#[:en]air pollution[:zh]空气污染[:]

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How’s the Air Quality in Tangshan?

There are reasons to be pessimistic about the air quality in Tangshan. Tangshan is a largely industrial city in Hebei province, which is the industrial heartland of China and one of the most polluted provinces. Tangshan also boasts one of China’s top 10 busiest ports.

    To get some hard data on this question, Smart Air analyzed PM2.5 air quality data from the Berkeley Earth Project from 2014-2018. The data revealed good news and bad news for the lungs in Tangshan.

  Tangshan’s Air Pollution: The Good News

First, the good news. The air quality in Tangshan has significantly improved over the past 5 years. Each year, PM2.5 has dropped by 10% to 20%. From 2014 to 2018, Tangshan saw an overall 46% drop in PM2.5.

    Tangshan’s Air Pollution: The Bad News

Despite 2018 being Tangshan’s best year for air quality on record, the PM2.5 still averaged 54 micrograms, which is over 5 times the WHO annual limit. That’s bad news for the lungs in Tangshan because studies have discovered that even levels around 10 micrograms affect our health.

    That also puts Tangshan much higher than major developed cities like Paris, Berlin, and London.

      Is The Improvement in Tangshan’s Air Quality A Mere Stroke of Luck?

Not quite. The Chinese government has been taking big measures to reduce air pollution, particularly in northern regions like Hebei. This finding is also in line with our earlier analysis, which found that the PM2.5 northern China have improved faster than in southern China.

  How Tangshan’s Air Varies Within A Year

Breaking down the data month by month shows that Tangshan’s pollution is lowest in the summer, dipping to an average of 50 micrograms. In the winter, PM2.5 soars to a heart-stopping 100 micrograms—10 times the WHO annual limit.

    Cities around the world show this seasonal pattern in pollution, such as in India and the US. Air pollution is worse in the winter because air tends to stick closer to the surface of the earth when it’s cold.

  Bottom line: In the past 5years, Tangshan’s PM2.5 level dropped by 46%. However, even at its best, the air pollution in Tangshan is more than 5 times the WHO annual limit.

    Protective Measures

Reducing Tangshan’s PM2.5 would bring meaningful benefits to residents’ health. Residents can take the following measures to protect themselves from air pollution:

Wear a mask outdoors when PM2.5 is above 10 micrograms (or 25 micrograms as a looser limit). Check out evidence that masks have physiological benefits here.

Use a purifier at home. Placebo-controlled studies of air purifiers have found that reducing particulate indoors prevents harm to blood pressure, inflammation, and immune response—even among young, healthy twenty-year-olds.

Smart Air is a certified B Corp committed to combating the myths big companies use to artificially inflate the price of clean air. To help people living in polluted cities like Tangshan protect themselves, Smart Air provides empirically backed, no-nonsense purifiers and masks, thereby helping to lower the cost of clean air.

    Breathe safe!

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Did Delhi's Air Pollution Drop 25% in 2019? What The Data Says

The Delhi government and Delhi Chief minister Arvind Kejriwal announced Delhi’s PM2.5 air pollution was down 25% in 2016-2018 compared to 2012-2014.

    Yet there is doubt. Thewire.in, for one, expressed skepticism about this claim.

  As data-driven nerds, we wanted to let the numbers answer this question. So we dug into the Delhi PM2.5 data to see if this claim by the Delhi government was true and to see if Delhiites are really breathing cleaner air in 2019.

  Delhi PM2.5 2015-2018

We used data available from the US Embassy to analyze Delhi’s pollution over the past 5 years. Unfortunately, the data only goes back to 2015, so we can’t test the claim back to 2012. However, there’s been no clear improvement since 2015.

  In 2017, Delhi was 2 micrograms above 2015. In 2018, Delhi was 3 micrograms lower. Thus, the data seems to be saying Delhi’s air has seen “more of the same” for the last four years.

2019: Delhi’s PM2.5 Drops 25%

Has air gotten any better in 2019? If we compare 2019 so far (January 1st, 2019 to October 1st, 2019) to the 2018 average, PM2.5 has actually dropped 25% in 2019!

