Air quality in an RMG factory must be at a safer level to ensure the good health and well-being of the workers. Safe and healthy environments are targets of Sustainable Development Goals (SDG) 8.8 & 3.9, respectively. So, regular monitoring and monitoring-based initiatives should be taken by the compliance team. To facilitate this monitoring process, ESP8266 mediated dust, humidity, temperature, and carbon monoxide (CO) gas sensors can play an unprecedented role, especially for local RMG manufacturers, as they are not aware enough in most of the cases. In this study, we utilized a dust sensor (GP2Y1010AU0F), a combined humidity-temperature sensor (DHT22), and a CO gas sensor (MQ-7) to determine dust amounts, humidity, temperature, and CO level in three sections of an RMG factory, such as cutting, sewing, and finishing. Particularly, the average dust amount values are approximately 65, 198, and 32 µg/m³ in the cutting, sewing, and finishing sections, while the standard value is 20-30 µg/m³ for good quality of air as per PM10. According to WHO, this working environment can be labeled as weak, very weak, and moderate for the cutting, sewing, and finishing sections, respectively. Other results are approximately 29°C, 63%, and 86 ppm in the case of humidity, temperature, and CO concentration. However, the solutions may vary as per previous studies on dust sensors, like exhaust fans, water spray, etc. In addition, this study represents the existing poor environmental scenario in Bangladesh garment factories to generate as much awareness as possible. As a part of the process, this study focuses on the utilization of a cost-effective microcontroller system with a ThingSpeak cloud-based application.