Whole house air filtration to reduce pollutants including pollen, dust, exhaust fumes

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timmmay

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#262272 14-Jan-2020 08:51

Background

I've been seeing more stories recently about air quality, such as this one from NY Times and another from Vox. The Vox article noted that air filtration in schools consistently increased kids test scores - 0.2 standard deviations, which isn't huge, but was consistent. I have a toddler at home, so would be good to make sure he's breathing good quality air.

We live near a motorway, with the intake for our ventilation system maybe 15 meters from the motorway. The motorway is down a hill a bit so in a bit of a gully that would blow some of the fumes away, behind some trees, so you can't actually smell anything, but I suspect we have more exposure to exhaust than most people. NZTA has a page on pollutants that includes the following

Which air pollutants are of concern?

Transport-related air pollution is of concern because many of the pollutants that are released are known to cause adverse health effects. Although there are a wide range of pollutants in the emissions, most of the health effects result from the following key indicator pollutants listed below. These pollutants are assessed against national standards, targets and guidelines:

nitrogen dioxide (NO2)
small particulate matter (PM10 and PM2.5, ie, less than 10 and 2.5 micrometres, respectively).

Filter Choice

We currently have a Simx G4 filter on our ventilation system, which should filter out particles >= 5um according to this source, or >= 10um according to this source. Given the filter is due for replacement soon I'm considering putting in a better filter system. I'm interested in opinions (and solid references / recommendations of products) on what to put in. Some examples:

G4 prefilter with F7 (captures >= 2um)
G4 prefilter with Semi HEPA E10/11/12
G4 prefilter with HEPA H13
Active carbon filter, combined with one of the above (not sure what they do)

I probably need to keep windows closed when the ventilation system isn't running, as otherwise the same pollutants will drift in. I'll also need to turn up the power of our ventilation fan, currently set on half, as these filters will reduce air throughput.

Ming Fans has an F7 filter box, I would just have to check to see if it can have multiple filters in i.

Air Quality Testing and Filtering

You can also buy appliances that sit in the house filtering the air. I'm not sure if they're worthwhile if the air intake is filtered. Any thoughts?

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#2391470 14-Jan-2020 09:13

I would get your current air (both outside and the inside) tested so you have a base line to work from. then you can decide if you need more filtration.....

As for the studies based on the Gas Leak, it was in the San Fernando Valley, which generally has pretty rubbish air quality as its a highly urbanised environment surrounded by decent ranges of hills,

timmmay

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#2391472 14-Jan-2020 09:17

How would you get air tested, without spending a fortune? I did a quick Google, there are firms around that do it, but no price on their website often means "if you have to ask, you don't want to know".

Putting in a new filter box with a couple of filters might cost $200, I expect air quality testing could cost significantly more than that.

Yoban

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#2391514 14-Jan-2020 09:52

I have a friend who has installed one of these (https://www2.purpleair.com/collections/air-quality-sensors/products/purpleair-pa-ii) to monitor air quality around his home and contribute to the global collection of data.

It also collects temperature, humidity, etc. and this feeds his HA system.

The mapping is very interesting https://www.purpleair.com/map?opt=1/mAQI/a10/cC0#1/15.3/-30

This would help with base lining your area.

timmmay

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#2391522 14-Jan-2020 10:09

Looks like about US$250 to get a sensor in, which would be interesting, but fairly sure I couldn't get this past my wife. The purple air thing looks pretty cool though.

The cost to put in a filter box with a HEPA filter is about NZ$200, so it's cheaper to improve the air quality than it is to quantify and monitor the air quality.

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#2391534 14-Jan-2020 10:25

timmmay:

Looks like about US$250 to get a sensor in, which would be interesting, but fairly sure I couldn't get this past my wife. The purple air thing looks pretty cool though.

The cost to put in a filter box with a HEPA filter is about NZ$200, so it's cheaper to improve the air quality than it is to quantify and monitor the air quality.

do i need a positive pressure ventilation system fir this to work? is that what you have installed already?

my house is dusty because the outside is dusty. i need a way to reduce dust in the house!

timmmay

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#2391537 14-Jan-2020 10:28

Batman:

do i need a positive pressure ventilation system fir this to work? is that what you have installed already?

my house is dusty because the outside is dusty. i need a way to reduce dust in the house!

Any type of ventilation system should work, positive pressure or heat recovery ventilation. If air is being recirculated (which it probably isn't in a home system) you only need the fine filter on the input, recirculated air can use a coarser filter.

Putting a filter on our ventilation system definitely reduced the dust indoors. You do need to keep windows closed and ensure the house is adequately sealed of course. For simply catching dust a G4 filter is probably adequate, F7 would be heaps. The finer the filter, the more it catches, and the more often it needs to be changed.

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Yoban

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#2391538 14-Jan-2020 10:31

timmmay:

Looks like about US$250 to get a sensor in, which would be interesting, but fairly sure I couldn't get this past my wife. The purple air thing looks pretty cool though.

The cost to put in a filter box with a HEPA filter is about NZ$200, so it's cheaper to improve the air quality than it is to quantify and monitor the air quality.

yeah I hear you as I too would like one at home. Definitely an element of geekness to it. My friend is also using to decide on when to open the windows for fresh air or run ventilation/heatpump system.

neb

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#2392095 14-Jan-2020 17:07

wellygary:
I would get your current air (both outside and the inside) tested so you have a base line to work from. then you can decide if you need more filtration.....