    Unfortunately, this is misleading. This data is comparing the whole of 2018’s levels to just the first 9 months of 2019.

  Data shows that pollutions levels are worst during the last 3 months of every year. That’s from crop burning, people building fires for heat, and less air mixing in the winter.

  We always expect the first 9 months of any year to have lower average PM2.5, and then the last 3 months to increase that average.

Analysis of Delhi’s 2018 PM2.5 vs. 2019

However, if we compare Delhi’s PM2.5 for the first 9 months of 2018 with the first 9 months of 2019, we get a completely different answer.

When correctly adjusted for seasonality, Delhi’s 2019 PM2.5 dropped just 4% from 2018. That a paltry 3 micrograms–well within the range of random fluctuations.

  Delhi 2019 PM2.5: Bottom Line

For the first 9 months of 2019, Delhi’s PM2.5 dropped 4%. Back to 2015, Delhi’s PM2.5 is mostly flat. Thus, Delhi’s air has seen little improvement over the last four years.

Either way, Delhi’s air pollution levels are still dangerously high. The 2019 average of 80µg/m3 so far is 8 times higher than the WHO’s annual limit.

  Open Data

To help people get an idea of how Delhi’s PM2.5 has changed over the past 5 years, we’ve created a year by year and month by month table, breaking down the data. Data is openly available from the US Embassy in Delhi.

  Note: In the main analysis, we seasonally adjusted 2015 data to account for the fact that January data is unavailable.

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Can air purifiers kill dust mites?

Dust mites look scary.

  And apparently they’re probably in my home, since they’re in most people’s homes. A survey found dust mites in 84% of US beds and 68% of European beds.

  Yet it’s hard to know for sure whether they’re in our homes or not because they’re mostly too small to see with our eyes. The more I write, the more OCD I’m becoming.

  Will  Air Purifiers Kill Dust Mites?

I should say I’m NOT an expert in air pollution. I’m just a dedicated data nerd who was doing psychology research in Beijing and then got (kind of) forced into building DIY air purifiers to fight the crippling air pollution I was breathing.

  During that process, I started testing air purifiers with HEPA filters—these guys.

  Most air purifiers use HEPA filters, so let’s start there.

  These fiber filters capture over 99% of particles 0.3 microns and above. That’s good news for my probably-dust-mite-infested home because dust mites are 200 to 300 microns long.

  That’s easily in the range that HEPAs capture. Now, I’m not sure if getting stuck in a filter would kill a dust mite. They die in environments with low humidity, and getting constantly blown by air might do the job, but that’s speculation.

  Bottom line: Most air purifiers will capture dust mites, but may not kill them.

  Wait, Dust Mites Need to Be in The Air

Hang on, dust mites need to be in the air for an air purifier to capture them. The problem is they live in carpet, bedding, and upholstered furniture, so they’re not usually floating in the air.

  It turns out dust mites do get thrown into the air. When we walk on carpeting, sweep the floor, dust our homes, and change our bed sheets, dust mites get thrown into the air. And because they’re so small, they stay suspended in the air for 20 minutes to 2 hours.

  That means purifiers can capture dust mites if you have the purifier on while dusting, changing sheets, or even walking around. If you’re try to target dust mites, you might want to scuff your feet along the floor.

  Dust Mites Create Even Smaller Allergens

But the picture gets more complicated for people with allergies. Dust mites create allergens by ejecting poop particles and “partially digested enzyme-covered dust particles.” In other words, their waste is smaller than their bodies.

  These particles are as small as 1 micron or even 0.1 microns.

We’re in trouble now, because HEPA filters capture particles 0.3 and above (according to websites like this one).

Fortunately for us air-breathers, this is a common misconception. This misconception would lead people to conclude that HEPA filters DON’T capture dust mites.

  You’ll see purifier companies use this myth to try to justify when you need their “proprietary technology” instead, like Molekule does.

  A glance at the Wikipedia page for HEPA filters (or the data I share in this answer) reveals that HEPA filters capture lots of particles below 0.3 microns.

