{"id":12729,"date":"2020-04-24T20:16:00","date_gmt":"2020-04-25T00:16:00","guid":{"rendered":"http:\/\/airpurifierspecialist.com\/store\/?p=12729"},"modified":"2020-05-19T20:53:57","modified_gmt":"2020-05-20T00:53:57","slug":"humidity-plays-a-role-in-seasonal-spread-of-viruses-will-the-same-go-for-covid-19","status":"publish","type":"post","link":"https:\/\/airpurifierspecialist.com\/store\/humidity-plays-a-role-in-seasonal-spread-of-viruses-will-the-same-go-for-covid-19\/","title":{"rendered":"Humidity plays a role in seasonal spread of viruses. Will the same go for Covid-19?"},"content":{"rendered":"
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It\u2019s a mystery that has bothered scientists for decades: Why do temperate climates have a flu season? They\u2019ve floated many theories, from a drop in vitamin D levels<\/a> to people spending more time around each other indoors.<\/p>\n

According to a review study<\/a> published last month in the Annual Review of Virology, indoor humidity may play a surprising role.<\/strong><\/p>\n

\u201cDry air is a key factor that impairs a person\u2019s ability to fight off respiratory viral infections,\u201d says Akiko Iwasaki, an immunobiology professor at the Yale School of Medicine whose research group assembled the review.<\/p>\n

Viral seasonality is on more people\u2019s minds than usual at the moment, since some public health experts predict that the novel coronavirus could return each winter, like the flu. \u201cUnless we get this globally under control, there is a very good chance that it\u2019ll assume a seasonal nature,\u201d Anthony Fauci, the director of the United States\u2019 National Institute of Allergy and Infectious Diseases, said earlier this month<\/a>. If that happens and before we have a treatment or vaccine for Covid-19, additional people will die every time the virus resurges, while survivors are kept in lockdowns and quarantines.\u00a0<\/strong><\/p>\n

Several<\/a> studies<\/a> support<\/a> the idea that indoor humidity plays a role in seasonal disease transmission. When someone coughs or sneezes, they release tiny droplets<\/a> into the air (if they\u2019re sick, these droplets will contain virus). The bigger droplets typically fall before they get very far, but the tiniest droplets, called droplet nuclei, can go much farther<\/a>. In humid conditions, these tiny droplets don\u2019t evaporate as much, so they drop down<\/a> more quickly than they would in dry conditions. Virus-containing droplets that travel farther are more likely to infect a new host.<\/p>\n

Low humidity also impairs the host\u2019s ability to clear airborne viruses from their nose without getting infected, a fairly gross process of clearing snot from your nose (officially, it\u2019s called mucociliary clearance).<\/p>\n

\u201cNot much attention is being paid to the quality of air indoors,\u201d says Iwasaki, \u201cwhich is really where we live our lives.\u201d The review offers a hypothesis for how indoor humidity affects viral transmission, outlining both the physical process (the stability of viruses in a droplet, and their passage in the air as seen in animal models) and humidity\u2019s effect on immunological responses.<\/p>\n

While 40% to 60% relative humidity may be ideal to reduce viral transmission and infection in general, the Yale researchers suggest, previous studies<\/a> suggest<\/a> that indoor humidity in the winter months of temperate climates is below 25%\u2014pretty much ideal for a virus looking to infect people with reduced defenses. Even without stay-at-home orders in place, people spend about 90% of their time<\/a> indoors, so it\u2019s unlikely that simply spending more time inside contributes substantially to an increase in winter flu cases.<\/p>\n

But the relationship between viral seasonality and humidity isn\u2019t one-to-one: In tropical regions, the flu season often aligns<\/a> with the rainy season. \u201cIt\u2019d be nice if we could come up with a single hypothesis, a single explanation that covers tropical and temperate regions,\u201d says Linsey Marr, an engineering professor at Virginia Tech.<\/p>\n

And it\u2019s still too early to know what the results of this study might mean for the novel coronavirus that causes Covid-19. \u201cThis [study] talks about other coronaviruses that have been around for a while. And when there\u2019s new viruses, all bets are off with regard to seasonality,\u201d says Marr. \u201cAs the virus becomes more widespread, as more people are exposed, I could see it settling into a pattern typical of coronaviruses, which are more prevalent during the wintertime.\u201d<\/p>\n

As the study notes, researchers may have a better sense in the coming months. \u201cThe precise relationship between temperature, humidity, and Covid-19 will become more evident as the Northern Hemisphere reaches the summer months,\u201d the authors write.<\/p>\n

To help researchers understand how big a role relative humidity plays in disease transmission, says Marr, \u201cwe need more controlled studies both in animals and humans.\u201d Animal studies allow researchers to control aspects of the environment that would be too challenging (or unethical) to do with humans. \u201cThere have been separate studies looking at just transmission at different temperatures and humidities,\u201d she says. \u201cWe need to collect samples of the droplets containing viruses and see how well the viruses survive.\u201d<\/p>\n

Correction: <\/i><\/b>An earlier version of this article misstated the reason that tiny droplets travel farther under humid conditions. It\u2019s because they don\u2019t evaporate, not because they collect water from the air.<\/i><\/p>\n<\/div>\n

Read More<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

It\u2019s a mystery that has bothered scientists for decades: Why do temperate climates have a flu season? They\u2019ve floated many theories, from a drop in vitamin D levels to people spending more time around each other indoors.According to a review study published last month in the Annual Review of Virology, indoor humidity may play a…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[26],"tags":[],"_links":{"self":[{"href":"https:\/\/airpurifierspecialist.com\/store\/wp-json\/wp\/v2\/posts\/12729"}],"collection":[{"href":"https:\/\/airpurifierspecialist.com\/store\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/airpurifierspecialist.com\/store\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/airpurifierspecialist.com\/store\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/airpurifierspecialist.com\/store\/wp-json\/wp\/v2\/comments?post=12729"}],"version-history":[{"count":1,"href":"https:\/\/airpurifierspecialist.com\/store\/wp-json\/wp\/v2\/posts\/12729\/revisions"}],"predecessor-version":[{"id":16146,"href":"https:\/\/airpurifierspecialist.com\/store\/wp-json\/wp\/v2\/posts\/12729\/revisions\/16146"}],"wp:attachment":[{"href":"https:\/\/airpurifierspecialist.com\/store\/wp-json\/wp\/v2\/media?parent=12729"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/airpurifierspecialist.com\/store\/wp-json\/wp\/v2\/categories?post=12729"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/airpurifierspecialist.com\/store\/wp-json\/wp\/v2\/tags?post=12729"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}