Humid summers, dry winters – at least until you go outside

from Engval et al (2005)

Above is a plot of the average relative humidity (RH) inside a house, for each of the 12 months of the year. The relative humidity is the amount of water in the air, as a % of the maximum amount of water that the air can hold. So 0% RH is completely dry air – no water – while 100% RH is air completely saturated with water. The RH is basically what people call the humidity, in the sense that when they say it is very humid, they mean a RH that is close 100%. The data above was collected in Sweden by Engvall and coworkers.

More

Open access publishing: Where did it all go wrong?

Twenty five years ago, in 1997, I published my first green open access paper* – although this is so long ago that the term ‘green open access’ wasn’t used then. Open access publishing, is making available a paper (typically presenting the results of taxpayer funded research) so that everyone can read it for free. I can’t remember much about that paper – it was a long time ago – but the paper is green open access because as well as being published in a journal, it is on the arXiv server – where everyone can read it for free. Submission to arXiv has always been pretty slick and well designed, so I suspect it was easy to do. It required zero paper work and cost nothing.

More

How likely are you to get COVID in a sauna?

We don’t know the answer to this question. Over the two years of the pandemic there has been a fair amount of debate on how far COVID-19 can spread, with some people, incorrectly, thinking that it rarely travels more than a metre or two across a room. But we have clear examples, such as in a restaurant in Guangzhou, where COVID-19 spread across a room. So, I hope this debate is settled, you can catch COVID-19, and almost certainly, flu, from across a room. We also know that masks offer some protection, with FFP2/N95 masks offering much more protection than cloth masks.

More

From a Nobel prize winner to a dislike of Excel

This week, apart from the usual teaching and research, I both attended the Department’s annual Lewis Elton lecture, and read a blog post that takes a swipe at Excel. The lecture was given by Prof Adam Reiss (Johns Hopkins) who shared the 2011 Nobel prize in physics with Saul Perlmutter and Brian Schmidt, for showing that the expansion of the universe appears to be accelerating. This surprised a lot of people but appears to be true, not only is the Universe continually getting bigger and bigger but the rate at which it is doing so, is also increasing. This surprise won the Nobel prize.

More

Evidence that masks work in practice, especially if they are the good ones: the N95/KN95/FFP2s

Above is a figure from a recent study published by the American government’s CDC (Centers for Disease Control and Prevention)*. Essentially, Andreko and coworkers studied two populations in California: one of 600 people who had just tested positive for COVID-19, and one of 1,100 who had not. They asked both sets of people about mask wearing while in public settings indoors (i.e., shops, workplaces, etc). Then they got the risk reduction from the numbers of mask wearers in the two populations. The idea being that if masks work you would expect a higher fraction of the 1,100 who don’t have COVD-19 to wear masks, than the 600 people who do. The way to read the figure is that they estimate that wearing an N95/KN95 (similar to FFP2, KF94, …) while indoors reduces your risk of catching COVID-19 by 83%.

More

Is NHS infection control misrepresenting the HSE, when it comes to masks?

Google recommended to me this article in Pulse: a publication for GPs. It made me wince quite a bit. A representative of the UK’s “NHS England national infection prevention and control team” was suggesting GPs and others wear surgical masks. The evidence is that FFP2s would be better, offer more protection. I was particularly struck by:

However, she [a “NHS England national infection prevention and control team member”] added that the UK Health and Safety Executive recommends healthcare professionals ‘should not use’ FFP2 masks and that ‘the only requirement to use them’ would be ‘if you couldn’t get FFP3’.

GPs should not routinely use FFP2 as surgical mask gives ‘very good protection’, Pulse, 19th Jan 2022

That is kind of true, the UK’s Health and Safety Executive says:

HSE’s current stance is that where there is a respiratory risk of infection use of FFP3 devices represents best practice, and where these are not available then FFP2 may be an acceptable, pragmatic compromise.

Evaluating the protection afforded by surgical masks against influenza bioaerosols (Research Report 619), Prepared by the Health and Safety Laboratory for the Health and Safety Executive 2008

So, the HSE (who are people in the UK government who understand masks – unlike apparently NHS infection prevention and control) are indeed advising against FFP2s when there is significant risk of infection. They are advising upgrading to a better mask. FFP3s are better than FFP2s. They are not recommending downgrading to the much worse surgical masks, as NHS national infection prevention and control is doing. Odd.

More

Teaching half the class

Last semester, teaching was on average about halfway back to normal, but for computing it was almost normal, apart from the masks, which weren’t a big deal. I think it went well. I introduced a little warm-up introductory informal lecture at the beginning. This was maybe 10 to at most 30 minutes in the computing lab, introducing and motivating that week’s Python Jupter notebook. Students voted with their feet and despite it being at 9 am attendance was good. I will do it again next year.

More

Many medics including Sir Chris Whitty don’t seem to understand how masks work

Today there was a COVID-19 press conference, with the Prime Minister Boris Johnson, and Sirs Chris Whitty and Patrick Valance. It is on YouTube. At about 38 minutes LBC’s Ben Kentish asked a couple of questions. Sir Chris Whitty gave what sounded to me like an excellent answer on vaccines, clear, authoritative, from the heart, and useful. Impressive. He was also also asked about some healthcare workers not getting FFP3 masks. Maybe the question was a little vague but the answer was certainly vague and he did imply that there was a debate about where an FFP3 was useful and where they are not.

More

How long does SARS-CoV-2 survive outside the body?

It may not be obvious that there is a connection between the air-conditioning units of Boeing airliners, and the survival of viruses, but there is. In the 1960s, an engineer called Proschan, while working for Boeing, was studying the failure statistics of the air-conditioning units in airliners. He was a pioneer of what is often called survival analysis – the branch of statistics that deals with failure/death. The same statistics applies both to failure of a machine, or death of an organism — and to the demise of a virus, which is perhaps somewhere between a machine and an organism.

More