Updated on:
Particulate matter (PM) is a mix of tiny solids and liquid droplets in the air. The smallest particles, PM2.5, can reach deep into the lungs and even enter the bloodstream, raising the risk of heart and lung disease.
What is particulate matter (PM)?
PM is a mixture of microscopic solids and liquid droplets suspended in air. It is categorized by aerodynamic diameter: coarse (PM10, ≤10 µm), fine (PM2.5, ≤2.5 µm), and sometimes ultrafine (PM0.1, ≤0.1 µm).
Smaller particles pose greater health risks because they penetrate deeper into the respiratory system, and some can enter the bloodstream.
Understanding the Effect of Humidifiers on Particulate Matter (PM) Sensors
What are PM2.5 and PM10, and why does size matter?
PM10 includes particles small enough to be inhaled into the lungs; PM2.5 is the fine fraction that reaches the deepest regions and can translocate into circulation. The finer the particle, the higher the health concern.
WHO’s health‑protective guideline levels for PM2.5 are 5 µg/m³ annual and 15 µg/m³ 24‑hour, reflecting evidence that lower is better for health.
Where does particulate matter come from?
PM comes from direct emissions (primary) and atmospheric formation (secondary). Primary PM sources include traffic exhaust, industry, wildfires, dust, construction, and cooking; secondary PM forms from reactions of SO₂, NOₓ, NH₃, and VOCs in the air.
Indoors, common sources are cooking, smoking, candles/incense, wood‑burning, and unvented heaters; outdoor PM infiltrates through leaks and open windows.
Why is particulate matter harmful to health?
Short‑term exposure can trigger asthma symptoms, heart attacks, and hospitalizations; long‑term exposure increases risks of cardiovascular and respiratory disease and premature death.
Air pollution dominated by PM2.5 was linked to 8.1 million deaths globally in 2021, making it the second leading risk factor for death worldwide.
How does particulate matter affect indoor air quality?
Indoor PM levels reflect both indoor activities and the amount of outdoor pollution that enters inside. Cooking, especially frying and grilling, can produce short‑term PM2.5 spikes far above background levels without capture ventilation.
Improving source control, ventilation (when outdoor air is clean), and filtration lowers indoor PM2.5 and improves comfort and health.
What levels of PM2.5 are considered safe?
There is no known safe threshold for PM2. 5. The lower the better. WHO’s guideline values are 5 µg/m³ annual and 15 µg/m³ 24‑hour.
The U.S. EPA’s outdoor health‑based standards are 9 µg/m³ annual and 35 µg/m³ 24‑hour.
In the EU, the 2024 directive tightens the annual PM2.5 limit to 10 µg/m³ by 2030.
How can I measure particulate matter around me?
Regulatory monitors use reference methods, while consumer devices typically use optical light‑scattering (laser/LED) to estimate PM mass from particle counts. Accuracy depends on particle type, humidity, and calibration.
Independent evaluations show that some low‑cost sensors track reference monitors more closely when using correction factors.
How can I reduce exposure to particulate matter?
Control sources (especially cooking), ventilate with clean outdoor air when available, and filter the air effectively. Portable HEPA air cleaners remove ≥99.97% of 0.3 µm particles and are highly effective for PM2.5; in central HVAC, aim for MERV 13 or higher where the system allows.
During wildfire smoke or smog episodes, close windows, set systems to recirculate, run HEPA or MERV 13+ filtration continuously, and seal leaks.
What’s the difference between dust and particulate matter?
“Dust” usually refers to larger, visible particles (often >10 µm) that settle quickly. “Particulate matter” includes both coarse and fine fractions—down to PM2.5 and ultrafine—that stay airborne longer and carry greater health risks.
How does particulate matter impact the environment?
PM reduces visibility (haze), soils buildings, and deposits on ecosystems; some components, like black carbon, also warm the climate by absorbing sunlight.
Quick reference: PM2.5 ranges and practical actions
- WHO guideline: 5 µg/m³ annual; 15 µg/m³ 24‑hour (health‑protective).
- US standards: 9 µg/m³ annual, 35 µg/m³ 24‑hour (outdoor).
- Cooking can produce short‑term indoor PM2.5 spikes without capture ventilation; use vented range hoods.
- Wildfire/smog: close windows, switch to recirculation, run HEPA/MERV 13+, and seal leaks.
Conclusion: A calm, practical plan for lower PM
Treat particulate matter as both a daily habit and a building‑system challenge. Capture cooking emissions, avoid indoor smoke, and upgrade filtration. When outdoor air is clean, ventilate; when it’s smoky, seal and filter. Measure with a reliable PM2.5 monitor and adjust in real time.
FAQ: Particulate matter
What is particulate matter in simple terms?
It’s a mix of tiny solid and liquid particles in the air. The finest, PM2.5, can reach deep into the lungs, and some can enter the bloodstream.
What is PM2.5, and why is it so harmful?
PM2.5 (≤2.5 µm) penetrates to the deepest lung regions and is linked to heart and lung disease and premature death.
What do PM10 and PM2.5 mean?
They’re size cut‑offs: PM10 (≤10 µm) includes coarse particles; PM2.5 (≤2.5 µm) includes fine particles with higher health risk.
How do I get rid of particulate matter indoors?
Control sources (especially cooking), ventilate with clean outdoor air, and use HEPA purifiers or MERV 13+ HVAC filters.
What releases particulate matter in a house?
Cooking, smoking, candles/incense, fireplaces/wood stoves, and unvented heaters, plus outdoor PM infiltration.
How long does particulate matter stay in the air?
Outdoors, days to weeks depending on weather; indoors, hours or longer without ventilation/filtration.
Can air purifiers help with particulate matter?
Yes. Portable HEPA purifiers are effective for PM2.5 when properly sized for the room.
Which countries have high PM2.5 levels?
The highest exposures are in parts of Asia, Africa, and the Middle East; many countries exceed WHO guideline levels.
Can PM2.5 be removed from the body?
The body clears some particles, but prevention is best—reduce exposure with filtration and clean air.
What diseases does PM2.5 cause?
PM2.5 exposure is linked to heart disease, stroke, COPD, lung cancer, and asthma exacerbations.
