Although we’ve certainly done multiple articles on this before, second reader question on “how do I control my indoor air quality” means it’s time for another blog post on air quality technology.
I live in San Fransisco where the air is not particularly good. How do I protect my newborn baby? I’m worried both about dust from cars and blowing over from China as well as chemical emissions from our new rugs and paint.
I’ve come down with allergies. Taking control of my indoor air quality now sounds very appealing.
Automobile exhaust probably responsible for some “allergies”
Kudos to you for trying to take control. Funny thing about allergies: we’re getting anecdotal evidence from family and friends that all of this technology is somewhat new to the medical community as well (at least the concept that it so affordable anyone can just go out and buy it). We have friends and relatives that for years were diagnosed with minor “allergies” that everyone (including the doctors) assumed were minor pollen allergies. The standard treatment, for years, was to prescribe Benadryl or the latest allergy inhaler, and sort of a “take two of these and call me in morning.” Allergy tests are expensive. (As most antigens are proteins, it is not even clear if automobile exhaust — the long chain hydrocarbons known as soot that make up much of the PM2.5 dust pollution in cities that we’re talking about here — is even presented as antigen. Maybe time to send an inquiry over to our friends in the immunology departments back in the Northeast.)
After sending over our app and dust sensor, it became pretty clear that the “allergies” mainly acted up when PM2.5 was high. Although pollen is PM2.5, it’s not year round the way automobile exhaust is. Different pollen antigens are high on different high pollen days, whereas automobile exhaust is more constant. Also, high pollen counts don’t imply high PM2.5. Most days in the winter (when these “pollen allergies” are acting up) also don’t see a lot of pollen. Since our friend’s “allergic reactions” where highly correlated with high EPA PM2.5 days, it seems (anecdotally) her allergy is due to cars and not pollen.
Of course, saying someone is allergic to PM2.5 automobile exhaust is a little like saying someone is allergic to hydrogen cyanide. It may be technically correct (they are more sensitive than most people, and the primary reason for that sensitivity is due to an immune response. But they’re both poisons. PM2.5 at high enough levels (but not entirely common in large cities) is correlated with increased incidence of cancer. Nasa estimates PM2.5 dust pollution kills 2.1 million annually.
All of this being said, this isn’t intended as medical advice. If you’re suffering from allergies, please see a competent medical professional such as a doctor. In particular, our app (currently free) is intended mainly by healthy people to monitor and reduce dust build-up in the home. (We’ve kind of been reluctantly dragged into the whole cancer and allergy thing after convincing ourselves it was real.) The current terms of service prohibit it being used in any kind of sensitive applications, which would anything medical. If you think you’re ill, sensitive to dust, or suffering from allergies, please consult your doctor about alternatives first.
Caution about “too clean” environments for newborns
That’s point one. Point two is on the newborns. For newborns there have been several recent studies (such as this one) that suggest exposing newborns to certain kinds of dust and pet antigens during the first year of life helps prevent asthma. (Unfortunately, after the first year of life, exposure apparently increases incidence of asthma allergies. Also, the dust antigens in these research articles tend to be natural ones: pets, dust mites, bug droppings. Nothing in this research suggesting exposing your newborn to automobile exhaust is a good idea, ever, although that’s where much of the PM2.5 in urban environments comes from.)
There’s some discussion about developing a spray that would contain dust mite and pet antigens that you could spray around a newborn’s crib. That way the newborn (in the first year of life) would be exposed to antigens, whereas everyone else (much older than the first year, and therefore not wanting to be exposed to these things) would not be exposed, or would be less exposed. Also, you could expose the newborn to these natural dust antigens while still running your air purifier to filter out the automobile exhaust that is presumably less healthy. Unfortunately, the spray just described does not yet exist. What may exist soon, however, is a vaccine against dust mite antigens. (Also, unlike the spray technology, the aforementioned dog technology does already exist. In fact, it’s existed for 30,000 years. So you have the dog run around releasing dust antigens into the environment around your newborn while you use the air purifier to filter out automobile exhaust.)
