Abstract The study examines the development and application of microclimate standards for primary and secondary school classrooms, so as to ensure and promote the healthy growth of primary and secondary school students. The paper systematically reviews relevant domestic and international standards, analyzes the problems and shortcomings arising from their practical application and proposes effective countermeasures, in order to provide robust references aimed at optimizing the classroom environment in primary and secondary schools for student health, as well as offering practical support to advance the construction of a healthy China.

Objective: To understand the microclimate in primary and secondary school classrooms for the study period during the winter heating season, so as to provide a reference for the revision and improvement of relevant health standards. Methods: In December 2024, stratified random sampling was used to select 30 primary and secondary schools and 180 classrooms from the northern regions with centralized heating (Liaoning Province, Tianjin City) and the southern regions without centralized heating (Shanghai City, Anhui Province, and Jiangxi Province). Indoor temperature, relative humidity, wind speed, CO 2 and other indicators were measured on site. Variance analysis, t-test, Mann-Whitney U test and Kruskal-Wallis H test were used to analyze the differences in the microclimate of classrooms among regions and urban and rural differences. Results: The average temperature in the middle of the classrooms tested on site was (16.47±4.72)℃, and the variance analysis showed that the difference between the regions was statistically significant ( F=27.80, P <0.01). Among them, Tianjin had the highest average temperature of (20.43± 2.12 )℃, followed by Liaoning (19.03±2.23)℃, Shanghai (15.33±5.32)℃, Anhui (12.79±1.74)℃, and Jiangxi (11.69± 1.68 )℃. Horizontal temperature difference was 0.90 (0.50, 1.60)℃, the vertical temperature difference was 0.20 (0.10,0.60)℃, the average relative humidity was (44.39±16.16)%, the wind speed was 0.03(0.01,0.11)m/s, and the differences among different provinces and cities were statistically significant ( H/F =40.62, 82.69, 95.06, 55.28, all P <0.01). The average CO 2 volume concentration in urban areas of Tianjin, Liaoning, and Shanghai was 0.21(0.16,0.30)%, and there was no statistically significant difference ( H=4.65, P =0.10). There were grade differences in relative humidity ( F =3.71, 6.21) and CO 2 ( H =14.72, 12.92) in the north and the south (all P <0.05). In addition, the temperature, relative humidity, wind speed and CO 2 in the middle of the classroom were 42.8%, 67.8%, 100.0% and 22.2% respectively. Conclusions The temperature in the middle of the classroom in the non centralized heating area is lower than the standard, the relative humidity of classroom in the centralized heating area is lower than the standard，and the CO 2 in the classroom in winter is lower than the standard. It is recommended to install heating facilities in schools with low temperatures to increase the temperature and increase the frequency of ventilation in classrooms or adopt mechanical ventilation strategies to reduce CO 2 volume concentration.

Objective: To evaluate the classroom environmental management and CO 2 volume concentration in primary and secondary schools from Liaoning, Tianjin, and Shanghai, thereby providing a scientific basis for developing targeted strategies to improve classroom air quality. Methods: From December 16 to 26, 2024, by using stratified random cluster sampling method, the questionnaire survey was conducted in 72 primary and secondary schools (24 each of primary, junior high, and regular high schools) across Liaoning, Tianjin and Shanghai. Information on heating, ventilation and other classroom environmental management was collected. Additionally, 108 classrooms were selected for on site microclimate measurements, including temperature, humidity, wind speed and CO 2 volume concentration. Univariate analysis and multiple linear regression models were employed to explore related factors of classroom CO 2 volume concentration. Results: Among the three provinces/municipalities, 20.8% of schools regularly monitored the microclimate. The overall compliance rate for classroom CO 2 volume concentration was 17.6%. Multiple linear regression analysis showed that CO 2 volume concentration in regular and junior high school classrooms were higher than in primary school classrooms ( β=0.067, 0.046, 95%CI =0.036-0.099, 0.013-0.080); classrooms ventilated regularly in the morning and afternoon had higher CO 2 volume concentration than those ventilated during every break between classes ( β=0.043, 95%CI = 0.007- 0.080); both temperature ( β=0.010, 95%CI =0.004-0.016) and humidity ( β=0.003, 95%CI =0.002-0.004) were positively correlated with CO 2 volume concentration (all P <0.05). Conclusions Excessive CO 2 volume concentration in primary and secondary school classrooms is a prominent issue, and ventilation frequency is a key intervenable factor for controlling CO 2 levels. It is recommended to promote ventilation during every break between classes as a core management measure and to emphasize air quality supervision in regular high school classrooms.

