![Time to unconsciousness in humans exposed to CO 2 in high and low O 2 environments [3,5,7-15].](https://www.researchgate.net/profile/Susan-Rice-3/publication/228863103/figure/fig1/AS:669483848986626@1536628796084/Time-to-unconsciousness-in-humans-exposed-to-CO-2-in-high-and-low-O-2-environments_Q320.jpg)
![The ambient CO 2 and O 2 concentrations measured or estimated where death occurred [7,25,26]. Times shown are the time at which the victim was removed from the CO 2 environment, and not the actual time to death.](https://www.researchgate.net/profile/Susan-Rice-3/publication/228863103/figure/fig2/AS:669483848962050@1536628796095/The-ambient-CO-2-and-O-2-concentrations-measured-or-estimated-where-death-occurred_Q320.jpg)
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Human Health Risk Assessment of CO2: Survivors of Acute High-Level Exposure and Populations Sensitive to Prolonged Low-Level Exposure
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... Severe health effects of CO 2 only occur under extremely high concentrations. In 1986, at Lake Nyos in Cameroon multiple people died due to an exposure to estimated CO 2 concentrations of 8-10% (i.e., 80 000 -100 000 ppm) (Rice, 2014); this concentration was caused by a sudden outgassing of CO 2 stored in the lake. Rice (2014) reports other adverse health effects, such as decreased lung functioning, from 8500 ppm. ...
... In 1986, at Lake Nyos in Cameroon multiple people died due to an exposure to estimated CO 2 concentrations of 8-10% (i.e., 80 000 -100 000 ppm) (Rice, 2014); this concentration was caused by a sudden outgassing of CO 2 stored in the lake. Rice (2014) reports other adverse health effects, such as decreased lung functioning, from 8500 ppm. Such high levels, however, generally not occur when the primary source is human respiration. ...
Students in a country like Ethiopia face a double air pollution challenge: they are frequently exposed (both outdoors and indoors) to sources of incomplete combustion and therefore to unhealthy concentrations of particulate matter (PM2.5) and carbon monoxide (CO), while they also face increased carbon dioxide (CO2) concentrations in crowded dormitories and classrooms. Research on air pollution in the environment of Ethiopian students is scarce. This lack of research can be fixed by involving students in science through a student science project, essentially a subset of citizen science. Students of Arba Minch University, Ethiopia, conducted measurements of PM2.5, CO, and CO2 under self-selected circumstances. Their measurements are compared to guideline values related to health effects to identify priority areas for future research. For PM2.5, students’ measurements show likely exceedances of guideline values for an inside coffee ceremony, close to open waste burning, at a bus station and close to a diesel generator. For CO, exceedances are revealed in kitchens and the visitor’s area of restaurants using biomass fuel, close to outdoor charcoal cooking and close to waste burning. For CO2, exceedances are found within student dormitories. These areas can be considered priority areas for further research. Students can conduct additional measurements to distinguish other relevant scenarios. Insight into exposure can be improved if, besides different concentrations under different circumstances, also time durations of these different circumstances are studied. The findings reveal that students themselves can be a partial solution to research and resource gaps in their context.
... Dato que ha provocado que se realicen esfuerzos conjuntos entre los países más desarrollados y se propongan decisiones para resolver este problema. Sin embargo, para tomar decisiones eficaces fue necesario primero tomar acciones de monitoreo de gases, lo que originó que la primera década del siglo XXI fuera denominada la "década del sensor" (Wilson, 2004;Rice, 2004;Bogue, 2008). ...
... Significant degrees of carbon dioxide can prompt health complaints, e.g., headaches. Carbon dioxide levels may demonstrate significant degrees of other harmful air toxins, e.g., volatile organic compounds, which add to indoor air contamination (Loladze et al., 2019;Mallongi et al., 2020;Rice, 2014). ...
... Dato que ha provocado que se realicen esfuerzos conjuntos entre los países más desarrollados y se propongan decisiones para resolver este problema. Sin embargo, para tomar decisiones eficaces fue necesario primero tomar acciones de monitoreo de gases, lo que originó que la primera década del siglo XXI fuera denominada la "década del sensor" (Wilson, 2004;Rice, 2004;Bogue, 2008). ...
... One-hour exposure of~25 ppb NO 2 is associated with 1.3% increase in the daily number of deaths [26]. The effects of high-level CO 2 exposure are physiologic, toxic, and potentially lethal [27]. CO 2 levels should not exceed 1000 ppm [28]. ...
