Understanding PM2.5 and Your Health

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May 14, 2019

As pollution and environmental policies continue to be the subject of international debate, you may hear the term “PM2.5” in the news. But what is PM2.5 and why should you care? Below, we’ve outlined the basics about this invisible pollutant and how it may be affecting your health.

What is Particulate Matter (PM)?

Particulate matter, or PM, is the name given to fine dust or liquid particles that are suspended in the air we breathe. These particles can come from natural sources (such as pollen), or from human activities (such as fuel combustion).

Large PM (think: sand, pollen, or smoke) can be seen by the naked eye, but PM with a diameter of less than 10 micrometers (or PM10) is often too small to be perceived. That said, when fine PM exists in exceptionally high concentrations (as it does in Delhi and Beijing), it can form a visible haze. Regardless of whether or not we notice any visual changes in our air quality, inhaling high levels of fine particulate matter can have serious impacts on our health.

PM2.5 Basics

When scientists, doctors, politicians, and environmentalists talk about particle pollution, they’re usually talking about PM2.5 (particulate matter with a diameter of less than 2.5 microns). This super-fine, largely invisible pollutant is more than 30 times smaller than a single stand of human hair.

Due to its microscopic size, PM2.5 is easily inhaled and has the potential to travel deep into our respiratory tracts. Once there, it can cause chronic irritation, trigger allergies and asthma, and increase our risk of developing serious infections and disease such as COPD. More recent studies have also linked high particulate pollution levels to fertility complications and reduced life expectancy rates.

Sources of PM2.5

Large, densely-populated cities tend to have higher PM2.5 levels because they’re epicenters of production and power consumption. In short, they're home to more vehicle traffic, construction projects, homes, businesses, and manufacturing facilities. That said, PM2.5 can rise in suburbs in proximity to high-pollutant areas or in relation to events like routine road paving, construction, or forest fires.

PM2.5 and Global Policy

As research continues to surface about the consequences of high PM2.5 levels, more countries have started to take notice. Because PM2.5 is airborne, it has quickly spread beyond cities and has begun to influence human health on a global scale. 

In recent years, some U.S. states and European countries have begun to take action by invoking PM2.5 standards, placing restrictions on business emissions, and enacting policies to reduce airborne pollution in metropolitan areas. In 2017, for instance, the U.K. announced a plan to eliminate speed bumps from city streets after a study showed that diesel cars emit 98 percent more nitrogen oxide when driving over a speed bump.

How Much is Too Much?

In the U.S., the Environmental Protection Agency (EPA) first published national PM2.5 standards in 1971. Since then, PM2.5 standards have been lowered (allowing for less particle pollution) as links between PM2.5 and serious adverse health effects have been studied further.

The most recent update to U.S. ambient PM2.5 standards was published in 2012. The newest standards maintained a PM2.5 daily standard of 35 microns per cubic meter (μg/m3), but lowered annual PM2.5 standards from 15 to 12 μg/m3. The European Union currently lists the annual PM2.5 standard at 25 µg/m3, but has outlined clear directives to lower exposure by 2020.

Although these universal standards serve as an important benchmark, PM2.5 levels don’t have to exceed daily EPA standards in order to effect our health and wellbeing. That’s especially true for “sensitive” populations (a group the EPA defines as “asthmatics, children, and elderly”) who are exceptionally prone to infection or have existing respiratory conditions.

It's even been shown that long-term exposure to excessive outdoor air pollution, and specifically to high levels of PM2.5, has at least a causal connection to a higher risk of serious illness or even death from COVID-19. More studies will need to be done to determine the exact role of air pollution to morbidity rates due to coronavirus, but the pandemic is drawing added attention to the relationship of outdoor air pollution and human health. 

In addition to the density of air pollution, our sensitivity to PM2.5 depends on the nature of the chemicals or organic compounds present. Although we know high levels of PM2.5 are unequivocally bad for our health, the exact level at which they become problematic and the severity of the health effects of ambient PM2.5 are still being explored. Less severe symptoms of elevated PM2.5 include chronic skin, eye, and throat irritation, headaches, persistent allergy symptoms, and more frequent respiratory infections.

How Does Your City Stack Up?

For the last 20 years, the American Lung Association has analyzed air quality data from across the U.S. and released their findings in an annual “State of the Air” report. In their latest edition, they rank the most polluted U.S. cities by ozone, short-term, and long-term particle pollution. California, a state known for progressive environmental policy, was home to eight of the top ten dirtiest cities on the list — making it clear that air pollution is a bigger problem than most West Coast natives imagined. For information about your zip code, you can use the EPA's AirNow index to track ozone and PM2.5 levels in your neighborhood.

Be in the Know

Is the “fresh air” you’re letting into your home truly healthy? Will opening a window help or hurt your asthma? Should you consider buying an air purifier, humidifier, or fan?

It’s easy to feel overwhelmed by information about air pollution if you don’t have the tools to change your environment. If you live in an area with high particle pollution, don’t panic. Monitoring your indoor air quality at home and work is one way to take control of your health and the air you breathe.

When it comes to air quality, knowledge is power. Awair can help you understand exactly what’s in your air and empower you to improve the air quality in your home, office, and beyond. To learn more about Awair and how it can help you make healthier decisions, simply follow the link below.