Related Experiment Video
Updated: Aug 23, 2026

Symptom Assessment of Patients with Allergic Rhinitis Using an Allergen Exposure Chamber
Published on: March 3, 2023
Evaluation of indoor air quality using the decibel concept. Part II-ventilation for acceptable indoor air quality
1Technical University, Prague, Czech Republic.
Abstract:
Weber-Fechner's law concerning the perception of sound by man with time expressed as a logarithmic function can also be used for the odour constituent used in the evaluation of indoor air quality in buildings. A new unit dB (odour) based on the concentration of Total Volatile Organic Compounds (TVOC) is proposed as it is currently the basis for determining the air change rate. On the Psycho-Physical Scale according to Yaglou, the weakest odour that can be detected by the human smell sensors is equal to one and corresponds to the lower limit of percentage dissatisfaction (PD) of 5.8% and a threshold concentration (TVOC) of 50 micrograms/m3-0 dB (odour). The upper limit is determined by the initial value of toxicity TVOC -25,000 micrograms/m3-135 dB (odour). Optimal values corresponding to PD = 20% (according to EUR 14449 EN) and admissible values corresponding to PD = 30% (see Part I of this paper) are proposed, therefore the same values used to evaluate noise can be used to evaluate air quality and additionally the contribution of individual constituents (at present acoustic and odour) to the overall quality of the environment can be ascertained.
Related Concept Videos
Sound Intensity Level
The human ear can perceive an extensive range of sound intensity, necessitating the use of the logarithmic scale to define a physical quantity—the intensity level. It is a ratio of two intensities and hence a...
Assessment of Ventilation I: Respiratory Rate
A Ventilation assessment is critical for monitoring a patient's health status. Respiration, one of the most accessible vital signs, provides insights into the function of numerous body systems and can indicate serious health issues, such as brainstem injuries from head trauma.
Critical Guidelines for Assessing Ventilation:
Respiratory Volumes and Capacities I
Assessment of Ventilation II: Respiratory Depth and Rhythm
Respiratory depth measures the volume of air inhaled or exhaled during a breath. It can vary from shallow to deep and typically remains consistent when a person is at rest or asleep. Occasionally, individuals will automatically inhale deeply, known as sighing, which inflates the lungs with more air than normal breathing.
To assess respiratory depth, observe the degree of chest excursion or movement:
Respiratory Volumes and Capacities
Mechanical Ventilation II: Invasive Ventilation
Negative-Pressure Ventilators
Negative-pressure ventilators create a vacuum around the chest or body to draw air into the lungs, simulating breathing. This method does not require an...