Objective: To evaluate the current situation of thermal environment in primary and secondary school classrooms during winter, and to analyze students thermal comfort needs, so as to provide a basis for improving classroom thermal environment. Methods: From December 16 to 26, 2024, a stratified cluster random sampling method was used to select 90 classrooms from 15 primary and secondary schools in centralized/air conditioned heating areas(Liaoning Province, Tianjin City, Shanghai City) and naturally ventilated areas(Anhui Province and Jiangxi Province)for on site environmental measurement. A questionnaire survey was conducted among 743 students. The differences between groups using the χ 2 test were compared. Based on actual measurement data, a predicted mean vote prepared percentage of dissatisfied (PMV-PPD) model for centralized/air conditioned classrooms and an adaptive model for naturally ventilated classrooms were established, and the thermal neutral temperature and comfort interval were calculated. Results: The average outdoor temperature during on site measurement was 4.00(0.20，7.00)℃. In classrooms with centralized or air conditioned heating systems, the measured average temperature was (19.33±2.59)℃, with a thermal comfort range of 20.35-25.35 ℃ and a thermal neutral temperature of 22.85 ℃. And 13.92% of students reported feeling cold, while 80.80% felt comfortable. In classrooms with natural ventilation, the measured average temperature was (12.26±1.83)℃, with a thermal neutral temperature of 19.67 ℃ and a thermal comfort range of 16.17-23.17 ℃. About 48.33% of students reported feeling cold, and 49.81 % felt comfortable.The results of univariate analysis showed that there were statistically significant differences in shoe thickness, temperature sensation, relative humidity sensation and wind speed sensation between centralized/air conditioned heating areas ( χ 2= 7.01 , 31.47, 13.57, 13.80,all P <0.05). There were also statistically significant differences in school stage for primary and secondary school students, body mass index, classroom location for seat, temperature sensation, relative humidity sensation and wind speed sensation between naturally ventilated areas ( χ 2=42.13, 11.13, 11.04, 60.39, 29.27, 38.46,all P <0.05). Conclusions There are differences in thermal environment and students subjective thermal comfort in primary and secondary schools under different ventilation modes in winter. The temperature standards for heated classrooms should be revised, and differentiated environmental regulation strategies should be adopted based on different ventilation methods to improve students health and comfort levels.

