Is Particulate Matter a Primary Pollutant? Your Pollution Questions Answered

Many people have heard particulate matter discussed, but they don’t know the specifics of it. Is particulate matter a primary pollutant? Where does it come from? How does particulate matter affect the environment? Let’s dive into this topic. 

What Is Pollution? 

Pollution occurs when harmful materials enter the environment, threatening the air, water, land and all the planet’s inhabitants. Although many people think of pollution as a substance, it can also be energy-related, such as from light or noise. Relatedly, pollution occurs from naturally occurring and foreign sources.

What Are the Types and Categories of Pollution? 

Scientists categorize pollution into three main types: Air, water and land. Particulate matter encompasses all of them. Additionally, there are primary and secondary pollutants. Those in the first group come directly from the source. Examples include: 

• Wildfires
• Car exhaust
• Factories
• Agriculture

Those sources result in primary pollutants such as:

• Carbon monoxide
• Volatile organic compounds
• Ammonia
• Nitrogen oxides

Then, secondary pollutants occur from interactions between previously emitted primary pollutants. Examples include: 

• Nitric acid
• Hydrogen peroxide
• Sulphuric acid
• Ozone

Is particulate matter a primary pollutant? The answer is more complex than some people might expect. That’s because it can be both a primary and secondary pollutant. Particulate matter comprises coarse or fine particles. 

Coarse particles are less than 10 microns in diameter, while fine particles are less than 2.5 microns in diameter. The source partially impacts the diameter, with landfills, burned waste and pollen more likely to be coarse, while the combustion of gas, oil and wood causes fine particulate matter. 

When Is Particulate Matter a Primary Pollutant?

What determines whether particulate matter is a primary or secondary pollutant? When it enters the atmosphere as solid or liquid particles, it’s a primary pollutant. However, particulate matter is a secondary pollutant when it forms due to chemical reactions between atmospheric gasses.

Common sources of particulate matter as a primary pollutant include: 

• Gas and diesel-powered vehicles
• Wildfires
• Road dust
• Agricultural facilities
• Fireplaces and wood stoves

In contrast, power plants and some industrial processes are significant sources of particulate matter as a secondary pollutant. Statistics link household and ambient air pollution to 6.7 million deaths per year, emphasizing the need to minimize pollution where possible. 

How Does Particulate Matter Affect the Environment? 

Particulate matter can have various impacts on the environment. For example, it can alter light absorption and scattering in the atmosphere, interfering with visibility. Haze is a familiar example. 

Additionally, environmental characteristics — such as wind — can determine how far particulate matter travels from the source and how it settles. The results can: 

• Deplete the soil of nutrients
• Contribute to acid rain
• Alter waterways’ nutrient composition
• Harm ecosystem diversity
• Damage crops and forests

Particulate matter can also discolor and damage statues and cultural artifacts. One preventive measure is to apply water-resistant coatings that can withstand the elements. 

An interesting example of how human-caused particulate matter contributes to environmental pollution came when researchers studied the Salton Sea, a Californian lake. Water runoff from agricultural facilities fed the lake for nearly 100 years. Then, once people in some areas of the state faced water shortages around 2011, an agreement — which continues to this day — resulted in water getting sent to San Diego for urban applications. That change resulted in the agricultural sources feeding the Salton Sea to reduce their consumption and the associated runoff. 

Researchers recently confirmed it also increased particulate pollution due to the Salton Sea’s exposed lakebed, which adds dust to the environment during windy days. They believe this increased pollution especially affects the area’s disadvantaged communities. 

The team divided the exposed lakebed into 1-square-kilometer grids and gathered daily air pollution data for more than two decades. They also relied on an advanced physics model to calculate wind movement and particle sizes, learning how the dust moved over time. The results showed elevated dust transfers after 2011 and that communities living closer to the affected areas were most impacted. In some cases, the dust traveled up to 100 miles from the source. 

How Does Particulate Matter Harm Humans? 

Scientists are also concerned about the impact of particulate matter on human health. People can inhale the particles, introducing them into their lungs. Some also reach the bloodstream.  Ongoing research shows particulate matter can adversely affect the cardiovascular system and increase people’s risk of diseases that could worsen their quality of life or shorten how long they live. 

However, the onset of problems after exposure is not necessarily quick. Researchers found a direct link between air pollution in childhood and bronchitis symptoms in adults. They concluded the most effective action to mitigate these effects would occur at the policy level, particularly because of the limited effects caused by individuals’ actions. 

Although many people may assume they’re relatively safe if they can manage their activities to avoid prolonged exposure, research shows that is inaccurate. A group tracked the number of premature deaths attributable to short-term particulate matter exposure, which lasted from hours to days. The researchers explained that such incidents can occur through short, concentrated bursts caused by sources such as sudden wildfires. 

Their findings showed such short-term exposures cause more than 1 million worldwide deaths every year, with some areas more affected than others. For example, more than 62% of those deaths occurred in Asia, followed by Africa in a relatively distant second at 17%. 

How Can You Reduce Particulate Matter Exposure? 

People should become more aware of particulate matter sources and limit them as much as possible. Getting familiar with local air quality levels and associated alerts is a good start. It’s then wise to stay indoors when practical if the air quality is unhealthy. Additionally, individuals should consider taking preventive measures — such as wearing a respirator — when going outside.

They should also understand how tobacco smoke, candles and frying or broiling food can cause indoor particulate matter. Air cleaners can reduce the effects. Similarly, a window-mounted air conditioner set on a recirculating setting makes particulate matter less severe for those impacted. Alternatively, portable fans enable recirculation, but people must refrain from using whole-house fans since they pull in outdoor air.

Making Sense of Particulate Matter Exposure

Particulate matter exposure is unavoidable, whether as a primary or secondary pollutant. However, when people understand its sources, impacts and preventive measures, they can take decisive steps to keep themselves and their families safe.