Literature round-up, December 2012

By Brent Stephens on December 16, 2012

Well, I had grand visions of posting links to new literature that I find interesting on a more regular basis than I have been doing. I was shooting for monthly posts, but the last time I posted was back in September! Better late than never I suppose.

Here are a few studies that I’ve come across over the last few months that will hopefully spark some interest:

• Study on economic impacts of energy service companies – Interesting study on the economic impacts of energy service companies (ESCOs). ESCOs are generally private companies that operate on a model of selling energy performance upgrades to building owners whereby the building owners are motivated to do so because of they are promised long-term energy savings. This study shows that the ESCO industry continued strong growth even through the recession. Additionally, energy payback times are getting longer, suggesting that low-hanging fruit is being plucked in these areas and that more complex (and more expensive) systems with longer rates of returns are being utilized more (Energy Policy).
• Factors influencing variability in infiltration of PM2.5 – Wonderful paper dissecting a bunch of indoor-outdoor airborne particle measurements that were made in and around about 40 homes in Canada a few years ago. This same team reported their initial findings in several recent papers, but this one tries to explain why some homes had far higher or lower indoor levels of outdoor PM2.5 and ultrafine particles (UFPs). These folks do great work and they show that (quite intuitively) window-opening behaviors, presence and operation of HVAC systems and filters, and the age of homes predicted a good portion of the variation across homes (Atmospheric Environment).
• Household light makes global heat – This study presents some new lab and field measurements of kerosene wick lamps, which are a significant source of particulate matter emissions, including black carbon (BC), particularly in developing regions of the world. They show tremendously high emission rates of BC, which makes kerosene lamps important in terms of climate forcing and an important contributor to global warming. We’ve already  known a lot about the health and climate impacts of cookstoves in developing regions, but this makes one more important combustion source that needs to be reckoned with. (Environmental Science and Technology).
• Size and concentration of droplets generated by coughing in human subjects – I’ve been working on a project for the National Air Filtration Association over the last few weeks attempting to quantify what types of effects HVAC filtration may have on the transmission of infectious airborne diseases. In doing so, I’ve come across a few really interesting articles (I’ve already blogged about one of those). In my review, I’ve learned about the aerosols that are expelled from our bodies when we breath, speak, cough, or sneeze. There’s actually a surprising lack of information on the concentrations and sizes of these emitted particles, but this study did a fine job of measuring the particle size distributions of expelled droplets from about 50 human subjects. Very interesting stuff and extremely important for understanding how disease (including influenza and the common cold virus) is transmitted. These researchers showed that a large majority of the droplet nuclei (a fancy word for droplets that have been expelled and then had surrounding liquid evaporated) exist within the 0.7 to 2.1 µm size range (Journal of Aerosol Medicine).