We first calculated the number of fatal indoor CO incidents and similar cases, and then estimated the number of deaths in Jinan from 2007 to 2021 overall and each year. Further, we described the spatial and temporal characteristics of CO toxicity. In terms of space, we compared the differences between urban and rural areas by drawing a map. In terms of time, we defined the time of CO poisoning as annual, monthly, and hourly. Finally, we analyzed the individual’s risk in relation to death and CO disease and made appropriate interventions. The steps and details are as follows:
Students
This study was approved by the Ethics Committees of the School of Public Health, Shandong University (identification was LL20220922) and informed consent was obtained from all participants and/or their legal guardians. This study was in accordance with the Declaration of Helsinki.
More about Jinan
Jinan is located at 36.40° N latitude and 110.00° E longitude and has an area of 8,177.21 kilometers.2It is divided into 10 districts including five urban districts of Lixia, Shizhong, Huaiyin, Tianqiao, Licheng and five rural districts of Changqing, Zhangqiu, Jiyang, Pingyin and Shanghai.15. It has a hot monsoon season with distinctly divided seasons and the winter season lasts about 150 days (from November to the following March).16. The minimum temperature in winter is usually below −10 °C and severe weather such as cold waves, snow sometimes occurred in January and December. According to Jinan Urban Central Heating Management Regulations17the urban area was dedicated to central heating services from March 15 to November 15 (121 days each year), while in rural and urban areas, coal heating is used more often due to limited space, which greatly increases the risk of CO poisoning. .
Data collection
Daily weather data from 2007 to 2021 were provided by the China Meteorological Data Sharing Service System network.18including daily temperature, maximum daily temperature and daily temperature.
The daily inactive CO toxicity profiles in Jinan from 2007 to 2021 were obtained from. China Public Health Emergency Information System19,20. A system based on 91 well-known hospitals and an integrated history of epidemics/incidents related to infectious diseases, food-borne diseases, water-borne diseases, occupational poisoning, environmental hazards (indoor and outdoor air pollution), and other unknown incidents better for public health. An inert CO poisoning incident occurred during an environmental emergency. We collected CO poisoning cases as date of onset (time of hospital visit), site of poisoning, cause of death, amount of CO, and severity of poisoning.
The causes of non-active CO poisoning in Jinan include indoor coal burning, food gas leakage, suicide, etc. (caused by other events). From 2007 to 2021, CO poisoning due to the burning of coal in the house is 81%, which was the main cause of CO poisoning. Therefore, the spatiotemporal characteristics and trends of indoor coal heating were analyzed in this study.
A qualitative epidemiological analysis
Using descriptive epidemiological methods to analyze the temporal, spatial and population levels of CO poisoning from indoor coal burning. The exposure rate, incidence rate (cases) and mortality rate were measured using the following method:
$$\mathrmExposure\, Rate = \frac\mathrmNumber \,of \,CO \,Exposed \,Individual\mathrm Annual \,Population \,\times \,\mathrm Time \,(\mathrmyears)\,\times\, \mathrm100,000$$
(units: per 100,000 person-years).
$$\mathrmIncidence \,Density = \frac\mathrmNumber \,of \,CO \,Poisoning\, Cases\mathrmAnnual\, Population\, \times \,\mathrm Time \,(\mathrmyears)\,\times \,\mathrm100,000$$
(units: per 100,000 person-years).
$$\mathrmMortality\, Rate = \frac\mathrmNumber \,of \,CO \,Poisoning \,Deaths\mathrmAnnual \,Population \,\times\, \mathrm Time\, (\mathrmyears)\,\times \,\mathrm100,000$$
(units: per 100,000 person-years).
Statistical analysis
We set up an Excel database and used descriptive epidemiological methods to analyze the data. Spatial analysis was performed with RStudio version 3.5.1. Statistical analysis was performed with SPSS 21.0 (SPSS Inc., Chicago, IL, USA). The Chi-Square test was used to compare rates, the statistical significance level was set at 0.05.
Ethical consent and consent to participate
The study was approved by the Ethics Committees of the School of Public Health, Shandong University (identification was LL20220922) and informed consent was obtained from all participants and/or their legal guardians. This study was in accordance with the Declaration of Helsinki.