Objective: To understand the serum vitamin D and vitamin K 1 levels of children in the Qingdao area, so as to provide scientific grounds for appropriate vitamin supplementation. Methods: A total of 4 469 children aged 0-14 years old, who attended the children s healthcare outpatient clinics of a tertiary hospital in Qingdao, were enrolled in the current study between January 2023 and July 2024. The levels of vitamin D and vitamin K 1 were measured by liquid chromatography tandem mass spectrometry. The inter group differences were analyzed using Chi square test, Wilcoxon rank sum test, and Kruskal-Wallis H test. The correlation analysis of vitamin D and vitamin K 1 levels with age was performed using the Spearman correlation. Results: The serum vitamin D level among children was 28.72(22.67, 36.26)ng/mL. The vitamin D deficiency and insufficiency rates were 2.10% and 14.59 %, respectively. The serum 25-(OH)D 2 level was 0.29(0.14, 0.53)ng/mL, the serum 25-(OH)D 3 level was 27.99( 21.78 , 35.57)ng/mL and the serum vitamin K 1 level was 0.54(0.29, 1.04)ng/mL. The vitamin K 1 deficiency rate was 13.76%. Among different age stages, the serum vitamin D level was highest in infancy [37.45(30.39, 43.87)ng/mL] and lowest in school age children [22.39(18.00, 26.97)ng/mL]; the level of vitamin K 1 was highest in preschool children [0.79(0.41, 1.51) ng/mL] and lowest in school age children[0.45 (0.26, 0.76) ng/mL]; the serum vitamin D deficiency and insufficiency rates were highest in school age children (5.03% and 30.81%); the vitamin K 1 deficiency rate was highest in infancy (21.53%) ( H/χ 2=1 698.31, 253.70 , 137.85 , 583.79, 89.30, all P <0.05). Among different seasons, the serum vitamin D and vitamin K 1 levels were lowest in the winter [26.74(18.37, 35.86) and 0.50 (0.27, 0.94)ng/mL; H =50.71, 7.86]; the vitamin D deficiency and insufficiency rates were highest in the winter (5.41% and 24.80%; χ 2=59.93, 83.35) (all P <0.05). The serum vitamin D level had a moderate negative correlation with age ( r =-0.62), and there was a low positive correlation between the serum vitamin D and vitamin K 1 levels in infancy and early childhood ( r =0.21, 0.26) (all P <0.05). Conclusions The serum vitamin D and vitamin K 1 levels are lowest in school age children and in the winter, and the serum vitamin K 1 deficiency rate is highest in infancy. There is a need to focus on critical periods of infancy and school age, and strengthen interventions during the high risk winter season. The nutritional status of vitamin D and vitamin K 1 in children should be enhanced.

: To analyze the prevalence of anemia and iron deficiency among primary and secondary school students in Rural Nutrition Improvement Program areas of Guizhou Province in 2023, and to explore the related factors, so as to provide evidence for Rural Nutrition Improvement Program optimization. Methods: In September 2023, a stratified random cluster sampling strategy was used to select 40 rural compulsory education schools with rural nutrition improvement program in five counties of Guizhou Province. School level questionnaire was employed to collect information of basic characteristics and school meal implementation. A total of 7 826 primary and secondary school students aged 6-16 underwent anthropometry and hemoglobin (Hb) determination; serum ferritin (SF) was additionally measured in a random subsample of 1 795 pupils. Students in Grade 3 and above also completed a questionnaire covering demographic characteristics, dietary behaviours and nutrition knowledge. Group comparisons were conducted by Chi square test or Fisher s exact test, and multivariable Logistic regression models were constructed to identify factors associated with anemia and iron deficiency. Results: The overall Hb level was (133.21±12.95)g/L, with an anemia prevalence of 7.17%. The overall SF level was (69.58±59.01)μg/L, with an iron deficiency prevalence of 2.73%. Multivariable analysis showed that stunting ( OR =1.88), school menus without nutrient calculation ( OR =1.61) and absence of menu planning software in the current semester ( OR =2.34) independently increased anemia risk, whereas obesity reduced it ( OR =0.54) (all P <0.05). Girls ( OR =4.16) and Grades 7-9 ( OR =5.93) increased iron deficiency risk (both P <0.05). Compared with rarely eating fresh vegetables, students with consuming <3 kinds per day ( OR =0.08) or exactly 3 kinds per day ( OR =0.06) had lower iron deficiency risks (both P <0.05). Conclusions Anemia and iron deficiency are prevalent among primary and secondary school students in Guizhou. Targeted intervention measures should be implemented for key populations to enhance the effectiveness of nutrition improvement program.

