I’ve been thinking about my lungs lately, especially as we recently passed the third anniversary of the week the world shut-down due to a microscopic lung invader. Don’t worry, I’m not going to preach about COVID. But I’m going to forego the usual travel blog this week to let my science nerd out. If you’re not into this, that’s fine, but I hope you’ll take a moment to at least wonder why millions of people in the world are still wearing masks, and why wearing a mask, for most people, is simply not the big deal that it is in the USA.

I’m sure I’ve posted photos of people wearing masks on the streets in Vietnam, usually on motorbikes. I’m even wearing one myself in some photos. You might think there must be a big COVID problem, or that the government is really cracking down on mask wearing, but it really has nothing to do with the pandemic. Certainly, there are a few public places where masks may still be required, but masking has long been a voluntary practice in Vietnam, and in many parts of Asia, particularly outdoors. It’s actually one of the ways that Vietnam dealt so smoothly with the initial phases of the pandemic. When those of us in the US were scrambling to try to figure out how to make masks out of old bedsheets and t-shirts, pretty much anyone who rides a motorbike in Vietnam (which is pretty much everyone) already had a set of masks handy.

There are a couple of reasons people wear masks: the first, is to protect against particulate matter from vehicle emissions, especially because so many people ride motorbikes and are receiving the direct effect of those emissions in their faces every time they hit the roads. The second is for protection from the intense tropical UV sunlight. I admit, especially after having some sort of spot of unknown nature removed from my nose last summer, I put my mask on when I’m out walking at midday and the sun is bright – this is in addition to the sunscreen. But the mask also helps with the roadside fumes, dust from building demolitions and construction, cigarette smoke, smoke from the many grills that line the street, especially at mealtimes, and trash or biomass burning.

You might thinking, “Ugh. How horrible to walk in a place where you can’t breathe the air – where the air and the sunlight might give you cancer, or asthma, or any number of horrible lung diseases!”

But let’s dig a little deeper: What is air pollution? (Nerd alert! Stay with me here!)

While there are many air pollutants, there are a few primary pollutants we keep track of when we measure air quality: ozone, PM2.5 and PM10. PM stands for Particulate Matter. PM10 includes airborne particulate matter less than 10 micrometers (µm), or 10^-6 meters. You might be thinking that sounds really small, and it is. Imagine something 1000 times smaller than the thickness of your credit card. However, in the world of pollutants and viruses, that’s fairly large.

Most masks can stop particulates that size, as long as you don’t have big gaps around the bridge of your nose or along your cheeks. PM2.5 includes particles less than 2.5µm. Coronavirus is much smaller than PM2.5 (about 50-140 nanometers). Most N95, KN95, FFP2 masks can stop about 95% of PM2.5 as well as coronavirus (again, having a good fit is important), so they will protect you from some air pollution.

Vietnam certainly has an air pollution problem. The country ranks somewhere around 33rd or 36th most polluted country in the world, depending on which ranking system you look at. It ranks a bit better than in Croatia or Serbia, and the air in Vietnam is much better than the air you would find in India or, especially, Bangladesh, which has the worst air quality in the world. Also, air quality varies from day to day, depending on weather patterns, time of the year, and where you are in the country. Hanoi ranks as the 7th most polluted city in the world. Ho Chi Minh City is not as bad.

The transportation system is the primary cause of poor air quality in Vietnam, with 58 million bikes on the road, and many cars as well, many are older vehicles and do not comply with modern emission standards. Many people in the country use biomass cooking stoves (think of a grill on a street corner. Street food vendors everywhere use them). And in agricultural regions, there is heavy burning of agricultural biomass, such as straw, pine needles, sugar cane chaff, etc. Air quality declines further when the Trade winds slacken a bit and smoky air from burning of rice stalks in Cambodia and Thailand makes its way across to Vietnam.