  Heck, even pollution masks like this one I’m wearing capture tiny 0.007 micron particles (1).

  Bottom line: HEPA filters will capture dust mites and the smaller dust mite allergen particles they create.

  View the original article on Quora here.

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Is Beijing or Delhi air worse?

Beijing and Delhi often make headlines for air polluted cities, but which city has worse air? I wanted to get some hard numbers on how the two cities’ air quality compare.

  The Data

To do that, I analyzed PM2.5 data from the US Embassies in Delhi and government monitors in Beijing from 2015 to 2018. The data shows that both cities routinely face PM2.5 levels that are 10 times the World Health Organization annual limit. But besides having unsafe air, the data told two different stories.

    Beijing PM2.5: A Redemption Story

Over the past 3 years, Beijing’s air pollution levels have dropped by an impressive 40%, from 80 micrograms to 48 micrograms. This is likely due to the Chinese government’s efforts to reduce air pollution. It also fits with our analysis of municipal Beijing air quality data, which found decreasing PM2.5 across China.

However, Beijing air is by no means healthy. Even though 2018 was Beijing’s cleanest year on record, Beijingers still breathe an average of almost 5 times the WHO annual limit.

  Delhi PM2.5: A Horror Story

Comparing the two cities gives a picture of two different trajectories. While Beijing has improved, significantlyDelhi has seen little improvement in its air quality.

Since 2015, Delhi’s PM2.5 dropped 3% – essentially no change. In 2018, Delhi averaged 105 micrograms, which is more than double Beijing.

  Why Is Delhi So Much More Polluted than Beijing?

Breaking the data down month by month, it becomes clear that Beijing and Delhi both have low (but still unsafe) air pollution in the summer. The winter is when the differences magnify. From November to January, Delhi’s PM2.5 skyrocket to an average of around 200 micrograms. That’s 20 times the WHO annual limit!

    Why is Delhi’s air pollution bad in the winter? The winter brings crop burning, along with coal used for heating. Winter also brings air inversions, which trap layers of air close to the city, along with all those pollutants.

      Is Delhi or Beijing Safer?

Based on what scientific studies show about the health effects of air pollution, neither city is safe. Both cities are far above the WHO annual limit of 10 micrograms. What’s more, the more studies I read, the more I’m convinced that there’s no safe level of PM2.5. For example, scientists used statistics to estimate how many people die each year from air pollution at different levels of PM2.5.

      The red line shows how many people die each year when PM2.5 averages different levels in a city. Now here’s where 2018—Beijing’s best year on record—falls on that graph.

    If all of China had air like Beijing’s best year on record, the pollution would cause an astounding 390,000 deaths every year. Thus, even though Beijing has made great progress, the air is still killing people.

  Bottom line: Both Beijing and Delhi average unsafe levels of air pollution year-round. Beijing air is unhealthy at 48 micrograms, and Delhi air is even more unhealthy at 105 micrograms.

  Protective Measures

Here’s how you can protect yourself from air pollution:

Wear a mask outdoors when PM2.5 is above 10 micrograms (or 25 micrograms as a looser limit). Check out evidence that masks have physiological benefits here.

Use a purifier at home. Placebo-controlled studies of air purifiers have found that reducing particulate indoors prevents harm to blood pressure, inflammation, and immune response—even among young, healthy twenty-year-olds.

Smart Air is a certified B Corp committed to combating the myths big companies use to artificially inflate the price of clean air. To help people living in polluted cities in China and India protect themselves, Smart Air provides empirically backed, no-nonsense purifiers and masks, thereby lowering the cost of clean air.

    Breathe safe!

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Fast-Growing India Startup Zomato Installs Smart Air Ladakh Air Purifiers

Helping to fight air pollution in Gurgaon, one of India’s most polluted cities, Smart Air installed 91 Ladakh purifiers in the offices of India’s biggest food delivery startup: Zomato.