Objective: To evaluate the implementation process of a school-family collaborative "online+offline" tobacco control intervention program in junior high school in Beijing and to explore the execution status, influencing factors and sustainability potential of the intervention, so as to provide evidence for optimizing youth tobacco control strategies. Methods: In November 2024, using the random number table method, four first year junior high school classes were selected from three schools each in Fengtai District, Tongzhou District, and Fangshan District of Beijing. One class served as the control group, while the other three classes were designated as intervention groups (one each for online intervention, offline intervention, and combined online offline intervention). The control group received only conventional education.The online intervention group was engaged in WeChat push interventions, including watching micro videos, viewing promotional materials, participating in online quizzes and mini games; the offline intervention group attended knowledge lectures, played peer games, and participated in offline knowledge competitions; the combined online offline intervention group integrated all the aforementioned online and offline intervention measures. The intervention period was from November 2024 to June 2025, spanning a total of 7 months. Based on the Practical, Robust Implementation and Sustainability Model(PRISM) framework, a qualitative research design was employed to conduct semi structured interviews with 48 participants (12 in each of the intervention groups and 12 organizational staff members) from the Centers for Disease Control and Prevention (CDC) in 3 districts and 3 sampled schools. The interview outlines were designed according to the intervention plan. Data was managed using Nvivo 12.0 software and analyzed following Colaizzi s seven step phenomenological analysis method. Theoretical saturation was assessed using a reserved subset of transcripts. Results: Four core themes were identified in the tobacco control intervention process. Overall fidelity of intervention implementation was largely consistent with the original plan, and students showed strong willingness and positive evaluations toward interactive formats such as knowledge contests and peer games, though occasional breakdowns in school-family communication and blurred boundaries between online and offline components were observed; the participants showed a polarized response in terms of satisfaction and participation, most students and parents recognized the significance of the activity, and some parents observed a reduction in smoking behavior; the implementation of internal tobacco control policies in the school was strict, and the atmosphere was favorable, but there was still room for improvement, such as the scarcity of community tobacco control activities and the difficulty in implementing smoke free units; implementation and sustainability infrastructure were preliminarily established, such as through homeroom teacher supervision and training student assistants to assisted in activities, while the sustainability support system required further refinement. Conclusion The school-family collaborative "online+offline" tobacco control intervention has demonstrated significant positive effects, but further optimization of activity design, enhancement of community reward mechanisms, and standardized training are required to improve the efficacy and sustainability of the intervention.

Objective: To analyze the developmental trajectories of clustered health risk behaviors and their association with self-esteem and lonelinesss among junior high school students, so as to provide a reference for formulating comprehensive prevention and control measures of health risk behaviors among adolescents. Methods: In October 2023, 1 165 first year junior high school students from two schools of Jishou City in Hunan Province were selected by convenient sampling method for three follow up surveys (T1:October 2023; T2:April 2024; T3:October 2024). The Adolescent Health Risk Behavior Questionnaire, Rosenberg Self esteem Scale and Loneliness Scale were used to assess health risk behaviors, self esteem and loneliness, respectively. Latent growth curve modeling and latent growth mixture modeling were applied to analyze the developmental trajectories of clustered health risk behaviors among junior high school students. Logistic regression was used to analyze the association of the developmental trajectories of clustered health risk behaviors with self esteem and loneliness among junior high school students. Results: The overall developmental trajectories among junior high school students showed a declining trend (intercept=0.15, slope=-1.65, both P <0.05), with three heterogeneous categories:low risk improvement group ( n =862, 74.0%), moderate risk stable group ( n =260, 22.3%), and high risk deterioration group ( n =43, 3.7%). After adjusting the status of the left behind individuals，using the low risk improvement group as the reference category in multinomial Logistic regression analysis, results indicated that higher loneliness scores among junior high school students increased the risks of belonging to the moderate risk stable group ( OR=1.02, 95%CI =1.00- 1.04 ) and the high risk deterioration group ( OR=1.04, 95%CI =1.00-1.08), while higher self esteem scores reduced the risks of belonging to the moderate risk stable group ( OR=0.93, 95%CI =0.91-0.96) and the high risk deterioration group ( OR=0.88, 95%CI =0.83-0.94) (all P <0.05). Conclusions The overall trend of clustered health risk behaviors among junior high school students gradually improves, and the self esteem and loneliness are significant correlative factors. Targeted intervention measures should be developed for the junior high school students, with a focus on enhancing their self esteem and alleviating loneliness.

