Understanding Air Quality Parameters PM2.5 and PM10 Explained

Air quality has a direct impact on our health and environment. Among the many factors that determine air quality, PM2.5 and PM10 are two of the most important parameters. These terms refer to tiny particles suspended in the air, but their differences and effects are often misunderstood. This post will clarify what PM2.5 and PM10 mean, why they matter, and how they affect us.

Microscopic view of PM2.5 and PM10 particles in the air

What Are PM2.5 and PM10?

PM stands for particulate matter, which includes solid particles and liquid droplets found in the air. These particles vary in size, composition, and origin. The numbers 2.5 and 10 refer to the diameter of the particles measured in micrometers (µm).

• PM10 includes particles with a diameter of 10 micrometers or less. These are often called coarse particles.

• PM2.5 includes finer particles with a diameter of 2.5 micrometers or less.

  
  

To put this in perspective, a human hair is about 70 micrometers thick, so PM10 particles are roughly 1/7th the width of a hair, and PM2.5 particles are even smaller.

Sources of PM2.5 and PM10

Both PM2.5 and PM10 come from natural and human-made sources, but their origins differ somewhat:

• PM10 sources

- Dust from roads, construction sites, and agriculture

- Pollen and mold spores

- Sea spray and volcanic ash

• PM2.5 sources

- Combustion processes such as vehicle exhaust, power plants, and industrial emissions

- Burning of wood, coal, and other fuels

- Secondary particles formed in the atmosphere from gases like sulfur dioxide and nitrogen oxides

Because PM2.5 particles are smaller, they often come from combustion and chemical reactions, while PM10 includes larger dust and biological particles.

Why PM2.5 and PM10 Matter for Health

The size of these particles determines how deeply they can penetrate into the respiratory system:

• PM10 particles can enter the nose and throat but usually get trapped before reaching the lungs. They can cause irritation, coughing, and worsen conditions like asthma.

• PM2.5 particles are small enough to reach deep into the lungs and even enter the bloodstream. This can lead to serious health problems such as heart disease, lung cancer, and respiratory infections.

  
  

Studies show that long-term exposure to high levels of PM2.5 increases the risk of premature death and chronic diseases. Children, the elderly, and people with pre-existing health conditions are especially vulnerable.

Measuring and Reporting PM2.5 and PM10

Air quality monitoring stations use specialized instruments to measure the concentration of PM2.5 and PM10 in micrograms per cubic meter (µg/m³). These measurements help determine the air quality index (AQI), which informs the public about pollution levels.

• Typical safe limits

- PM10: The World Health Organization (WHO) recommends a 24-hour mean limit of 50 µg/m³.

- PM2.5: The WHO recommends a 24-hour mean limit of 25 µg/m³.

Cities with Poor Air Quality

Many cities around the world face challenges in maintaining acceptable levels of PM2.5 and PM10. Below are some examples:

• Delhi, India - Frequently experiences hazardous air quality levels due to vehicle emissions, industrial pollution, and seasonal crop burning.

• Beijing, China - Struggles with high levels of PM2.5, especially during the winter months when coal burning for heating increases.

• Lagos, Nigeria - Faces significant air quality issues due to traffic congestion, industrial emissions, and waste burning.

• Los Angeles, USA - While improvements have been made, the city still experiences elevated PM10 levels due to traffic and geographical factors.

• Kabul, Afghanistan - Often has high PM2.5 levels due to dust storms, vehicle emissions, and the burning of low-quality fuels.

• Dhaka, Bangladesh - Known for its severe air pollution, primarily from construction activities, traffic, and industrial emissions.

• Karachi, Pakistan - Faces significant air quality challenges due to industrial emissions, vehicle exhaust, and dust.

These cities exemplify the ongoing struggle to manage air quality effectively, often exacerbated by urbanization and economic activities.

Practical Ways to Reduce Exposure

Understanding PM2.5 and PM10 helps individuals take steps to protect themselves:

• Stay indoors on high pollution days, especially if you belong to sensitive groups.

• Use air purifiers with HEPA filters to reduce indoor particulate matter.

• Avoid outdoor exercise near busy roads or industrial areas during peak pollution times.

• Keep windows closed when outdoor air quality is poor.

• Support policies and practices that reduce emissions from vehicles and industries.

  
  

The Bigger Picture: Environmental Impact

Beyond health, PM2.5 and PM10 affect the environment:

• They reduce visibility, causing haze and smog in urban and rural areas.

• Particles can settle on soil and water, affecting ecosystems and agriculture.

• Some particles contain toxic substances that accumulate in the food chain.

  
  

Reducing particulate pollution benefits both human health and the environment.

City skyline showing smog caused by particulate matter pollution

Final Thoughts on PM2.5 and PM10

PM2.5 and PM10 are key indicators of air quality that directly affect health and the environment. Knowing the difference between these particles helps us understand pollution risks and take informed actions. Monitoring air quality and reducing emissions remain essential to improving the air we breathe.