  In December 2018, Zomato was moving into their new 100,000 square foot office in Gurgaon, just outside New Delhi. Zomato needed a clean air solution for their team to combat the detrimental effects of air pollution on their staff. Recent painting, new carpets, and remodeling work meant the Zomato team was facing problems with volatile organic compounds (VOCs) like formaldehyde and benzene. Along with Delhi’s and Gurgaon’s persistently high PM2.5 levels, Zomato needed to solve the serious indoor air pollution issues in order drowsiness and headaches for their team.

Zomato’s Clean Air Solution in Gurgaon

To kit out the entire office space with clean air, Smart Air installed 91 Ladakh and Ladakh Mini air purifiers. The Ladakh units are powerful, quiet standalone air purifiers that provide huge amounts of clean air for a cost-effective price. All this whilst operating at whisper-quiet noise levels. Put another way: a single Ladakh puts out more than 3 times the clean air as a fancy Swiss-imported IQ Air—at less than 10% the cost.

The Ladakh puts out more clean air at a fraction of the price of the European Imports

Smart Air’s Simple, Effective ‘Plug and Play’ Purifiers Eliminate Lengthy Lead Times

Zomato had a tight timeline to move into their Gurgaon office. Air quality levels in Gurgaon were scarily high, and they wanted to move their staff into space with clean air as soon as possible. To provide an effective and reliable solution to Zomato, Smart Air came up with a plan that would realize Zomato’s goals, all without requiring a single change to the office building’s infrastructure. The Ladakhs are simple, reliable and easy to use standalone air purifiers that can be installed in your office without the need for lengthy lead times.

  With the Ladakh air purifiers, we managed to get Zomato clean air in a matter of weeks, drastically quicker than the months required for custom clean air solutions like HVAC and centralized air system modifications. What’s more, the fact that Zomato needed no change to their building infrastructure meant they also saved huge amounts of money during the installation. It was win-win for Zomato.

Smart Air Ladakh providing clean air at Zomato’s Gurgaon office

How Smart Air Was Able to Solve Zomato’s Air Quality Problems: the Data

As part of Smart Air’s air quality service, we provided routine audits of the air quality (including PM2.5, AQI, formaldehyde and VOC readings) to Zomato at their Gurgaon office. We ran 6 audits at the Zomato workspace over the course of 21 days to measure and evaluate the effectiveness of this clean air solution.

The data was conclusive: in just 21 days, the Ladakh air purifier solution brought down PM2.5 by 87%, formaldehyde by 82%, and VOCs by 93% on average across the entire Gurgaon office space

Why Zomato Chose Smart Air

As one of India’s fastest-growing startups, why would Zomato choose to work with Smart Air? The answer is simple: Smart Air focuses on providing effective, simple solutions that provide the best solution at the lowest cost. By partnering with Smart Air, Zomato knew that they could get clean air into their Gurgaon offices, protect their staff and monitor their air quality, all whilst costing less, and operate more effectively, and with a quicker installation than other solutions.

Air purifier technology is simple—fans and HEPA filters. Zomato knows this, so that’s why they chose Smart Air.

How Can You Bring Clean Air to Your Lungs?

Smart Air believes that, if most people saw the data behind purifiers, they wouldn’t pay hundreds of thousands of rupees for clean air. By focusing on that simple science, Smart Air makes simple, effective purifiers without the marketing noise of traditional companies. If you need clean air in your office, school or hospital contact the Smart Air team to bring Ladakh to your lungs.

 Call us now for clean air: 95990 97907

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So You Thought Hong Kong’s Pollution Comes From the Mainland? – Supplemental Data

This article includes supplemental data for the main article “So You Thought Hong Kong’s Pollution Comes From the Mainland?”

This supplemental data will show how high and low wind speeds affect the PM2.5 levels and hence Hong Kong’s pollution. Ultimately, this supplemental article draws the same conclusion as the main article.

  Does Wind Speed Affect PM2.5?

What if particulate matter can only be transported at high speeds? In order to test if wind speed affects PM2.5, I repeated the analysis for PM2.5 data at wind speeds below average and above average.

The data shows that lower wind speeds in Hong Kong almost always correlated with lower PM2.5 levels, regardless of the wind direction.