Objective: To identify the effective needs of college students for dietary nutrition health education content, so as to provide a scientific basis for optimizing the health education strategies in colleges. Methods: The literature analysis method, focus group interviews and Delphi expert consultation method were used to construct a survey questionnaire on dietary nutrition health education for college students. From January to March 2024, a total of 597 college students from six colleges in Shandong Province were selected through convenience sampling to complete the questionnaire independently by scanning the two dimensional code on questionnaire star. The Kano model was used to define the content demands of college students for dietary nutrition education, and the differences in demands were analyzed by calculating satisfied influence (SI) and dissatisfied influence (DSI). Results: The compiled questionnaire was divided into 7 dimensions and 25 items. The overall demand level analysis of college students included 3 essential attribute demands, namely, the recommended intake and various forms of dairy products (34.17%), the role of whole grains in health with their scientific intake forms and recommended amounts (31.99%), and the intake of beans (30.15%); 7 expected attribute demands included the introduction of recommended intensity of different activities (35.01%), how to achieve a healthy weight and the balance between diet and exercise (41.54%), the energy consumed by different exercises in a unit of time ( 38.36 %), the selection of healthy snacks (36.68%), the types of infectious diseases of the digestive system and how to prevent and control them (25.96%), the causes and judgments with manifestations of nutrition related diseases among college students ( 28.14 %), and the hotspots of attention on nutrition related diseases among college students (24.46%); 4 attractive attribute demands contained the introduction of the recommended activity levels for different periods such as daily and weekly (28.81%), the introduction of the importance of activities and the harm of prolonged sitting and ways to avoid it (28.64%), the nutritional value of animal foods and eating suggestions (23.45%), and the scientific intake suggestions for various processed animal foods (22.11%); the remaining were 11 attribute demands with no differences. In the quadrant diagram analysis, the demand items located in the maintenance zone, competitive advantage zone, improvement zone, and minor improvement zone were 5, 5, 8, and 7, respectively. Conclusions College students have different demands in dietary nutrition health education, and whether these demands are met affects their satisfaction in different ways. Among them, education on the intake of dairy products, whole grains, and beans has the greatest impact on satisfaction.

Objective: To explore the effects of the school based integrated horticulture curriculum intervention on 24 hour activity behaviors among third grade primary school students, so as to provide reference for promoting children s health. Methods: In September 2023, a convenience sampling method was used to select 90 third grade primary school students from a primary school in Changsha. Participants were randomly assigned to an intervention group ( n =45) and a control group ( n =45) using a random number table. From February to May 2024, the intervention group received a 12 week integrated curriculum intervention, consisting of two 60 minute sessions per week and covering horticultural practice, home-school collaborative tasks and nutrition knowledge education. The control group continued with routine labor education courses. The triaxial accelerometer and multi sensor sleep monitoring device were used to objectively measure light intensity physical activity (LPA), moderate to vigorous physical activity (MVPA), screen based sedentary behavior (SSB) and sleep (SLP), durations in both groups. Data were analyzed using generalized estimating equations (GEE) and Mann-Whitney U tests. Results: The time, group and interaction effects of MVPA time and SLP time before and after intervention in two groups of primary school students were not statistically significant (Wald χ 2=1.54, 2.97, 0.85 ; 0.75, 1.05, 0.48), and the group effect of LPA time (Wald χ 2=1.24) and the time and group effects (Wald χ 2=3.02, 1.18 ) were not statistically significant (all P >0.05). There were statistically significant time and interaction effects for LPA time, as well as interaction effect for SSB time in two groups of primary school students before and after intervention (Wald χ 2=4.78, 3.95, 12.60, all P <0.05). After intervention, LPA time of intervention group [152.23(59.15, 245.80)min] was higher than that of control group [120.70(29.90, 201.20)min], and SSB time of intervention group [55.50(30.00, 125.50)min] was lower than that of control group [220.00(60.00, 285.00)min], with statistically significant differences ( Z =-2.46, -4.48, both P <0.05). Conclusion The school horticulture curriculum effectively enhances daily LPA and reduces SSB among third grade primary school students.