The concentration of air pollutants in underground parking garages has been found to be higher compared to ambient air. Vehicle emissions from cold starts are the main sources of air pollution in underground parking garages. Eight days of measurements, using low-cost air sensors, were conducted at one underground parking garage at the University of Minnesota, Minneapolis. The CO, NO, NO2, and PM2.5 daily average concentrations in the parking garage were measured to be higher, by up to more than an order of magnitude, compared to the ambient concentration. There is positive correlation between exit traffic flow and the air concentrations in the parking garage for lung deposited surface area (LDSA), CO2, NO, and CO. Fuel specific emission factors were calculated for CO, NO, and NOx. Ranging from 25 to 28 g/kgfuel for CO, from 1.3 to 1.7 g/kgfuel for NO, and from 2.1 to 2.7 g/kgfuel for NOx. Regulated emissions were also calculated for CO and NOx with values of 2.4 to 2.9 and 0.19 to 0.25 g/mile, respectively. These emissions are about 50% higher than the 2017 U.S. emission standards for CO and nearly an order magnitude higher for NOx.
... Dato que ha provocado que se realicen esfuerzos conjuntos entre los países más desarrollados y se propongan decisiones para resolver este problema. Sin embargo, para tomar decisiones eficaces fue necesario primero tomar acciones de monitoreo de gases, lo que originó que la primera década del siglo XXI fuera denominada la "década del sensor" (Wilson, 2004;Rice, 2004;Bogue, 2008). ...
Un sensor es un objeto que tiene la capacidad de percibir un estímulo físico (por ejemplo, luz, calor, sonido, magnetismo, electricidad, movimiento, etc.) y responder mediante una señal. Variando el tipo de estímulo y la señal de respuesta del sensor la ciencia ha diseñado sensores diversos dependiendo de su área de aplicación. Este texto se centra en sensores que son capaces de detectar gases y emitir una señal eléctrica en respuesta. Existe un sensor de gas que se encuentra en el cuerpo humano y es el sistema olfativo, que por medio de la nariz detecta “olores” que propiamente son gases y envía señales eléctricas al cerebro. Es así que la nariz humana ha sido utilizada en diversas industrias para evaluar el olor de productos que van desde perfumes hasta alimentos, sin embargo, es un proceso costoso, de alto riesgo y los resultados suelen tener problemas debido a que cada persona tiende dar resultados diferentes para un mismo estímulo (Craven, Gardner, & Bartlett, 1996). Además, es importante considerar el aspecto ético que se ve comprometido cuando no se consideran los riesgos al utilizar a una persona para detectar gases en la industria. En este sentido los investigadores a nivel mundial han enfocando sus esfuerzos en desarrollar tecnologías que permitan el uso de sensores sin riesgo para el humano. Un aspecto a destacar es el crecimiento económico a través del trabajo inclusivo, generando empleos decentes, garantizando una vida sana en el trabajo y el desarrollo de los individuos. La figura 1 muestra una comparación entre la detección de gases de los humanos y cómo lo hacen los dispositivos. En la figura 1a, se observa cómo se perciben los gases no inodoros mediante el sistema olfatorio que detecta un gas introducido en la cavidad nasal y la interacción con las neuronas olfativas. Este proceso produce información que es envíada en forma de señales eléctricas desde el bulbo olfativo hasta el cerebro, que recibe y procesa esa información. Por otro lado, se observa en la figura 1b un esquema simplificado de un sensor de gas basado en óxidos metálicos semiconductores que detecta ciertos gases mediante la capa de detección registrando un cambio en la conductividad del material siendo confirmado por el óhmetro.
En este trabajo se presentan las características y propiedades de los sensores de gas, así como la importancia de éstos en el desarrollo de la ciencia y tecnología en diversas áreas del conocimiento. El capítulo de libro está estructurado en tres secciones considerando los objetivos de desarrollo sostenible (ODS) 3 (salud y bienestar), 7 (energía asequible y no contaminante) y 11 (ciudades y comunidades sostenibles). La sección 1 se titula “Uso de sensores en el área de la salud” donde se aborda principalmente la contribución de esta tecnología en la mitigación de las consecuencias negativas de la pandemia covid-19 por la que atravesamos. En la sección 2 “Energía asequible y no contaminante en la elaboración de sensores” se abordan los métodos de química verde para la obtención de sensores de gas y la sección 3 “Implementación de sensores en ciudades y comunidades sostenibles” se presenta el panorama actual y las estrategías a seguir en función de la agenda 2030 de las naciones unidas.