However, this also shows that air pollution was significant even without strong winds blowing PM2.5 from Mainland China. This means that there are PM2.5 sources within Hong Kong as well.

When wind was blowing at higher speeds from the direction of Mainland China, the PM2.5 level was about 20% higher than average.

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So You Thought Hong Kong’s Pollution Comes from Mainland China?

Air pollution is a serious problem in Hong Kong, and Hong Kongers often complain that the worst of it comes from Mainland China. Is that fact or a convenient scapegoat? After all, Hong Kong is a densely populated developed city with one of the busiest ports in the World – it is likely that they have their own sources of pollution. I set out to find data on where exactly Hong Kong’s air pollution comes from.

  How Much of Hong Kong’s Pollution Is Local?

One way to answer this question is see what happens to Hong Kong’s air pollution when the wind blows from the Mainland. To do that, I analyzed data on Hong Kong’s PM2.5 and wind direction and speed from 2016 to 2018.

  Where Hong Kong’s Pollution Comes From

Anytime the wind blows from the West-North-West to East-North-East (the arrows below), Hong Kong’s air is coming from Mainland China. If most of Hong Kong’s air pollution is coming from China, we should see air pollution spikes whenever the wind comes from that direction.

  Does Wind Direction Affect PM2.5?

When the wind was blowing from directions not from Mainland China, the average PM2.5 level was 25 micrograms. In contrast, when the wind was blowing from Mainland China, the PM2.5 level was 29 micrograms, which is a 15% increase.

This data gives two (somewhat contradictory) takeaways:

Yes, Hong Kong’s air pollution is 15% worse when the wind blows from the Mainland.

However, even when no air is coming from the Mainland, Hong Kong still averages more than twice the WHO annual limit of 10 micrograms.

Thus, even without the influence of the Mainland, Hong Kong still has significant sources of air pollution from within.

  Does Wind Speed Affect PM2.5?

When there was no wind, the PM2.5 level averaged 24 micrograms. This is a few times over the WHO’s annual limit of 10 micrograms. This proves that even without external influence, Hong Kong’s pollution is still significant.

I repeated the analysis of PM2.5 level at low and high wind speeds and came up with the same conclusion (see details here).

  Bottomline: Wind direction and speed marginally affect air pollution in Hong Kong. When wind blows from Mainland China, PM2.5 levels in Hong Kong increases 10 – 20%. However, the main sources of air pollution still come from within the city. Hong Kong should take measures to reduce their own sources of air pollution.

  Caveat: This data is for particulate pollution. Particulate “affects more people than any other pollutants,” but there are also gas pollutants like ozone and NO2. According to this data, Hong Kong also has unsafe levels of NO2, SO2, and ozone.

  If I were in Hong Kong, I would protect myself from air pollution by following these measures.

Breathe safe, Hong Kong!

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How's the Air in London? See the Data

Over 100 years after “London Fog,” is London’s air safe? I just analyzed data on London’s PM2.5 pollution—tiny particles in the air. In 2018, London averaged 12 micrograms of PM2.5.

  What Does That Mean?

Based on this data from the King’s College London, London’s air quality is slightly above the WHO annual limit. That limit is important because research shows that even levels around 10 micrograms affect our health.

However, 12 micrograms is already pretty good; it’s just within the ‘Healthy’ range for the US air quality index. And it comes after years of improvement, according to separate World Bank Data.

London’s PM2.5 is lower than other major cities like Paris and Berlin, although there are safer major cities, such as Montreal.

  But compared to the cities around the world that are famous for pollution, like Delhi or Beijing, London isn’t even close!

    Monthly Analysis

However, one problem with the data above is that it averages over the entire year. When we do a month-by-month analysis, we can see that London’s air is in the ‘Moderate’ range about half the time.

    Bottom line: London’s PM2.5 is not the worst in the world but averages slightly above the WHO annual limit.

Caveat: I analyzed PM2.5 data. This covers particles in the air, but it doesn’t cover gas pollutants like NO2. That’s important for London because studies have found unhealthy NO2 levels in London and around England.

  How to Protect Yourself

Despite London’s relatively good air quality, measures can still be taken to protect against air pollution. Studies have found that wearing a mask outdoors during bad air pollution prevents harmful effects on blood pressure and heart rate variability. Even at very low levels of air pollution, a study in the US found that using air purifiers to reduce indoor PM2.5 from 11 micrograms to 7 micrograms significantly improved blood pressure.

Breathe safe, London!

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How do people in Beijing exercise with such bad air pollution?

I’m in Beijing right now, and I’m going to exercise today. So what can I do when the world outside my window looks like this? Would exercise do more harm than good?

  1. The point where exercise becomes harmful

Researchers at Cambridge analyzed studies on the benefits of exercise and the harms of air pollution and tried to calculate how bad the air has to be for exercise to be harmful. There are lots of different types of pollution, but they focused on particle pollution (PM2.5), which the WHO says kills more people than any other pollutant. They used biking outdoors as the form of exercise—something I’ve experienced in Delhi.

    Here’s the cost-benefit analysis in a city with 50 micrograms/m3 of PM2.5 pollution. That’s about the average level in Shanghai. For comparison, the WHO annual limit is 10 micrograms.

    First check out the green circle, the tipping point. Biking outside is beneficial to lifespan (in other words, “not dying”) up to about 70 minutes.

Then check out the red circle, the breakeven point.

    At about 300 minutes it actually starts to become harmful. But at that point you’ve been biking for almost five hours, so you need a break anyway.

Is exercise as good as pollution is bad?

Let’s say you do both. You exercise, but you breathe polluted air. How do those balance out? Are you back to the starting point?

For a sense of scale, I got statistics on the danger of different behaviors from this recent epidemiological study. They don’t have exercise, so I compared eating unhealthy foods. Here’s the years of life lost from PM2.5 versus eating unhealthy foods.

    The effect of eating a bad diet is worse than air pollution. My guess is exercise is at least as potent as air pollution, if not stronger. That’s why exercise is still helpful in a polluted city.

But what about really bad days and really bad cities?

Hey, 50 micrograms, that’s child’s play!

    Places like Beijing and Delhi have real man air. The World Health Organization found Delhi’s PM2.5 averages 153 micrograms. Beijing easily has days that bad. So how does the calculus change then?

Here’s a slightly different graph with the tipping point (red) and break-even point (blue). I drew a line for Delhi’s average PM2.5. In Delhi, biking starts to be harmful at just 30 minutes (the breakeven point).

  The line for the tipping point doesn’t even extend up to Delhi’s PM2.5 levels, so we don’t know at what point it loses its beneficial effect. I tried extending the line up and came up with, maybe 2 minutes?

    And keep in mind, this is only considering PM2.5 pollution. It does not take into account any gas pollutants like ozone or NO2. So the total effect of all air pollutants would be worse.

Bottom line: This estimate suggests outdoor exercise on bad air days or particularly bad cities becomes harmful after just a few minutes.

But, but…

Keep in mind this is an estimate. It is based on epidemiology research, but it uses lots of assumptions. There are lots of factors that could change the equation:

If you’re overweight, the benefit of exercise would probably be much higher.

If your body reacts strongly to air pollution, the harm probably starts earlier for you.

This estimate is only for death. It doesn’t calculate in not-fun, but not-death problems like lung function and asthma.

If all that sounds like a lot of assumptions and uncertainty, here are two ways to change that equation.

2. How I’m getting my exercise today in Beijing.

Method 1: When I’m in Beijing, I solve this problem by wearing a mask.

    These simple masks are as cheap as 50 cents, and scientific studies conclusively show they reduce particle exposure by well over 90% (I run through the evidence here). Solid random-assignment studies have also found that wearing masks just like these prevent effects on blood pressure and heart rate variability (I explain those studies here).

I’ve fit-tested these masks on my very own face and found these masks easily score over 90%.