Newborn health and allergies are complex issues. There is often conflicting information on what causes and prevent allergies. Not all studies are so sure having pets around is helpful against allergies Some studies think it may make the problem worse, and even the study we cited cautions these antigens may be more harmful than helpful after the child’s first year. These are some good points to discuss with your doctor before embarking on heavy air filtration (or pet traffic) around a newborn in it’s first year.
VOCs and chemical emissions
One of readings asked about chemical emissions from things like paint, plastics, and carpets. These are VOC emissions, not PM2.5 dust pollution. People confuse them with PM2.5, and assume the same sensors and techniques will work to control both. Part of this confusion stems from air purifier manufacturers gladly promising on their cartoons to deal with both. (Probably because every manufacturer does this, so to say anything else would forfeit sales to a competitor.) The reality is that these are very different types of pollution requiring very different techniques to control. At a minimum, you’d need two sensors, so that you’d be aware of both. That way you, or an intelligent home automation system or app, could select the best strategy based on the current environment.
We talk a lot in this blog about controlling dust (or PM2.5/PM10) emissions. That’s something you can control with an inexpensive air purifier (or, worst case scenario, you can wear a respirator or fashionable plague bird mask. They’re actually handing these out in some Chinese cities.) There’s also plenty of non-health reasons you’d want to cut down on PM2.5 in your home: less need to vacuum and less equipment failure due to dust getting into your computer mouse. (The World Bank estimated that non-health costs from excessive PM2.5 pollution creating problems like premature equipment failure and even roadside accidents was unmeasurable but in the billions if not trillions of dollars annually. It’s a very serious problem, but most people assume either their air is clean, their air purifier is magically making the air completely clean, or that nothing further can be done about the problem.)
VOC (Volatile Organic Compounds) are another type of pollution. Bad odors are one type of VOC, usually a harmless form. Things like emissions from rugs, plastics, and paints are another kind. Your air purifier manufacturer may be magically promising to remove VOCs from your home through a tiny charcoal filter (or even 19 pounds of zeolite in one — heavy — purifier model). Unfortunately, if these air purifiers absorb the VOCs in your home, they’re just as likely to slowly re-emit the VOCs later again. For this reason, we’re with Consumer Reports (CR) in being suspicious of air purifier claims of removing VOCs. If you suspect VOCs are a problem in your home, we agree with CR that you’re probably better off increasing the ventilation in your home rather than relying on an air purifier.
At least that was good advice before VOC sensors became readily available. Now a days you buy devices (well, at least hobbyist kits) that can measure the VOC level in your home and compare it to outdoors. (In our office in Los Angeles, the VOC level tends to be lower indoors than outdoors, so ventilation doesn’t make sense. The VOC levels are already as good as we can easily get them. Your home may be different, which is why a VOC sensor may be a good idea.
Probably the most readily available VOC sensor kit in the U.S. is the Air Quality Egg tricked out with a VOC sensor from Wicked Devices. While you’re adding add-ons like the VOC sensor, you might as well also add the PM2.5 dust sensor add-on they offer. (Our app supports this, together with the Dylos sensor.) The AQE is unfortunately just a hobbyist kit, not a “consumer ready product”, and it shows. The dust readings were not anywhere nearly as reliable in our tests as was the Dylos unit (the other dust sensor our app supports).
Unfortunately, the idea that these pollution sensors are extremely inexpensive and that anyone can afford one is a new one. As a result, the AQE is one of the few games (or perhaps only game) in town at the moment if you want to measure VOC levels in your home. This will change.
Finally: air purifiers with built in sensors. If only they worked.
One last note about VOCs: One of the more award winning air purifiers out there are the Whirlpool models. They’re quiet, efficient, and relatively economical. We’ve recommended them in the past.
