Although mostly invisible to the naked eye, the air we breathe is full of tiny particles of; chemicals, soil, smoke, dust or allergens, in the form of liquids, gases or solids. These minuscule airborne hazards are referred to as particulate matter, or PM.

Where does PM come from?

The amount of particulate matter in the air at any given time depends on the environment you find yourself in. These particles are released from a variety of sources both indoors and outdoors. When inside, PM levels are typically the same or lower than outside. 

Here are a few things that increase the levels of particulate matter floating around an indoor space: 

• coughing
• sneezing
• smoking
• cooking
• burning candles or fires
• using kerosene heaters
• diffusing essential oils
• cleaning using common chemical products 
• opening doors and windows to outdoor polluted environments
• using hairsprays, aerosol room freshers or deodorants 

Although there are hundreds of sources of outdoor air pollutants, the main contributors that increase the levels of particulate matter outdoors are:

• vehicles
• power generators
• industrial and agricultural emissions
• residential heating and cooking
• the manufacture and distribution of chemicals
• forrest fires

Why is it called 2.5?

The 2.5 in PM2.5 refers to the size of the pollutant in micrometers. 

What are the negative effects of exposure to pollutants.

Depending on how healthy you are in general, particle matter will have different long and short term negative health effects. When exposed to levels of between to moderate – hazardous range, one may experience the following effects:

• shortness of breath
• eye, nose and throat irritation
• excessive coughing and wheezing
• diminished lung function and lung disease
• diminished heart function, sometimes resulting in heart attack
• asthma attacks

PM2.5 also damages the environment by increasing acidity in the soil and water bodies. Which in turn affects their ability to produce food and support life.

What is considered a safe level of PM and how is it measured?

Pollution levels are generally measured on a scale of 0-500 called an Air Quality Index, or AQI:

Even at moderate levels, particulate matter can still be harmful to sensitive people. When air pollution levels are lower, the cardiovascular and respiratory health of a person will be much improved, both long and short term.