    Here are results from several masks on my face and my colleague’s face:

    So when I’m in Beijing and Delhi, I bike around all day getting good cardio exercise while breathing less particulate than people sitting indoors. And I don’t need to mess around with cost-benefit models!

    Method 2: I work out indoors.

Here’s a trick: Simply by being indoors, you’re breathing less particulate pollution.

I tested air indoors and outdoors in Beijing and Shanghai (including at my gym!). The data showed that particulate levels indoors are only about 60% of outdoor levels, even in places that don’t use purifiers.

    My results are almost identical to the US EPA’s much more rigorous tests.

Just make sure that the doors and windows are closed! The effect basically goes away in places with the windows open.

    And if you want to limit exposure even further, you can workout at home with a purifier on.

Bottom line: Exercising indoors will reduce particulate exposure.

That’s how I manage to exercise and stay healthy while still getting to explore amazing cities like Beijing and Delhi.

  Breathe safe!

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Is the Molekule air purifier really better than those already on the market? Review

Over this last Christmas, I was at home on the couch, and my dad asked me if I’ve seen this new Molekule air purifier he saw an ad review for.

    He asked not because he’s interested in purifiers, not because I’m some PhD in fluid mechanics (I’m a cultural psychologist, not a physicist), but because I’ve been building and testing DIY air purifiers ever since a Beijing airpocalypse in 2013 had me coughing for weeks.

Here’s one of the more “beautiful” machines I built and tested:

    Why would a psychologist spend four years building and testing purifiers? Because the air outside my Beijing apartment was “beyond index”…

    …and the view in my online shopping cart looked like this.

    I was scared, and these companies were saying that clean air costs $500 or $1,000. Soon I found I could make my own purifier for about $30 (see the full data on how it effectively reduced even tiny PM2.5 particles in my room!)

  The lesson I’ve been learning throughout my testing is that big purifier companies actually love smoke. That smoke comes in the form of claims that we need filters imported from Switzerland (learn more about that ‘fancy’ Swiss company I’m talking about here), not because they’re high profit margin, but because the technology is better.

    That’s the backdrop that was in my mind as my dad handed me his iPad, and I clicked on the Molekule air purifier ad. So let me review the claims:

  Molekule Air Purifier Claim #1

Immediately, I saw this claim.

    These guys are so technologically advanced they haven’t read the Wikipedia page about HEPA filters. If they had, they would’ve learned that HEPA filters are actually fantastic at capturing particles under 0.3 microns.

    See, the problem is our intuition is to think of HEPA filters like a net. If a particle is smaller than the holes in the net, it gets through. So the smaller the particle, the harder it is to capture. Makes sense.

    That logic works for objects as big as marbles. But when we get to really small particles—like particles under 0.3 microns—things start getting weird. Particles that small have so little mass that they actually get bounced around like a pinball when they hit gas molecules (known as Brownian Motion). So they move in random zigzag patterns.

    Why that matters is that tiny particles are small enough to fit through HEPA filters—if they flew straight. But because they fly in zigzag patterns, they end up hitting the fibers and getting stuck.

OK, that’s a lot of theoretical explanation. Is there any test evidence for this? There’s lots! One test I like is this thesis on duct filters (never thought I’d say that about a thesis on duct filters).

  That’s the percentage of particles the filters captured at different sizes. See how the effectiveness goes down, but then starts to go up again? That’s below 0.3 microns—the particles Molekule claims that regular purifiers can’t get.

By the way, this study was on furnace filters, which are lower grade than HEPA filters. But the principle works for any fiber filter. It works for the HEPA filters that are in purifiers (see this guy’s tests down to .01 microns) and even masks (I describe mask tests down to .007 microns here). That means you don’t even need a fancy HEPA filter for Brownian motion to work its magic.

So why is Molekule claiming HEPA filters can’t capture any particles below 0.3 microns?

  Either they don’t know this basic fact about purifiers (in which case, I’m highly skeptical of their claims of being experts), or they’re straight up lying about purifiers to sell you a more expensive one (in which case, I don’t trust them).

Bottom line: Their claim to superiority about particle sizes is false.

