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[49.195.51.32]) by smtp.gmail.com with ESMTPSA id cu4sm1087847pjb.18.2020.12.23.20.39.35 for (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Wed, 23 Dec 2020 20:39:36 -0800 (PST) Received: from james by esk with local (Exim 4.90_1) (envelope-from ) id 1ksIPT-0004wU-2o; Thu, 24 Dec 2020 15:39:31 +1100 From: James Cameron To: Microcontroller discussion list - Public. Sender: "piclist-bounces@mit.edu" Date: Wed, 23 Dec 2020 20:39:31 -0800 Subject: Re: [OT] Air quality, Dust, TVOC? Thread-Topic: [OT] Air quality, Dust, TVOC? Thread-Index: AdbZsBKuIkXWgdPmQzqiV5D9eetRSg== Message-ID: <20201224043931.GA12417@laptop.org> List-Help: List-Subscribe: , List-Unsubscribe: , In-Reply-To: <34048fd7-f3ad-b5f0-dc4a-948453b2b2c3@sentry.org> Reply-To: Microcontroller discussion list - Public. Accept-Language: en-US X-MS-Exchange-Organization-AuthAs: Anonymous X-MS-Exchange-Organization-AuthSource: TS500.efplus4.local X-MS-Has-Attach: X-Auto-Response-Suppress: All X-MS-Exchange-Organization-SenderIdResult: Pass X-MS-Exchange-Organization-PRD: mit.edu X-MS-TNEF-Correlator: received-spf: Pass (protection.outlook.com: domain of laptop.org designates 209.85.216.41 as permitted sender) receiver=protection.outlook.com; client-ip=209.85.216.41; helo=mail-pj1-f41.google.com; dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=laptop-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:subject:message-id:mime-version:content-disposition :in-reply-to:user-agent; bh=qEWSupX6xFzns0dUMvUO1BwUHc/ns9JEvstOp3/nRYc=; b=jz/wHOq+yqh+mUkRifBUIo/UXVuiYsyIo+Iz1YQzWJlQF+VgpjxfCa3lOsDxhCa1ZT I8Ff3ktB78Td6CvCvT7mGBAZR+tlLptC3ixZ5uNqlJ9mgUlqMSmwzLiY1k58p8yADIoT E5dB10HlmotFX1FrUhsvUZbzlcr+4igp2QYbTF2yoT/by77ajpbO3+JtCuIotT5Haql/ 4d6gqyxO+NN/FHiUizBO2oLRt/rBmom/0+f3fTu/xMm0KoCT+TfhEfSsF7l4pYq/VhwI gfU3xKzF0TF3bpmUHzRFT1Mb+TbudBQcAmMnXIQ7F4U04+mYR55JYFy3IPhgXs+1DrCm xicw== authentication-results: spf=pass (sender IP is 209.85.216.41) smtp.mailfrom=laptop.org; mit.edu; dkim=pass (signature was verified) header.d=laptop-org.20150623.gappssmtp.com; mit.edu; dmarc=bestguesspass action=none header.from=laptop.org; user-agent: Mutt/1.9.4 (2018-02-28) errors-to: piclist-bounces@mit.edu list-id: "Microcontroller discussion list - Public." list-post: x-beenthere: piclist@mit.edu x-mailman-version: 2.1.6 x-received: by 2002:a17:90a:3d0b:: with SMTP id h11mr2647381pjc.188.1608784776876; Wed, 23 Dec 2020 20:39:36 -0800 (PST) x-topics: [OT] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 On Thu, Dec 24, 2020 at 11:39:21AM +0800, Justin Richards wrote: > Regarding humidity, do you think high humidity is better or worse for > allergies? Apart from aforesaid mucociliary clearance, both high humidity and low humidity have downsides. High humidity triggers any mould to grow and therefore release spores. Water can also contained dissolved substances, hence rusting cars near the sea. Sudden low humidity dries the respiratory tract; it can take a few days for the body to compensate, but it does, so constant low humidity can be adapted to. Curiously, COVID-19 aerosols hang around for longer in drier air. https://theconversation.com/the-144508 On Thu, Dec 24, 2020 at 03:02:03PM +1100, Trevor wrote: > I'm fairly convinced that our swampy deposits fine orange clay dust > throughout the house (curse of the Riverina). I can't otherwise > explain the fact that the dust is on every surface despite frequent > cleaning. > > While you'd expect that it might filter out dust when drawing hot > air through cardboard filters running with water, I'm not convinced > that it doesn't also suck in the dust through other gaps in the > housing. It's serviced every year and covered in winter to help > prevent smoke from next door's woodfire being spread throughout the > house. I've lived in a house with one of those evaporative air coolers. The filters we used were straw, which was wet with water from a bore. I tested by placing a tissue across a vent. I got dust from outside air, and from what was suspended in the bore water. For any filter that isn't to HEPA grade, I expect it will collect some of the dust by random collisions, but also release the dust once it has accumulated. Eventually the dust collection equals the dust release. If you're using town water supply, then you get to breath whatever the processing plant uses to bring it up to standard. I've heard rumour of walls changing colour based on decisions by the shire engineer to switch between river and bore while changing dosing. On the other hand, heat pump air conditioners usually have weak filters designed to prevent fouling of the heat exchanger, yet people often believe they can somehow filter small particles. My favourite design, not yet attempted, is an earth tube with a HEPA filter at the distant end, and another filter at the house to catch any mould spores. ;-) --=20 James Cameron https://quozl.linux.org.au/ --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .