PM 2.5 - Something You Need to Know about Air Pollution

What is PM2.5

PM2.5 refers to atmospheric particulate matter (PM) that have a diameter of less than 2.5 micrometers, which is about 3% the diameter of a human hair. PM2.5 is also known as fine particulate matter  (2.5 micrometres is one 400th of a millimetre).

Where Do PM2.5 Come From

There are outdoor and indoor sources of fine particles. Outside, fine particles primarily come from car, truck, bus and off-road vehicle (e.g., construction equipment, snowmobile, locomotive) exhausts, other operations that involve the burning of fuels such as wood, heating oil or coal and natural sources such as forest and grass fires. Fine particles also form from the reaction of gases or droplets in the atmosphere from sources such as power plants. These chemical reactions can occur miles from the original source of the emissions. Fine particles can be carried long distances from their source, events such as wildfires or volcanic eruptions can raise fine particle concentrations hundreds of miles from the event.

PM2.5 is also produced by common indoor activities. Some indoor sources of fine particles are tobacco smoke, cooking (e.g., frying, sautéing, and broiling), burning candles or oil lamps, and operating fireplaces and fuel-burning space heaters (e.g., kerosene heaters).

Why Are PM2.5 Dangerous

Since they are so small and light, fine particles tend to stay longer in the air than heavier particles. This increases the chances of humans and animals inhaling them into the bodies. Owing to their minute size, particles smaller than 2.5 micrometers are able to bypass the nose and throat and penetrate deep into the lungs and some may even enter the circulatory system.

Studies have found a close link between exposure to fine particles and premature death from heart and lung disease. Fine particles are also known to trigger or worsen chronic disease such as asthma, heart attack, bronchitis and other respiratory problems.

Children, older adults and those who are suffering from lung and/or heart disease are especially vulnerable to the adverse effects of fine particles in the air and should take special precautions when ambient PM2.5 crosses unhealthy levels.

How to Read PM2.5 Readings

Due to the many adverse effects fine particles can inflict on a large number of people, PM2.5 is one of the major pollutants closely monitored by health authorities around the world. You will most likely come across a dedicated column for PM2.5 alongside the Air Quality Index (AQI), Pollutants Standards Index (PSI) or the air quality standards adopted by your country.

On a very clear and non-hazy day, the PM2.5 concentration can be as low as 5 μg/m3 or below. The 24-hour concentration of PM2.5 is considered unhealthy when it rises above 35.4 μg/m3.

Why 24-hour and not a shorter duration when evaluating the health impact of fine particles? This is because the potential damage caused by air pollutants depends not just on the concentration, but also on the duration of exposure. The longer you are exposed to PM2.5, the higher the risk of developing adverse effects caused by the exposure. That’s why a 24-hour measurement is a better reflection of the health effects of fine particles than say a three-hour reading.

The table below will give you a sense of what levels of PM2.5 are harmful and the appropriate precautions you need to take. It is based on the air quality standards for particle pollution published by the U.S. Environmental Protection Agency.

24-Hour PM2.5 Standard (μg/m3)

Source: U.S. Environmental Protection Agency

7 Tips to Improve Indoor Air Quality in Your Home

Tip #1: Opening the windows

Open the windows for 5 to 10 minutes. Do it on an everyday basis, even if you don’t know exactly how polluted the air is inside your home. You should also do it when you or someone else engages in an activity prone to deteriorate indoor air quality.

Tip #2: Tell smokers to light up outside

• Stop smoking indoors.

• Ask that smokers go outside.

Tip #3: Keep a clean and tidy home

• Use a doormat to prevent dirt from entering into your home and/or ask people to take off their shoes when they visit you.
• Try vacuuming and mopping floors at least once a week.

Tip #4: Keep humidity between 30% to 50%

• Track humidity levels.
• Use a dehumidifier to effectively control moisture and allergens.
• Remember to open the window when cooking or when you take a shower or bath (or right after if you are easily cold).
• Make sure there are no water leaks in your home.
• If you have a clothes dryer, open the window when it is venting.
• Remember to empty your air conditioner’s drip pans.

Tip #5: Stay away from synthetic fragrances

• Arrange slices of lemon on a plate to delicately perfume the air in a room.
• Use baking soda in a small bowl to eliminate odors (it works particularly well in fridges).
• Choose fragrance-free products, or products with scents of natural origin for your laundry and cleaning needs.
• Stop using aerosol spray products that create a mist of liquid particles (hair sprays, air fresheners…)

Tip #6: Place an air-filtering plant in your home

• Get an English ivy (Hedera helix) or a variegated snake plant (Sansevieria trifasciata “Laurentii”), which share the same pollutant-blocking skills. They are great to filter out benzene, formaldehyde, trichloroethylene, xylene and toluene.
• Get a peace lily (Spathiphyllum “Mauna Loa”) or a florist’s chrysanthemum (Chrysanthemum morifolium). These two are even more effective: they filter out all of the above, as well as ammonia! Be careful not to ingest either the English ivy’s or the peace lily’s leaves and berries, as they are toxic.

Tip #7: Monitor your indoor air quality

Get a PM2.5 air quality detector and monitors the real time air quality index of your home.

Ecowitt PM2.5 Air Quality Monitor