# Particle Number of Aerosol in Specific Conditions of Biotechnology Laboratory Cleanroom
## 1 Introduction  
The control of airborne particles and biological contaminants is a key factor in various industries to avoid product defects, ensure process quality, and protect personnel and the environment ([PERSON] et al., 2020) [1]. Additionally, cleanrooms and controlled environments are spaces where air pollution and thermohygrometric parameters are strictly controlled. Airborne particulate monitoring is mandated as part of good manufacturing practices ([PERSON] et al., 2012) [2]. [PERSON] (2015) asserts that pharmaceutical manufacturing, both non-sterile and especially sterile processing, should be designed and manufactured in areas that minimize the potential for contamination by controlling environmental cleanliness and minimizing the possibility of personnel introducing contamination into the process. [PERSON] et al. (2005) found that the airflow characteristics of a cleanroom for the photolithography process are largely influenced by the porosity of the access panel and the setting of the dampers, and that cross-contamination varies with source location and time as a result of the concentration ratio [3,4]. Most electronic cleanrooms are populated with process tools that emit high-temperature heat and particles. This accumulation of heat and particles within cleanrooms causes higher-than-normal airflow resistance and reduces cleanroom quality ([PERSON] et al., 2011) [5]. The main purpose of cleanrooms is to prevent the contamination of cleanrooms with microparticles in order to ensure the reliability of precision processes and the associated safety of personnel. Cleanrooms can be found in high-precision industries (e.g., TFT LCDs), semiconductors, microelectronics, and biotechnology ([PERSON] et al., 2011) [6]. [PERSON] et al. (2022) state that humans are the mainsource of particle contamination in biological cleanrooms [7]. The emitted particles can carry microorganisms and these can greatly affect cleanliness. An aerosol is defined as a suspension of a liquid or solid in a gas, and the size of aerosol particles ranges from 0.001 \(\upmu\)m to 100 \(\upmu\)m ([PERSON] et al., 2014) [8]. The particles can be of organic or inorganic origin. Inorganic particles include dust from the weathering of rocks; chemical fibers from clothing; dust from tire wear; unburned residues from liquid, gaseous, and solid fuels; dust from the wear or demolition of buildings; and, for example, cosmic dust ([PERSON], 1975, states that an estimated 14.3-106 tonnes of cosmic dust settle on Earth each year) [9]. Organic dust includes, but is not limited to, residues of plant or animal origin (e.g., human skin debris), natural fibers, bacteria, viruses, fungi, molds, etc. Aerosols generated in the outdoor environment can enter the indoor environment in three basic ways: natural ventilation, mechanical ventilation, and infiltration ([PERSON] and [PERSON], 2011) [10]. The concentration and quality of aerosols can vary significantly from place to place. This is influenced by the activities that take place in the indoor environment or occur near the facility where the indoor environment is being assessed. It also depends on how the building's ventilation system is designed and whether an air purification system is in place ([PERSON] et al., 2020) [11]. Low aerosol concentrations in indoor air are essential for many areas of human activity. These include the manufacture of sensitive electrical components and precision mechanical products, the pharmaceutical industry, the medical industry, and laboratories ([PERSON] et al., 2007) [12]. In the manufacture of sensitive electrical components, high concentrations of particles can lead to quality degradation or even failure or malfunction. In the pharmaceutical industry, this can lead to the contamination of drugs; in healthcare, it can increase the likelihood of the infection of patients in the operating room; and in laboratories, it can falsify experimental results ([PERSON] et al., 2015) [13].