Integrating cities with the surrounding environment by incorporating green spaces in creative ways would help counter climate change. We propose a rooftop farm system called BIG GRO where air enriched with carbon dioxide (CO 2 ) produced through respiration from indoor spaces is applied through existing ventilation systems to produce a fertilization effect and increased plant growth. CO 2 measurements were taken inside 20 classrooms and at two exhaust vents on a rooftop at Boston University in Boston, MA. Exhausted air was directed toward spinach and corn and plant biomass and leaf number were analyzed. High concentrations of CO 2 persisted inside classrooms and at rooftop exhaust vents in correlation with expected human occupancy. CO 2 levels averaged 1,070 and 830 parts per million (ppm), reaching a maximum of 4,470 and 1,300 ppm CO 2 indoors and at exhaust vents, respectively. The biomass of spinach grown next to exhaust air increased fourfold compared to plants grown next to a control fan applying atmospheric air. High wind speed from fans decreased growth by approximately twofold. The biomass of corn, a C4 plant, experienced a two to threefold increase, indicating that alternative environmental factors, such as temperature, likely contribute to growth enhancement. Enhancing growth in rooftop farms using indoor air would help increase yield and help crops survive harsh conditions, which would make their installation in cities more feasible.
From the experience of CO2 storage in the past, the leakage part of CO2 may be the wellbore, fractures, faults, and cap rocks in the formation. Once CO2 leaks from the wellbore, it will pose a serious threat to the life safety of workers near the well pad in a short time. Therefore, from the perspective of single well leakage in the process of CO2 storage, this paper studies the risk of single well CO2 injection leakage in Changqing Oilfield, Ordos Basin, simulates CO2 leakage from the wellbore, and simulates it with the diffusion model after toxic gas leakage, so as to obtain the CO2 concentration at different distances from the leakage point. The range of affected area after CO2 leakage is determined by the critical value of CO2 leakage diffusion concentration. According to the calculation in this paper, the area near the leakage source is divided into (taking summer as an example: the wind speed is about 3.3 m/s): fatal area (2.2 m), serious injury area (4.3 m), inhalation reaction region (19.5 m) and safety area (> 50 m). The leakage risk of CO2 injection buried wellbore in low-permeability reservoir in Ordos Basin is evaluated.
Chronic respiratory acidosis induced by an elevated carbon dioxide (CO2) environment should provoke hypercalciuria with related total body and subsequent bone calcium losses. We examined this hypothesis in four healthy male volunteers, who were exposed during a 25-d period to an 0.7% CO2 environment within a deep diving isolation chamber. Three months later the same subjects were reexamined during a second campaign being exposed to a 1.2% CO2 atmosphere.
The subjects received a constant calcium intake (1.4 g.d-1) and vitamin D supplement (1000 IU.d-1) during both campaigns. Calcium balance (oral calcium intake minus urinary and fecal calcium output) was evaluated. Serum calcium concentrations and biomarkers of bone metabolism were measured, in order to evaluate bone turnover. Additionally, the response to an acute oral calcium load was examined as a sensitive measure of changes in calcium metabolism.
Both, urinary calcium excretion (from 245 +/- 38 to 199 +/- 31 mg.d-1; mean +/- SE, 0.7% and 1.2%, respectively) and fecal calcium losses (from 1229 +/- 128 to 996 +/- 62 mg.d-1) were significantly reduced in the higher (1.2%) CO2 atmosphere. Although more calcium was retained in the body during the 1.2% than during the 0.7% CO2 campaign, serum calcium concentrations and biomarkers of bone formation were significantly lower in the higher CO2 campaign. Furthermore, bone resorption was slightly increased in the 1.2% experiment.
Elevated CO2 atmosphere may dose-dependently preserve body calcium without a parallel improvement of bone substance.
Two persons, an employee of the Department of Water Resources and a police officer, were asphyxiated in an underground water valve vault. The two deaths were caused by a gross deficiency of oxygen associated with an elevated level of carbon dioxide. This lethal atmosphere produced rapid loss of consciousness and death within a matter of minutes. The atmosphere was produced by fungus like organisms and low forms of plant life present on the vault walls and in the sediment on the floor. The small amount of methane gas present was felt to have played no part in the deaths and to have been produced by the same biological processes that resulted in the lethal atmosphere.
