{"id":12863,"date":"2024-08-19T19:17:51","date_gmt":"2024-08-19T11:17:51","guid":{"rendered":"https:\/\/smartairfilters.com\/?p=12863"},"modified":"2024-08-19T19:17:54","modified_gmt":"2024-08-19T11:17:54","slug":"air-purifier-pre-filter-useful","status":"publish","type":"post","link":"https:\/\/smartairfilters.com\/en\/blog\/air-purifier-pre-filter-useful\/","title":{"rendered":"Why Pre Filter Air Purifiers Might Do More Harm Than Good?"},"content":{"rendered":"<p>Most purifiers on the market come with a pre-filter. That would make one think that pre-filters must be a good thing, right?<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img fetchpriority=\"high\" decoding=\"async\" width=\"1000\" height=\"667\" src=\"https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2019\/04\/Prefilter-\u5927\u70ae.jpg\" alt=\"Do air purifiers need pre-filter\" class=\"wp-image-7847\" style=\"width:900px\" srcset=\"https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2019\/04\/Prefilter-\u5927\u70ae.jpg 1000w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2019\/04\/Prefilter-\u5927\u70ae-300x200.jpg 300w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2019\/04\/Prefilter-\u5927\u70ae-768x512.jpg 768w\" sizes=\"(max-width: 1000px) 100vw, 1000px\" \/><\/figure><\/div>\n\n\n<p>However, most purifier companies also love to sell people <a href=\"https:\/\/twitter.com\/SmartAirFilters\/status\/1192521669061025793?s=20\">6-stage filtration<\/a>, or no &#8211; 7-stage filtration! But the science behind purifiers is surprisingly simple. <a href=\"https:\/\/smartairfilters.com\/en\/blog\/what-combination-of-air-filters-do-i-need-to-protect-against-everything\/\">Two types of filters will protect you<\/a> against virtually every type of air pollutant out there. But what about a pre-filter?<\/p>\n\n\n\n<figure class=\"wp-block-embed aligncenter is-type-rich is-provider-twitter wp-block-embed-twitter\"><div class=\"wp-block-embed__wrapper\">\n<blockquote class=\"twitter-tweet\" data-width=\"550\" data-dnt=\"true\"><p lang=\"en\" dir=\"ltr\">Purifier companies sell their 6 stage&#8211;no, 7 stage filtration technology! Here&#39;s why two filters are all you need:<a href=\"https:\/\/t.co\/feMQegmJXy\">https:\/\/t.co\/feMQegmJXy<\/a> <a href=\"https:\/\/twitter.com\/hashtag\/AirPollution?src=hash&amp;ref_src=twsrc%5Etfw\">#AirPollution<\/a> <a href=\"https:\/\/twitter.com\/hashtag\/Health?src=hash&amp;ref_src=twsrc%5Etfw\">#Health<\/a> <a href=\"https:\/\/twitter.com\/hashtag\/OpenData?src=hash&amp;ref_src=twsrc%5Etfw\">#OpenData<\/a> <a href=\"https:\/\/t.co\/HG5P4hnoa9\">pic.twitter.com\/HG5P4hnoa9<\/a><\/p>&mdash; Smart Air (@SmartAirFilters) <a href=\"https:\/\/twitter.com\/SmartAirFilters\/status\/1120485031359799296?ref_src=twsrc%5Etfw\">April 23, 2019<\/a><\/blockquote><script async src=\"https:\/\/platform.twitter.com\/widgets.js\" charset=\"utf-8\"><\/script>\n<\/div><\/figure>\n\n\n\n<p>When we were designing the world&#8217;s <span><a href=\"http:\/\/smartairfilters.com\/sqair\">most cost-effective purifier<\/a><\/span>, we decided to put this question to the test. We ran over 1,000 hours of tests on air purifiers with and without pre-filters to test whether pre-filters would actually make air breathers better off. Here\u2019s what we found.<\/p>\n\n\n\n<h2 class=\"wp-block-heading has-text-align-center\">What&nbsp;is a Pre-Filter?<\/h2>\n\n\n\n<p>A pre-filter is the initial filtration layer in an air purifier or HVAC system. Its main purpose is to capture larger particles like dust and hair, preventing them from clogging the HEPA filter.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img decoding=\"async\" width=\"831\" height=\"496\" src=\"https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/pre-filter-capture-air-purifier-dust-hairs.jpg\" alt=\"pre filter capture air purifier dust hairs\" class=\"wp-image-12864\" style=\"width:auto;height:500px\" srcset=\"https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/pre-filter-capture-air-purifier-dust-hairs.jpg 831w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/pre-filter-capture-air-purifier-dust-hairs-600x358.jpg 600w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/pre-filter-capture-air-purifier-dust-hairs-300x179.jpg 300w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/pre-filter-capture-air-purifier-dust-hairs-768x458.jpg 768w\" sizes=\"(max-width: 831px) 100vw, 831px\" \/><\/figure><\/div>\n\n\n<p>Of course, HEPA filters have no problem capturing these large particles, so the pre-filter will NOT increase the effectiveness of the purifier. Instead, the idea is that it should increase the lifespan. The great thing about pre-filters is they can be washed and cleaned periodically, <a href=\"https:\/\/smartairfilters.com\/en\/blog\/wash-clean-hepa\/\">unlike HEPA filters<\/a>.