  Molekule Air Purifier Claim #2

Their second big claim is about bacteria. They claim that bacteria will grow on regular HEPA filters and then get released back into the air, so you need their Molekule technology to kill that bacteria.

I’ve used HEPA filters in my Chinese apartments for years. I’ve also shipped 40,000 of these low-cost DIY purifiers to people all over China and India through my social enterprise Smart Air.

    That includes lots of people in hot and humid Shanghai and Shenzhen, not to mention basically all of India (which qualifies as hot and mostly humid). I’ve never once seen or heard of mold or bacteria growing on these HEPA filters. That’s despite the fact that I had a mold problem in my Beijing apartment before I started using purifiers.

Bottom line: Is it theoretically possible for bacteria to grow on a HEPA? I suppose so. But even in these extreme environments, I’ve seen absolutely zero evidence that it actually happens. If it were a problem, I don’t see why airplanes and hospitals use HEPA filters to trap bacteria.

  Molekule Air Purifier Claim #3

Molekule says HEPA filters can’t capture viruses because they’re too small. But the Molekule air purifier can!

  This gets back to point #1. HEPA filters (and really most filters) are great at capturing viruses.

    Viruses are solidly in the range of very, very high efficiency for HEPA filters and even masks.

    Molekule Air Purifier Claim #4

About allergens, Molekule says HEPA filters “only traps larger allergens” and then releases them back into the air anyway.

    We’ve seen the claim about small particles before, so we know that’s wrong. But what about releasing them back into the air?

I’ve seen people worry about this, but I’ve never seen any evidence for it. And in the tests I’ve done, all I find is evidence of the opposite. Let’s take this 200-day test longevity test. See, I wanted to know how long a HEPA filter would last on my DIY in real Beijing air. So my Smart Air co-founder Gus tested it everyday in his Beijing bedroom for 200 days.

Here’s what a regular test day looked like. There’s particulate in Gus’s bedroom (red line) and outside (blue line).

    Here are 10-day averages all the way out to 200 days (all original data available here).

    Even out to day 200, the HEPA filter was managing 50% reductions in room particulate. At no point was the HEPA filter making room air worse.

That’s just not how filters work. They capture particles. They don’t release them. Unless you’re shaking them or cutting them open, they’re not going to release those particles back into the air.

  Molekule Air Purifier Claim #5

There is one claim that strikes me as “could be true.” It’s their claim that the machine “destroys” chemical gases known as volatile organic compounds (VOCs). That includes stuff like formaldehyde and toluene, which come out of products that we buy, like carpeting.

    They’re right that HEPA filters don’t capture gas pollutants. HEPAs are for particles, not gases. They’re weirdly claiming that carbon is only effective for 80 minutes. That must be an incredibly tiny carbon filter. It doesn’t match my tests with the carbon filters on regular purifiers.

But does their machine actually “destroy” VOCs? Maybe it does! If so, that would be the only actual selling point of this machine. Unfortunately, they don’t explain what the filter is (beyond using fancy-sound terms like “nano”), and they don’t provide any data with enough detail that I could assess it.

Bottom line: The Molekule might be better at capturing VOCs, but they do not provide convincing evidence for it. The other information on their site is so bad that it makes me skeptical of this claim.

  So what’s an air breather to do?

I’ve been nerding out on purifiers ever since that 2013 Beijing airpocalypse. If I can sum up all of my testing into one message, it’d be this:

Air purifiers are shockingly simple. They’re a fan and a filter. Cheaper purifiers perform just as well—and often outperform—the ridiculously expensive machines.

So brush aside marketing claims, beautiful Nordic families living in all-white homes, and keep your money.

    Instead, check out any one of several sources of independent purifier tests and choose the best combination of effectiveness and price. I outline several sources of tests here:

What is the best air purifier on the market today?

Breathe safe!

P.S. I’ve ranted for too long about Molekule’s claims, but please indulge me the claim at the top of their homepage.

    Finally a purifier “that actually works.” Click on the link above to see dozens of purifiers that cost far less and “actually work.”

  View the original article on Quora here.

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