Indoor Air sciences CSMI Practice Exam

Respirable particles are defined as those less than what size?

1. 0.1 microns

2. 21 microns

3. 11 microns

4. 1 micron

The correct answer is: 11 microns

Respirable particles are typically defined as those that are 10 microns or less in diameter, with a focus on particles that can penetrate deep into the lungs when inhaled. In pulmonary health discussions, the threshold often considered is 2.5 microns, which refers to fine particulate matter that can have significant health effects. In this context, the correct response regarding the size of respirable particles is that they are less than 1 micron in diameter. Particles of this size can easily bypass the upper respiratory system and reach the alveolar region of the lungs, leading to various health problems. This understanding is crucial in indoor air quality assessments and in mitigating health risks associated with airborne pollutants. Other options, such as particles measuring 0.1 microns, 21 microns, and 11 microns, do not align with the standard definition of respirable particles. Particles that are 21 microns and larger are generally filtered out by the upper respiratory tract and thus are not considered respirable. Understanding the size classification helps in designing effective air filtration solutions and improving indoor air quality.