<\/p>\n\n\n\n<h3 class=\"wp-block-heading has-text-align-center\">Pre-filters vs. HEPA filters<\/h3>\n\n\n\n<p>A typical pre-filter has an efficiency range of 20% to 70%, capturing particles sized between 3 and 10 microns, making it suitable for pet owners. In contrast, a HEPA filter can remove 99.97% of mold, bacteria, pollen, and dust from the air, filtering particles as small as 0.3 microns.<\/p>\n\n\n\n<h3 class=\"wp-block-heading has-text-align-center\">The Problem with Pre-Filters<\/h3>\n\n\n\n<p>Pre-filters have costs. Because they add an extra layer of resistance to your air purifier, they can reduce airflow and increase noise.<\/p>\n\n\n\n<p>So we&#8217;ve got a potential benefit (lifespan) and a cost (air resistance). We can make theoretical arguments all day in favor of one or the other. The real way to answer this question is to put it to the test.<\/p>\n\n\n\n<h3 class=\"wp-block-heading has-text-align-center\">Air Purifier Pre-Filter Tests: With vs. Without<\/h3>\n\n\n\n<p>In our Smart Air lab in Beijing, clean air engineer Vitalii ran a series of effectiveness (CADR) tests on the Sqair with and without a pre-filter. In the test, we burn cigarettes in a closed room to produce PM2.5 pollution and track how long it takes the purifier to clean the air.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img decoding=\"async\" width=\"739\" height=\"359\" src=\"https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/air-purifier-pre-filter-test.jpg\" alt=\"air purifier pre-filter test\" class=\"wp-image-12865\" srcset=\"https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/air-purifier-pre-filter-test.jpg 739w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/air-purifier-pre-filter-test-600x291.jpg 600w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/air-purifier-pre-filter-test-300x146.jpg 300w\" sizes=\"(max-width: 739px) 100vw, 739px\" \/><\/figure><\/div>\n\n\n<p>Averaging across multiple, here is how the pre-filter affected performance:<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"1856\" height=\"1388\" src=\"https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/Air-purifier-with-Pre-filter-less-effective-than-without-pre-filter-.jpg\" alt=\"Air purifier with Pre-filter less effective than without pre-filter\" class=\"wp-image-12868\" style=\"width:900px\" srcset=\"https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/Air-purifier-with-Pre-filter-less-effective-than-without-pre-filter-.jpg 1856w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/Air-purifier-with-Pre-filter-less-effective-than-without-pre-filter--600x449.jpg 600w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/Air-purifier-with-Pre-filter-less-effective-than-without-pre-filter--1024x766.jpg 1024w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/Air-purifier-with-Pre-filter-less-effective-than-without-pre-filter--300x224.jpg 300w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/Air-purifier-with-Pre-filter-less-effective-than-without-pre-filter--768x574.jpg 768w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/Air-purifier-with-Pre-filter-less-effective-than-without-pre-filter--1536x1149.jpg 1536w\" sizes=\"(max-width: 1856px) 100vw, 1856px\" \/><\/figure><\/div>\n\n\n<p>The results are pretty conclusive. Adding a pre-filter to The Sqair reduces effectiveness by 40%.<\/p>\n\n\n\n<h3 class=\"wp-block-heading has-text-align-center\">How Pre-Filters Affect HEPA Filter Lifespan<\/h3>\n\n\n\n<p>Hang on. The purpose of a pre-filter is to increase the lifespan of the HEPA filter, not to increase effectiveness. So what about lifespan?<\/p>\n\n\n\n<p>To answer this question, we set up a new experiment. In this test, we ran 3 Sqair purifiers 24\/7 over 2 months to test if a pre-filter really increases the lifespan of the HEPA.