You can buy endless numbers of cheap Chinese-made air testers for vastly less than what it'd cost to get it professionally done. OK, they're cheap Chinese-made air testers, but they'll at least give you an idea of what you're facing now, and afterwards if you go for filtration.

neb

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#2392096 14-Jan-2020 17:11

Yoban:
I have a friend who has installed one of these (https://www2.purpleair.com/collections/air-quality-sensors/products/purpleair-pa-ii) to monitor air quality around his home and contribute to the global collection of data.

That's quite pricey for a particulate matter counter (the pressure, temp, etc is essentially free, so it's really just a PM counter). Admittedly it's a good-quality PM sensor, but for that price you can get ones with VOC/CO2/etc sensors as well, and you'd want at least VOC alongside the PM.

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#2392105 14-Jan-2020 17:41

timmmay:

Looks like about US$250 to get a sensor in, which would be interesting, but fairly sure I couldn't get this past my wife. The purple air thing looks pretty cool though.

The cost to put in a filter box with a HEPA filter is about NZ$200, so it's cheaper to improve the air quality than it is to quantify and monitor the air quality.

But you might be near a Wellington Regional Council air testing site. They are ostensibly selected to be representative of the area.

Page 28 of the following report has a list of air testing sites with maps a few pages further on in the appendices:

https://www.gw.govt.nz/assets/Our-Environment/Environmental-monitoring/Environmental-Reporting/Traffic-related-air-quality-indicator-201617.pdf

For reporting on the indicator to be unbiased it is critical that the locations selected for monitoring within each site category broadly represent what could be expected across the region and not an atypical local impact.

timmmay

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#2392171 14-Jan-2020 18:28

neb:
wellygary:

I would get your current air (both outside and the inside) tested so you have a base line to work from. then you can decide if you need more filtration.....

You can buy endless numbers of cheap Chinese-made air testers for vastly less than what it'd cost to get it professionally done. OK, they're cheap Chinese-made air testers, but they'll at least give you an idea of what you're facing now, and afterwards if you go for filtration.

@neb Can you recommend one that's moderate price and reliable? Not sure I'd pay much for one, but a cheap one probably isn't going to do a great job.

Hammerer:

But you might be near a Wellington Regional Council air testing site. They are ostensibly selected to be representative of the area.

No such luck, but thanks for the link.

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neb

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#2392249 14-Jan-2020 23:35

timmmay:
@neb Can you recommend one that's moderate price and reliable? Not sure I'd pay much for one, but a cheap one probably isn't going to do a great job.

It'll be fine, for two reasons, firstly "cheap" doesn't mean nasty, it just means that this stuff is quite inexpensive, for example the widely-used Bosch BME680, which does temperature, pressure, humidity, and air quality (PM) - sound familiar? - is under $20 in 10+ quantities, half that for a full 5K reel, and secondly you're not after lab-quality results, you just want to know whether you need to filter your air or not.

So really, any cheap device that measures PM will do, there are Chinese no-names on eBay for around the NZD40 mark. If you want to do it properly, i.e. WiFi-based monitoring of PM2.5, PM10, TVOC, CO2, CO, Formaldehyde, etc, you're looking at $200+. Also, I haven't yet found a product that works properly, all of them have issues, usually related to bad software (crappy WiFi connectivity, unstable apps, etc).

timmmay

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#2392283 15-Jan-2020 07:15

Thanks @neb. You can get pretty ones that might be good to leave out, like this and this both around $50, which only to PM2.5 detection. You can also get ones like:

Do you think there's any point getting on that tests TVOC / HCHO / CO2 or better to get a basic one that looks nice that does PM2.5? I figure you might recognise the sensor models or something in them and be able to give more guidance than my "that one looks nice".

If I get one it'll probably be used occasionally for a week, then put in a drawer and used once a year. Or sold.

neb

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#2392550 15-Jan-2020 12:12

I can't recommend any from direct knowledge, but the 8-in-1 was one of the ones I saw, incredibly cheap and nasty but should do the job. Be careful with the USB one, I saw that too but if you read the fine print you'll see you need to explicitly select the one that does PM, the default is VOC only.

Point is, if you're going to toss it in a drawer after use, and maybe pull it out once a year to check your filters are working, then the only deciding factor is price, you don't want to spend $100 on something like that.

If you're of a DIY bent you could also just get the sensors from Sparkfun or Adafruit or similar, e.g. this CCS811, which is VOC not PM, hmm, thought I saw a PM sensor there once, there's only this one which is twice the cost of the Chinese eBay one, and the Adafruit one is the same cost, just for the sensor alone. So cheap Chinese may be the best bet.

neb

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#2392551 15-Jan-2020 12:15

Ah, and for the VOC question: Probably not worth the extra cost, and for the cheap ones there'll be a single cheap VOC sensor and they'll estimate everything else based on VOC, so don't expect much. There's a reason why there's a gap from the $20-40 to the $200+ devices, apart from the buggy WiFi and whatnot they're also adding sensors specific to what they're measuring.

If you're really serious about it, here's the best-quality one I've found so far, but they're not going to make funding unfortunately.

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