Here in the mountains of Dalat, the air is generally a bit better than it is in the big cities. In fact, through January and February, we enjoyed clear blue (or cloudy) skies and striking sunsets. But in early March, the local landfill caught on fire, and it has been burning steadily since then. Especially as the air grows still in the evening (meteorologists will recognize this as the development of the nighttime ‘boundary layer’, the layer of air that settles near the ground in the absence of daytime heating), smoke drifts down from the landfill and settles over the city center. The quantity of smoke is well into the ‘unhealthy’ zone sometimes, and I can occasionally smell it in my apartment even with the windows closed.

So, yes, even places with beautiful air are prone to getting choked by bad air.

According to IQAir (a Swiss company that, I think, is trying to sell air purifiers), the average PM2.5 concentration in Vietnam is 4.9 times higher than the World Health Organization (WHO) annual air quality guidance value. 

Now you’re thinking ‘Yikes! Yes, wear a mask!’ But here’s one more statistic:

The same company reports that PM2.5 concentration in Denver, Colorado is 5.8 times higher than the WHO annual air quality guidance value.

That’s right. My fellow Coloradoans might be nodding right now, thinking, “Yep, the air gets bad here.” Apparently, it’s worse in Greeley than in Denver (but I don’t have the numbers). Who are the biggest polluters in Colorado? Coal-fired power plants and the crude oil refinery north of Denver. Transportation and stagnant air – especially in the summer – are additional culprits. I was once interviewed by a local newspaper about the poor air quality in Northern Colorado, and I mentioned all of those things, but the only thing that made it to the paper was the part about stagnant air. As if pollution just floats around in stagnant air without actually coming from a particular source.

We are also very prone to large fires in Colorado – fires in the mountains that send a rain of ash downstream over the Plains. Not only do you have to worry about breathing the smoke, but that stuff is painful when it gets into your eyes.

In the US, we measure air quality according to the Air Quality Index (AQI). Colorado is often in the ‘yellow’, or ‘moderate’ range, unless there is a fire in the mountains, which is a common event in late summer or early fall. Vietnam also falls in the ‘moderate’ yellow range on the AQI. Colorado is just higher on the scale (ie, worse air quality), especially if we compare with the city of Dalat (when the landfill is not on fire).

So I found myself wondering: why am I not wearing a mask on the streets of Greeley?

In Vietnam, I’m usually walking on very busy streets, with hundreds of motorbikes whizzing past every minute. Most of the motorbikes here are fairly modern, less than 20 years old, which means they meet modern emission standards. But there are a lot of them. And there are quite a few older vehicles. At least once a day I’m engulfed in a cloud of blue and black smoke from an older vehicle or bike trying to chug its way up one of Dalat’s streets. If you’re on a motorbike, you’re right in the middle of it all.

But at least getting smoked out while walking along a street is not done intentionally here, as it sometimes is back home. I’ve been smoked out enough while riding my bike in Greeley by big trucks with billowing black clouds from their tailpipes. Still, the streets I walk along are much quieter back home, at least, where I live. It’s easy to avoid the busy street, mostly because my walks are generally just for pleasure, not because I need to visit the phone store or pick up a 5-liter bottle of water to carry home. I have the privilege of driving my car to the store, which has a cabin air filter that I make sure to use when I wait at a stoplight behind a big pick-up truck that is sure to send black smoke my way. So, overall, we are a bit more insulated on our roads.

But, just like Dalat, Colorado is prone to some periods of very bad air. As with COVID-19, air pollution is a global problem. The US Clean Air Act of 1970 was a piece of bipartisan legislation that aimed to control emissions and address the public health risk posed by air pollution. It’s one of the reasons you have to get the emissions on your car checked when you renew your registration (depending where you live). But The Clean Air Act will not protect us from forest fires driven by climate change induced drought. And having a law in place with clean air guidelines doesn’t mean we can keep the air clean when a booming (or not-so-booming) local oil economy in northern Colorado drives up emissions.

In the meantime, we are all breathing some bad stuff every summer day – stuff that can greatly increase your lifetime risk of cardiovascular disease and cancer – not to mention asthma and allergies. While it’s difficult (at this point) to prevent the large forest or landfill fires, we are all at risk as long as we continue burning fossil fuels.

So, like millions of other people around the world, I won’t be giving up my mask for awhile – not while the air we share is still full of stuff we shouldn’t be breathing.