Acid-base balance regulation and changes in electrolyte metabolism have been studied in 20 subjects exposed to 1.5% CO 2 over a period of 42 days with control periods preceding and subsequent to exposure. During exposure to CO 2 a slight uncompensated respiratory acidosis was present during the first 23 days followed by a compensated respiratory acidosis. Deacclimatization was incomplete, even after 4 weeks of recovery on air. Arterial CO 2 tension increased 5 mm Hg during exposure and remained at this elevated level during the first 9 days of recovery on air. In chronic respiratory acidosis the concentration of chloride in the red cells and in plasma remains practically normal, indicating that the chloride shift does not operate. Cation exchange was observed under these conditions. Sodium increased while potassium showed an approximately equivalent decrease. Sodium and potassium balance studies indicated that only sodium exhibits a pattern paralleling the two phases of acid-base balance regulation, retention being followed by increased excretion. Body weight was maintained throughout the experiment in spite of a 24–30% reduction in food intake.
mild respiratory acidosis and compensation; 1.5% CO 2 exposure and recovery; arterial pCO 2 , chloride shift, and cation exchange; sodium and potassium excretion; sodium potassium and nitrogen balance; acid-base regulation in chronic hypercapnia; time course in acid-base regulations during chronic exposure to low concentration of CO 2 ; acclimatization and deacclimatization to low concentration of CO 2
Submitted on July 22, 1963
The present authors investigated the effect of CO2 on human mental performance, critical fusion frequency of flicker, and hearing. In view of the results obtained, we conclude as follows:1. The critical concentration of CO2 to maintain the above stated functions almost unaltered for a long period is safely regarded as 4%. But 5% CO2 shows practically no appreciable effect upon them for 2-3 hours. Subjective complaints due to the CO2 inhalation also appear above 5%.2. This critical concentration coincides with that, in which steep rise of alveolar pCO2 and remarkable respiratory acidosis begin to occur, and functions under bulbar or hypothalamic control (respiration, heart rate, vasomotor or sweating response) start with acceleration. It seems allowable, therefore, to ascribe the narcotic action of CO2 to its effects exerted on nervous elements in general such as investigated by Lorente de No, and to be either narcotic for cortical centres or excitatory for subcortical ones, corresponding to their respective characteristics in formation of synaptic circuit.3. Above 6%, its narcotic effect on mental performance or sensory functions and subjective symptoms become distinct. Concerning the mode of its action, Clark's formulation seems applicable for the effect-concentration relationship and an expression of Harber's type for the concentration-time relation.4. It seems probable that not only the elevated pCO2 due to CO2 inhalation, but also magnitude of dpCO2/dt affects the cortical functions, even though only transiently.
Available medical evidence on the acute health impact of the gas release at Lake Nyos is summarised, including the results of a survey of medical records of 845 survivors treated at Wum and Nkambe hospitals. The main clinical features were compatible with exposure to an asphyxiant gas such as CO2 but confirmation of the identity of the gas or gases involved was not possible. Exposure to CO2 over such a large inhabited area and reversible coma lasting for hours after CO2 gassing do not appear to have been reported before. In some victims, blistering or ulceration of the skin was present which could not be readily explained by local injury from pressure, or burns from acid, or falling near fires. Further epidemiological studies on survivors are unlikely to be feasible, but the possibility of long-term anoxic brain damage among adults and children who had been rendered comatose by the gas should be considered, though overt evidence of major neurological or respiratory disability was not apparent in survivors in the weeks following the disaster. The inadequacy of the toxicological and forensic evidence obtained points to the need for the rapid mobilisation of medical scientists in future disasters of this kind.
Cerebral blood flow velocity (CBFv) was measured by insonating the middle cerebral arteries of four subjects using a 2 Mhz transcranial Doppler. Ambient CO2 was elevated to 0.7% for 23 d in the first study and to 1.2% for 23 d in the same subjects in the second study. By non-parametric testing CBFv was elevated significantly by +35% above pre-exposure levels during the first 1-3 d at both exposure levels, after which CBFv progressively readjusted to pre-exposure levels. Despite similar CBFv responses, headache was only reported during the initial phase of exposure to 1.2% CO2. Vascular reactivity to CO2 assessed by rebreathing showed a similar pattern with the CBFv increases early in the exposures being greater than those elicited later. An increase in metabolic rate of the visual cortex was evoked by having the subjects open and close their eyes during a visual stimulus. Evoked CBFv responses measured in the posterior cerebral artery were also elevated in the first 1-3 d of both studies returning to pre-exposure levels as hypercapnia continued. Cerebral vascular autoregulation assessed by raising head pressure during 10 degrees head-down tilt both during the low-level exposures and during rebreathing was unaltered. There were no changes in the retinal microcirculation during serial fundoscopy studies. The time-dependent changes in CO2 vascular reactivity might be due either to retention of bicarbonate in brain extracellular fluid or to progressive increases in ventilation, or both. Cerebral vascular autoregulation appears preserved during chronic exposure to these low levels of ambient CO2.