Particulate Matter (PM)

What do BREATHE|Smart monitors measure?


The monitors measures particle pollution (also known as “particulate matter”) in the air, specifically PM2.5 (particles less than 2.5 micrometers in diameter). These particulates are the deadliest form of air pollution due to their ability to penetrate deep into the lungs and blood stream.

Particle pollution consists of a mixture of solids and liquid droplets. Some particles are emitted directly; others form when pollutants emitted by various sources react in the atmosphere. 


What is PM2.5 and why is it harmful?

Particles come in a wide range of sizes. Those less than 10 micrometres (millionths of a metre) in diameter are so small that they can get into the lungs, where they can cause serious health problems.

• Fine particles. The smallest particles (those 2.5 micrometres or less in diameter) are called “fine” particles. Major sources of fine particles include motor vehicles, power plants, residential wood burning, forest fires, agricultural burning, some industrial processes, and other combustion processes.

• Coarse particles. Particles between 2.5 and 10 micrometres in diameter are referred to as “coarse.” Sources of coarse particles include crushing or grinding operations, and dust stirred up by vehicles traveling on roads. 

Fine particulate matter smaller than 2.5 micrometers, known as PM2.5, was the fifth-leading cause of death in the world in 2015, factoring in about 4.1 million global deaths annually. Current evidence suggests that PM2.5 alone causes more deaths and illnesses than all other environmental exposures combined.

With smoking on the decline, air pollution now causes more deaths annually than tobacco. While PM2.5 impacts everyone, people with breathing and heart problems, children and the elderly are most sensitive to it.

Exposure to PM2.5 has been shown to cause heart attack, irregular heartbeat, aggravated asthma, decreased lung function, increased respiratory symptoms, such as irritation of the airways, coughing, or difficulty breathing, cancer and premature death in people with heart or lung disease.


What are the health effects and who is most at risk?

Particles smaller than 10 micrometres in diameter can cause or aggravate a number of health problems and have been linked with illnesses and deaths from heart or lung disease. These effects have been associated with both short-term exposures (usually over 24 hours, but possibly as short as one hour) and long-term exposures (years).

Sensitive groups for particle pollution include people with heart or lung disease (including heart failure and coronary artery disease, or asthma and chronic obstructive pulmonary disease), older adults, and children. The risk of heart attacks, and thus the risk from particle pollution, may begin as early as the mid-40s for men and mid-50s for women.

• When exposed to particle pollution, people with heart or lung diseases and older adults are more likely to be admitted to hospitals, or in some cases, even die.

• Exposure to particle pollution may cause people with heart disease to experience chest pain, palpitations, shortness of breath, and fatigue. Particle pollution has also been associated with cardiac arrhythmias and heart attacks.

• When exposed to high levels of particle pollution, people with existing lung disease may not be able to breathe as deeply or vigorously as they normally would. They may experience symptoms such as coughing and shortness of breath. Healthy people also may experience these effects, although they are unlikely to experience more serious effects.

• Particle pollution also can increase susceptibility to respiratory infections and can aggravate existing respiratory


Actions To Protect Your Health From Particle Pollution

Good (0–50). None

Moderate (51–100). Unusually sensitive people should consider reducing prolonged or heavy exertion.

Unhealthy for Sensitive Groups (101–150). People with heart or lung disease, children and older adults should reduce prolonged or heavy exertion

Unhealthy (151–200). People with heart or lung disease, children and older adults should avoid prolonged or heavy exertion. Everyone else should reduce prolonged or heavy exertion.

Very Unhealthy (201–300). People with heart or lung disease, children and older adults should avoid all physical activity outdoors. Everyone else should avoid prolonged or heavy exertion. 


Source: US EPA.