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"1379\" height=\"765\" src=\"https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/Air-purifier-pre-filter-tests-lifespan-of-HEPA-filter-1-e1648050458600.jpeg\" alt=\"Air purifier pre-filter tests lifespan of HEPA filter\" class=\"wp-image-12870\" style=\"object-fit:cover;width:900px;height:500px\" srcset=\"https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/Air-purifier-pre-filter-tests-lifespan-of-HEPA-filter-1-e1648050458600.jpeg 1379w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/Air-purifier-pre-filter-tests-lifespan-of-HEPA-filter-1-e1648050458600-600x333.jpeg 600w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/Air-purifier-pre-filter-tests-lifespan-of-HEPA-filter-1-e1648050458600-1024x568.jpeg 1024w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/Air-purifier-pre-filter-tests-lifespan-of-HEPA-filter-1-e1648050458600-300x166.jpeg 300w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/Air-purifier-pre-filter-tests-lifespan-of-HEPA-filter-1-e1648050458600-768x426.jpeg 768w\" sizes=\"(max-width: 1379px) 100vw, 1379px\" \/><\/figure><\/div>\n\n\n<p>We ran three machines:<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong> Nothing: <\/strong>Sqair without a pre-filter<\/li>\n\n\n\n<li><strong> Ideal condition pre-filter: <\/strong>Sqair with a pre-filter that we replaced every week (like washing it every week, but better!)<\/li>\n\n\n\n<li><strong> Realistic pre-filter: <\/strong>Sqair with a pre-filter we didn\u2019t wash or replace (how we see most people use their air purifier)<\/li>\n<\/ol>\n\n\n\n<p>We ran effectiveness (CADR) tests of all 3 Sqairs every 65 hours. Here&#8217;s what happened to their effectiveness over the 2 months.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"2117\" height=\"1263\" src=\"https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/Pre-Filter-effect-on-performance-over-time.jpg\" alt=\"Pre-Filter effect on performance over time\" class=\"wp-image-12871\" style=\"width:900px\" srcset=\"https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/Pre-Filter-effect-on-performance-over-time.jpg 2117w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/Pre-Filter-effect-on-performance-over-time-600x358.jpg 600w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/Pre-Filter-effect-on-performance-over-time-1024x611.jpg 1024w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/Pre-Filter-effect-on-performance-over-time-300x179.jpg 300w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/Pre-Filter-effect-on-performance-over-time-768x458.jpg 768w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/Pre-Filter-effect-on-performance-over-time-1536x916.jpg 1536w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/12\/Pre-Filter-effect-on-performance-over-time-2048x1222.jpg 2048w\" sizes=\"(max-width: 2117px) 100vw, 2117px\" \/><\/figure><\/div>\n\n\n<p>The two Sqairs with a pre-filter had lower effectiveness at the start, but that\u2019s to be expected from the earlier test. The real question is: does changing the pre-filter ever push performance above the &#8220;unprotected&#8221; Sqair?<\/p>\n\n\n\n<p>Here&#8217;s the shocking result. Even after 1,000 hours, when effectiveness dropped 50% (which is when the HEPA should be replaced), the purifier without a pre-filter <strong>still <\/strong>outperformed the purifier with the frequently changed pre-filter.<\/p>\n\n\n<div class='bottom-line'><div class='bottom-line-top'>Bottom Line<\/div><div class='bottom-line-title'>&lt;strong&gt;Bottom line on The Effectiveness of Pre-Filters&lt;\/strong&gt;<\/div><div class='bottom-line-content'>The data showed that adding a pre-filter to the Sqair decreases its effectiveness, without increasing the lifespan of the HEPA filter.<\/p>\n<p>Even if we compare the pre-filter that was changed constantly and the pre-filter that wasn&#8217;t changed, the difference in effectiveness was small. At the end of the test, the difference in effectiveness was less than 10%. This suggests that the benefit of cleaning the pre-filter is small.<\/div><div class='bottom-line-last'>Smart Air<\/div><\/div>\n\n\n\n<p><\/p>\n\n\n\n<h3 class=\"wp-block-heading has-text-align-center\">Possible Exceptions For Using Pre-Filters?<\/h3>\n\n\n\n<p>There might be exceptions. Since dogs and cats shed lots of fur, pet owners might still benefit from using a pre-filter. We plan to run tests in a pet owner&#8217;s home to see whether the results are any different.