface -OH group and HO2 radicals formed by photooxidation of chromophoric dissolved organic matters (CDOMs), which is slightly influenced by the presence of high NO levels but remarkably accelerated by water vapor and O2. In contrast to aqueous-phase chemistry, transition metal ions (TMIs) are found to significantly suppress H2O2 formation from the atmospheric fine particles. The H2O2 formed from relatively dry particles can be directly involved in in situ SO2 oxidation, leading to sulfate formation. As CDOMs are ubiquitous in atmospheric fine particles, their daytime photochemistry is expected to play important roles in formation of H2O2 and sulfate worldwide.

An active RH-controlled dry-ambient aerosol size spectrometer (DAASS) for the accurate measurement of ambient aerosol water content

A dry-ambient aerosol size spectrometer (DAASS) was previously developed to conduct measurements of aerosol water content at ambient relative humidity (RH) conditions. However, the RH difference of ambient RH and DAASS conditioning humidity (i.e., 10–20%, particularly when the DAASS operated at a high ambient RH) may introduce uncertainties in estimation of aerosol water content. In this study, we present a prototype of an RH-controlled DAASS. By employing an active RH controlling method, we resolve the discrepancy between the ambient RH and the DAASS conditioning RH, therefore extending the accurate measurement of aerosol water content to a wide RH range. The performance of this RH-controlled DAASS was characterized by both the laboratory evaluation and a 10-day field deployment. Results showed that the DAASS conditioning RH agreed well with the ambient RH (R2 of 0.993 when ambient RH up to 90%), with an average RH offset of less than 1.5%. The fraction of aerosol-bound water in the total ambient aerosol volume was ~10% under RHs below 50% and increased to ~50% when the ambient RH reached above 85%.

Deep Reinforcement Learning for Tropical Air Free-cooled Data Center Control

Air free-cooled data centers (DCs) have not existed in the tropical zone due to the unique challenges of year-round high ambient temperature and relative humidity (RH). The increasing availability of servers that can tolerate higher temperatures and RH due to the regulatory bodies’ prompts to raise DC temperature setpoints sheds light upon the feasibility of air free-cooled DCs in the tropics. However, due to the complex psychrometric dynamics, operating the air free-cooled DC in the tropics generally requires adaptive control of supply air condition to maintain the computing performance and reliability of the servers. This article studies the problem of controlling the supply air temperature and RH in a free-cooled tropical DC below certain thresholds. To achieve the goal, we formulate the control problem as Markov decision processes and apply deep reinforcement learning (DRL) to learn the control policy that minimizes the cooling energy while satisfying the requirements on the supply air temperature and RH. We also develop a constrained DRL solution for performance improvements. Extensive evaluation based on real data traces collected from an air free-cooled testbed and comparisons among the unconstrained and constrained DRL approaches as well as two other baseline approaches show the superior performance of our proposed solutions.

Relationship between Temperature-humidity Index and Milk Production of Dairy Cows in Tropical Climate

Background: Dairy cattle in many tropical, subtropical and semi-arid regions are subject to high ambient temperature and relative humidity for extended periods of time. This compromises the ability of the lactating cows to dissipate heat, resulting in heat stress and decreasing milk production. The objective of this study was to evaluate the effect of the temperature-humidity index (THI) on milk production in cows in the study area. Methods: Data on monthly milk production (2017 to 2019) was collected from the Department of Animal Production and Health, Batticaloa District, Sri Lanka and the monthly weather data (2017 to 2019) required for the study was collected from the Meteorological Observatory Station in Batticaloa, Sri Lanka. SPSS version 26 was used to analyze interaction between milk production and weather parameters. The monthly THI values were determined for each year.Result: Statistically significant negative relationship (p less than 0.05) was found between milk production and THI in 2017, 2018 and from 2017 to 2019 except 2019 due to the sudden death of cattle in Batticaloa district. Results of all three years indicated that milk production decreases as THI increases. It is concluded that the milk yield of cows is influenced significantly by heat stress during the dry season from April to August between 2017 and 2019, proper management strategies could be helpful to minimize heat stress to attain optimal performance of dairy cows.

Assessment of bio-contaminants during COVID-19 outbreak from the indoor environment of Hail city, Kingdom of Saudi Arabia.

Biocontaminants are minute particles derived from different biological materials. Indoor biocontaminants are associated with major public health problems. In Gulf countries, it is more precarious due to the harsh climatic conditions, including high ambient temperatures and relative humidity. In addition, due to COVID-19 pandemic, most of the time public is inside their home. Therefore, the aim of the study was to determine the load of biocontaminants in the indoor environment of Hail city. The results showed that most of the bacteria are gram-positive and higher in polymicrobial (87.1%) than monomicrobial (62.7%) association. There was no significant association with sample collection time and types of isolates. The most abundant microbes found in all samples were Staphylococcus aureus followed by Bacillus spp. Among Gram-negative bacterial isolates, E. coli was most common in tested indoor air samples. The study will be useful to find the biocontaminants associated with risk factors and their impact on human health in indoor environment, especially during the COVID-19 pandemic. These results indicate the need to implement health care awareness programs in the region to improve indoor air quality.