“How can we quantify the lethality of exposure to a substance?”
People are exposed to potentially hazardous substances all the time, whether it’s traces of air pollution or bacterial growth on food. We also know that if exposure breaches a certain level, it becomes dangerous. So how can we quantify the lethality of exposure to a substance? Well, what if we divide the exposure level by the reference dose? This is how the Hazard Quotient works, and it is a very useful tool in toxicology.
“How far does air pollution rise after release from a stack?”
People often release waste air from a building stack. This air will rise to a certain height called the Plume Rise before moving in the direction of the wind. The higher the plume rises, the lower the amount of pollution that will fall on the ground. A higher exit temperature and faster exhaust speed lead to a larger sack height.
“How can we use water to remove harmful particles and gases from industrial air pollution?”
Industrial air pollution often contains toxic gases and harmful particulate matter at the same. Air pollution remediation systems typically concentrate on removing only one of these factors. Wet Scrubbers can handle both. Wet scrubbers first spray water or water-based solution droplets over the exhaust air. These droplets catch particulate matter and absorb toxic gases. Wet scrubbers usually use packing beds to maximize contact between the liquid and the exhaust air. The exhaust air will rise, cleansed of pollutants, and go through a mist eliminator to remove any remaining water droplets. People can recycle the dirtied liquid produced by these operations or treat it as wastewater. Wet scrubbers are a highly effective technology for treating industrial air pollution.
“How can we determine how to design a bag filter using one value?”
Baghouse filters are one of the most widely used industrial air pollution control technologies in the world. Their ability to stick particulate matter emissions onto bagged filters leads to their high efficiency. But how exactly do we design these machines? Well, what if we take the ratio of the volume of air moving through the cloth filters every minute vs the interior surface area of the cloth filters themselves? This value, termed the Air-to-Cloth Ratios for Baghouse Filters, determines how many volumes of air each square meter of the filters must handle. The higher the air-to-cloth ratio, the faster particles will move through the system, which increases the frequency of particulate matter clogging the filters and forcing more filter cleaning to occur.
“What’s the legal and scientific boundary for a water body?”
Water bodies will expand and contract over land, whether it’s a small river or a massive tidal bay. The point delineating the high tide mark from the land has massive geological and ecological implications, given the difference in water saturation. The Mean High Water Mark is the average high tide mark over a long period of time. The mean high water mark often delineates the legal and scientific boundary for a water body, making it very important to quantify.
“How can we remove particulate matter by sticking it on a wall?”
Particulate matter emissions are harmful to nearby communities. Consequently, people use technology to remove as much particulate matter as possible before emitting. One set of technologies sticks particulate matter on walls to form conglomerations, which can be removed later. TheseWall Collection Devices can work by forcing particles to drop from gravity, hit a wall due to sudden direction changes, or move due to electrostatic attraction. These wall collection devices help the health of countless towns around the world.
“How does temperature change with atmospheric height?”
The atmosphere’s properties change with height. One of these variables is the temperature. The Lapse Rate measures the rate of change of temperature with atmospheric height. The lapse rate is measured by taking the negative of the change in temperature divided by the change in height. If the lapse rate is positive, then temperature decreases with height, and vice versa for a negative lapse rate. Lapse rates are vital for measuring atmospheric stability.
“What are the advantages and disadvantages of sloping a green roof?”
Green roofs integrate stormwater management, biodiversity, building insulation, and aesthetic design all into one package. We can also pitch these green roofs at a slight angle to make Sloped Green Roofs. Sloped green roofs reduce ponding and may improve aesthetic appearance, but are also structurally and hydrologically more complicated. Stormwater runs off more from sloped green roofs, meaning roof plants may have to rely on other sources of water.
Construction sites often have sloping soil mounds. The bottom section with a gentle slope that meets the ground is known as the Soil Slope Toe. The soil slope toe is important because it often experiences the highest stress and is where erosion concentrates.
Isaac's Science Blog 