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"640\" height=\"640\" src=\"https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/09\/Smart-Air-Blast-Mini-air-purifier-and-pet-dog-in-office.jpg\" alt=\"Smart Air Blast Mini air purifier and pet dog in office\" class=\"wp-image-12246\" srcset=\"https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/09\/Smart-Air-Blast-Mini-air-purifier-and-pet-dog-in-office.jpg 640w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/09\/Smart-Air-Blast-Mini-air-purifier-and-pet-dog-in-office-600x600.jpg 600w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/09\/Smart-Air-Blast-Mini-air-purifier-and-pet-dog-in-office-300x300.jpg 300w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2020\/09\/Smart-Air-Blast-Mini-air-purifier-and-pet-dog-in-office-60x60.jpg 60w\" sizes=\"(max-width: 640px) 100vw, 640px\" \/><\/figure><\/div>\n\n\n<p>Also, large centrifugal fans like the fan in the Blast are stronger, meaning the pre-filter won&#8217;t affect airflow as much.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"1500\" height=\"1000\" src=\"https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2017\/10\/91A0057-1.jpg\" alt=\"Blast purifier in situ in cafe\" class=\"wp-image-4863\" style=\"object-fit:cover;width:900px;height:500px\" srcset=\"https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2017\/10\/91A0057-1.jpg 1500w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2017\/10\/91A0057-1-300x200.jpg 300w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2017\/10\/91A0057-1-768x512.jpg 768w, https:\/\/smartairfilters.com\/wordpress\/wp-content\/uploads\/2017\/10\/91A0057-1-1024x683.jpg 1024w\" sizes=\"(max-width: 1500px) 100vw, 1500px\" \/><\/figure><\/div>","protected":false},"excerpt":{"rendered":"<p>Most purifiers on the market come with a pre-filter. That would make one think that pre-filters must be a good thing, right? However, most purifier companies also love to sell people 6-stage filtration, or no &#8211; 7-stage filtration! But the science behind purifiers is surprisingly simple. Two types of filters &#8230; <\/p>\n<p class=\"read-more-container\"><a title=\"Why Pre Filter Air Purifiers Might Do More Harm Than Good?\" class=\"read-more button\" href=\"https:\/\/smartairfilters.com\/en\/blog\/air-purifier-pre-filter-useful\/#more-12863\" aria-label=\"Read more about Why Pre Filter Air Purifiers Might Do More Harm Than Good?\">Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":33147,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_relevanssi_hide_post":"","_relevanssi_hide_content":"","_relevanssi_pin_for_all":"","_relevanssi_pin_keywords":"","_relevanssi_unpin_keywords":"","_relevanssi_related_keywords":"","_relevanssi_related_include_ids":"","_relevanssi_related_exclude_ids":"","_relevanssi_related_no_append":"","_relevanssi_related_not_related":"","_relevanssi_related_posts":"7830,11976,22029,13492,20657,6631","_relevanssi_noindex_reason":"","footnotes":""},"categories":[190,259],"tags":[444,525,526,120,232],"class_list":["post-12863","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-air-purifiers","category-filters","tag-hepa-filter","tag-lifespan","tag-longevity","tag-pre-filter","tag-wash","resize-featured-image"],"acf":[],"_links":{"self":[{"href":"https:\/\/smartairfilters.com\/en\/wp-json\/wp\/v2\/posts\/12863","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/smartairfilters.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/smartairfilters.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/smartairfilters.com\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/smartairfilters.com\/en\/wp-json\/wp\/v2\/comments?post=12863"}],"version-history":[{"count":7,"href":"https:\/\/smartairfilters.com\/en\/wp-json\/wp\/v2\/posts\/12863\/revisions"}],"predecessor-version":[{"id":33154,"href":"https:\/\/smartairfilters.com\/en\/wp-json\/wp\/v2\/posts\/12863\/revisions\/33154"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/smartairfilters.com\/en\/wp-json\/wp\/v2\/media\/33147"}],"wp:attachment":[{"href":"https:\/\/smartairfilters.com\/en\/wp-json\/wp\/v2\/media?parent=12863"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/smartairfilters.com\/en\/wp-json\/wp\/v2\/categories?post=12863"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/smartairfilters.com\/en\/wp-json\/wp\/v2\/tags?post=12863"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}