Under the principle that a suitable temperature and air quality are key to guarantee optimal conditions of learning and growth to students, this study has evaluated the comfort of the classrooms from the data extracted after analyzing the temperatures, the interior of each building, as well as the relative humidity of the classroom environment. In addition, to measure the quality of the indoor air, six chemical contaminants of Carbon Dioxide (CO2), Carbon Monoxide (CO), Nitrogen Dioxide (NO2), Formaldehyde (HCHO), Volatile Organic Compound (VOC) and Particulate Matter (PM) in the classroom were measured. The results indicate that the physical parameters of each building were in good condition. Meanwhile, on the chemical contaminants, the measurement shows that the concentration of CO2, PM and VOC for most buildings exceeds the acceptable exposure limits. In the end, the recommendations for a good quality of the indoor environment in the classroom have been suggested through an emphasis on good design, construction and renovation of buildings as well as continuous maintenance practices.

Additive manufacturing (AM) stands out as one of the promising technologies that have huge potential towards manufacturing industry. The study on additive manufacturing impact on the environment and occupational exposure are attracting growing attention recently. However, most of the researcher focus on desktop and fused deposition modelling type and less attention given to the industrial type of AM. Usually, during the selective laser sintering process, recycle powder will be used again to reduce cost and waste. This article compares the PM 2.5, carbon dioxide (CO2) and total volatile organic compound (TVOC) concentration between virgin and recycles powder using polyamide-nylon (PA12) towards indoor concentration. Four phases of sampling involve during air sampling accordingly to the Industry Code of Practice on Indoor Air Quality 2010 by DOSH Malaysia. It was found that PM 2.5 and CO2concentration are mainly generated during the pre-printing process. The recycle powder tended to appear higher compared to virgin powder in terms of PM 2.5, and CO2. The peak value of PM 2.5 is 1452 µg/m3 and CO2 is 1218 ppm are obtained during the pre-printing process during 8 hours of sampling. TVOC concentration from recycling powder is slightly higher during the post- printing phase where confirm the influence of the powder cake and PA12 temperature from the printing process. In summary, this work proves that elective laser sintering (SLS) machine operators are exposed to a significant amount of exposure during the SLS printing process. Mitigation strategies and personal protective equipment are suggested to reduce occupational exposure.

Indoor Air Quality (IAQ) problems are very important and necessary to consider in hospital and health care facilities such as in AMBULATORY CARE CENTRE XYZ (ACCXYZ), Malaysia. Majority complaints made by the hospital staff at level 1, state that they felt uncomfortable and suffering coldness due to very low temperature of centralizing air-conditioning especially during non-peak hours. Therefore, five parameters pointed to be measured based on the complaints from staff due to IAQ problems especially from Heating, Ventilating, and Air Conditioning (HVAC) system. By using 4 in 1 Meter Kit, three environmental parameters recorded such as air temperature (t), relative humidity (RH) and air velocity (AV) and the average result are 22.5°C, 57.7% and 0.02 m/s, respectively. Meanwhile, two chemical parameters recorded are carbon dioxide (CO2) with 875ppm and formaldehyde (CH2O) is 0.11ppm were measured using IAQ Calc model 7545 and Formaldehyde Meter Z-300 devices value within the standard. Thus, the result shows that the HVAC system affects the IAQ parameters in ACCXYZ building through a major impact on the temperature due to patient and staff environment and also to the operation of the sensitive machine in the building.

Thermal comfort is essential for students' wellbeing, health, and performance. A conducive classroom must consider the acceptable range of heat and its impact on student performance. The study aims to conduct a pilot test for the determination of thermal acceptability and student performance in existing Malaysian classrooms using physical and subjective assessments. The methodology requires physical measurement using KIMO AMI 310 instrument, as well as subjective assessment via satisfaction survey adapted from ASHRAE 55 and performance assessment adapted from WHO Neurobehavioral Core Test Battery (WHO NCTB). Physical measurement parameters, such as indoor temperature, air velocity, relative humidity, and prevailing mean outdoor temperature, were measured in parallel with subjective assessment of thermal acceptability and performance assessment. Three days of data collection were conducted in the secondary school located in Endau, Johor. There are three classes involved with a total of 46 students. Each class was equipped with two ceiling fans and both ceiling fans were regulated to the speed of four. The overall physical and subjective assessment procedure took approximately 60 minutes per classroom. The findings showed that all the investigated classes were in the range of acceptable operative temperature and complied with ASHRAE Standard 55 for both 80% and 90% acceptability limits. Pearson correlation analysis showed a small positive relationship between thermal sensation vote (TSV) and learning performance was obtained. The results also showed a higher performance score at the TSV value of -1 suggesting the students tend to have higher performance scores when they voted feeling slightly cool. Thus, the results of the pilot test gave new insight into the effective method to improve the methodology for the actual data collection.

Climate change is considered to be one of the biggest threats faced by nature and humanity today. The goal of this study is to predict future climate change for rainfall in the Upper Kurau Basin. In this research, the applicability of statistical downscaling model (SDSM) in downscaling rainfall in the Upper Kurau River basin, Perak, Malaysia was investigated. The investigation includes calibration of the SDSM model by using large-scale atmospheric variables encompassing the National Centers for Environmental Prediction (NCEP) reanalysis data. Rainfall data were derived for three 30-year time slices, 2020s, 2050s and 2080s, with A2 and B2 scenarios. A2 is considered among the "worst" case scenarios, projecting high emissions for the future. Unlikely, B2 projected a lower emission for the future and it is considered as "environmental" case scenarios. Results from simulation showed that during the calibration and validation stage, the SDSM model was well acceptable in regards to its performance in downscaling of daily and annual rainfalls. Under both scenarios A2 and B2, during the prediction period of 2010-2099, changes of annual mean rainfall in the Upper Kurau River basin would present a trend of increased rainfall in 2020s; insignificant changes in the 2050s; and a surplus of rainfall in the 2080s, as compared to the mean values of the base period. Annual mean rainfall would increase by about 33.7% under scenario A2 and increase by 27.9% under scenario B2 in the 2080s. Most of the areas of the Upper Kurau River Basin were dominated by increasing trend of rainfall and will become wetter in the future.