Fine particles can come from various sources. They include power plants, motor vehicles, airplanes, residential wood burning, forest fires, agricultural burning, volcanic eruptions and dust storms.

Some are emitted directly into the air, while others are formed when gases and particles interact with one another in the atmosphere.

For instance, gaseous sulfur dioxide emitted from power plants reacts with oxygen and water droplets in the air to form sulfuric acid as a secondary particle.

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.

A study published in the Journal of the American Medical Association suggests that long-term exposure to PM2.5 may lead to plaque deposits in arteries, causing vascular inflammation and a hardening of the arteries which can eventually lead to heart attack and stroke. Scientists in the study estimated that for every 10 micrograms per cubic meter (μg/m3) increase in fine particulate air pollution, there is an associated 4%, 6% and 8% increased risk of all-cause, cardiopulmonary and lung cancer mortality, respectively.

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 Protect Yourself Against PM2.5

When the amount of PM2.5 is at unhealthy level, take these steps to reduce exposure and protect your health:

• Stay indoor and close all windows and openings that allow polluted air to enter, when possible.
• Turn on an energy recovery ventilator that is equipped with a HEPA filter. Only a HEPA filter can effectively remove fine particles from the air.
• When most or all windows are closed, do not burn candle, incense or operate energy recovery ventilator that emit smoke or gas to prevent harmful particles and gas (such as carbon monoxide) from building up. (Energy recovery ventilator is the ideal option which can reduce energy consumption of heating cooling system when ventilating).
• If you are a road warrior who must drive in all weather conditions, get a real air purifier for your car that comes with at least HEPA and activated carbon filters. A normal car filter can’t even remove traffic exhaust properly, let alone microscopic particles.
• If the air pollution is expected to last for many days, consider moving to an unaffected location.
• Boost your body’s resistance against PM2.5 by increasing your intake of some nutrients.
• If you must go outdoor, make it short and quick, and wear a N95 or higher face mask. Holtop electric anti-haze mask is specially designed for polluted area.