What does the term 'particulate matter' refer to in indoor air quality?

Particulate matter refers specifically to tiny solid or liquid particles that are suspended in the air. These particles can vary in size and composition and include dust, pollen, soot, smoke, and liquid droplets. In indoor air quality, particulate matter can originate from various sources, such as cooking, heating, smoking, and even outdoor air entering a building.

The presence of particulate matter can significantly impact health, as fine particles can penetrate deep into the lungs and bloodstream, leading to respiratory issues, cardiovascular diseases, and other health problems. Monitoring and controlling particulate matter is essential for maintaining good indoor air quality and ensuring a safe living or working environment.

The other options do not accurately define particulate matter: large objects that pollute the air do not fall under this category; specific types of gases are distinct from particles; and harmful noise levels relate to sound rather than particulate content in the air. Thus, the correct choice captures the precise definition of particulate matter relevant to indoor air quality.