Comments

Author Comment Last activity Moderation
guolivar "Short answer is NO ... longer answer is still no but with some reasons behind. In general the EPA (and any other regulatory body) needs A LOT of c..." | Read more » 9 months ago
guolivar "Thanks for the heads up @liz I've been working in air quality research for 20 years and I am yet to find a reliable "low-cost" NO2 sensor. There a..." | Read more » 9 months ago
guolivar "I'm sorry but as usual the time difference kills me. I could potentially listen in but at that time I cannot join the discussions (I'm too busy get..." | Read more » about 1 year ago
guolivar "Normalising is your friend when you have things with very different ranges. Depending on what you're looking for you can divide each column by its ..." | Read more » over 1 year ago
guolivar "This is very much dataset, project and software dependent. Sometimes I remove columns, other times I combine them (averaging, adding, etc), other ..." | Read more » over 1 year ago
guolivar "Great tear-down! I see that a lot of love went into the Sensiron design and I mostly agree with the comments ... the issue of the HEPA filter is m..." | Read more » over 1 year ago
guolivar "First, I haven't used the SPS30 so can't comment on specifics for those sensors. However, I have many years of experience working with aerosol meas..." | Read more » over 1 year ago
guolivar " The particle size distribution (mass, volume or number) is very variable and even though "on average" it's fairly stable, the day-to-day variabili..." | Read more » almost 2 years ago
guolivar "Short answer ... No. Long answer ... Absolutely no! I'll try to explain why, even though it sounds possible, the uncertainties are so large that t..." | Read more » almost 2 years ago
guolivar " Quickly to your question of: For example, the first 6 are two sets of PM1, PM2.5, and PM10 concentrations. the first set are labeled "standard", w..." | Read more » almost 2 years ago
guolivar " All the way in New Zealand we also use Gradko for all our passive tubes needs. " | Read more » almost 2 years ago
guolivar " It all depends on what your objectives are. You'll notice that most air quality monitoring stations (the regulatory ones) have wind measurements w..." | Read more » about 2 years ago
guolivar "Following on @jeffalk answer, please expand on your question. In my opinion (and I've worked in aerosol science for a number of years) the main poi..." | Read more » over 2 years ago
guolivar "As far as I know Plantower hasn't disclosed that (to be fair, I don't think any of the low-cost manufacturers has done either). From the field test..." | Read more » over 2 years ago
guolivar "Here is a page about the PMS5003 and 7003 ... https://aqicn.org/sensor/pms5003-7003/ The difference seems to be in their internal layout. In that ..." | Read more » over 2 years ago
guolivar "I'll try to unpack a couple of things here. The use of zero filters is standard practice as a quick check of particle instruments. It is used to t..." | Read more » over 2 years ago
guolivar "I'm sorry, this got buried in my inbox ... I don't even remember seeing a notification about the original question! The short answer is that I don'..." | Read more » over 2 years ago
guolivar "Great work @sagarpreet! This might get rambly because there is no right answer but I'll try to explain why and what then. The first thing you nee..." | Read more » over 2 years ago
guolivar "The description of the operating principle can be misleading. Optical particle measurements rely on intensity of scattering rather than "amount of..." | Read more » almost 3 years ago
guolivar "Some colleagues from Australia have been working on AirRater (https://airrater.org/) and we're working towards adapting it for specific projects. I..." | Read more » almost 3 years ago
guolivar "I tried to put a long answer here but it kept throwing errors so I wrote a note with my thoughts on this issue: https://publiclab.org/notes/guoliv..." | Read more » about 3 years ago
guolivar "Smoke particles (and by smoke I mean combustion products) come in sizes all the way down to 1nm (0.001micron) and in shapes that make it very trick..." | Read more » over 3 years ago
guolivar "You're right, the effect of humidity would be to change the "apparent" size but it's not just increasing the number of particles that now fall in t..." | Read more » over 3 years ago
guolivar "Yes, environmental conditions do affect the ability of an optical sensor, not too much to "see" a particle but rather to "size" it. All of these o..." | Read more » over 3 years ago