If you look on Amazon, their latest unit is advertising a “sensor.” (We’ve previously discussed their award-winning older model without the sensor.) Their marketing on this is confusing; in multiple places it only mentions a VOC sensor, although at one point it mentions “dust sensor that works with VOC-SENSE.” From our interpretation of the marketing blurb on Amazon, there is only a VOC sensor, not both a VOC and dust sensor. (In one of the earlier Q&A posts, a reader on Amazon suggested the VOC sensor can detect pollen. This is also wrong. Pollen is PM2.5, it cannot be detected by a VOC sensor. It seems a lot of people are confused and think dust and VOCs are the same thing.) While it would make sense to include both a dust and VOC sensor, if both were included the marketing blurb would emphasize dust consistently in relation to the auto fan setting, and the feature would be called something other than “VOCSENSE” which implies the ability to sense only VOCs.
It looks like Whirpool has decided their consumer base are smokers, at least for this model. Cigarette smoke is one of the few pollutants for which VOC and PM2.5 dust levels are correlated. So, if you smoke, the VOC sensor will speed up the fan, and the air purifier will remove more PM2.5 (which is what it’s much better at than removing VOCs). It will also speed up due to odors. But, as we discussed above (and Consumer Reports also discusses), these air purifiers are much better at removing PM2.5 than they are at removing VOCs. So it seem’s it’s the wrong sensor.
In general, we like the idea of the air purifier having it’s own sensor and on-board intelligence. The Coway smart air purifier is one of the few that does indeed include an on-board PM2.5 dust sensor to control its fan. (This is a sleek, quiet, compact unit that is smaller than the Whirpool units we described. In exchange for that smaller design, it also filters a lower volume of air.)
Unfortunately, that dust sensor is much more flakey than the Dylos, at least in our test. (It sometimes seemed to speed up in response to increased dust as measured by the Dylos. At other times it seem to respond to air currents or sped up or slowed down for no explicable reason.) A feature we’d really like to see in the Coway is home automation integration like ZigBee where it could report its dust sensor readings to a smartphone app (maybe like ours) and let you control the level of dust you’d like to reach (or at least tell you want it was reading and what level it’s programmed to target). Another issue with the Coway for home automation purposes is that the electronic controls will lose their setting if power is lost. The means you can’t control the Coway through a home-automation smart outlet (and the Coway itself, of course, doesn’t work with home automation systems.) Then again, Coway should be commended for being one of the few (or perhaps only) air purifier that has the correct sensor (PM2.5) built into the unit.
We’re still hoping future air purifiers allow themselves to be controlled via home automations standard (e.g., Zigbee) and also report their sensor readings back to users somehow (ideally via home automation protocol for app control). With both the Whirlpool and Coway smart models described above, we’re not sure exactly what their reading (dust, VOC, or something else). And, unless the air purifier reports the air quality back to you in numeric terms, you can’t know the purifiers are actually working. This brings us to our next section: sensing the air yourself, which has become very affordable.
Air Quality Tech
For sensing your home PM2.5 quality levels, we recommend the Dylos DC1100 or the previously mentioned Air Quality Egg with Dust Sensor, both of which are supported by our app. We recommend the former over the latter (unless you already buying the latter to measure VOCs) as it produces much higher quality readings (at least in our test).
Our app supports both Pro and less expensive Non-Pro version of the Dylos. The Pro is 3x more sensitive, and (getting technical here) the cut-offs between the two channels more closely align with PM2.5 (the cutoff is at 2.5 micros for the Pro), so comparing the numbers in our app with outdoor EPA PM2.5 numbers will be more accurate with the Pro version. It may be a little easier to convince yourself our app works if you get the Pro version. That said, our app supports both versions, and the conversion from the non-Pro may be good enough for most folks, so you may be able to save yourself some money with the non-Pro version.
There’s plenty of further information about clean home tech in older articles on this blog.
Legal disclaimer: Again, not intended as medical advice. Consult a doctor if you are ill or believe you have allergies. See our Terms of Service for full disclaimers.
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