What is SPF, UV-A, and UV-B ?
Protecting our skin from sunlight is important, because it omits different types of ultraviolet radiation that causes sunburn, skin cancer, and other types of photo damage.
UV-A, can cause invisible damage and skin aging, without any reddening or pain Ultraviolet type B (UV-B) radiation causes sunburn and is easier to protect our skin from than UV-A.
Effective sunscreen has been developed since 1938 to protect the skin from harmful sunlight. Eventually, a worldwide standard for measuring the effectiveness of sunscreen was introduced in 1962, when the concept of Sun Protection Factor (SPF) was applied to all sunscreen products.
The SPF of a sunscreen is a laboratory measure of the effectiveness of sunscreen. The higher the SPF, the more protection a sunscreen offers against the sun’s ultraviolet rays. The SPF number indicates the time a person wearing sunscreen can be exposed to the sun before getting sunburn relative to the time a person without sunscreen can be exposed.
Someone who would burn after 15 minutes in the sun would expect to burn after 150 minutes if protected by a sunscreen with SPF 10. Different skin types require different SPF strengths. When choosing a sunscreen, make sure it is SPF 15 or higher, and select a broad-spectrum sunscreen that protects against UVB and UVA radiation.
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New Inexpensive Method of Water Purification with Pressurizing Ozone
The rainbow effect caused by varying thicknesses of oil film on water’s surface might be pretty to look at but is indicative of polluted water.
This “oil sheen” proves especially difficult to remove, even when the water is aerated with ozone or filtered through sand.
But now an engineer has developed an inexpensive new method to remove oil sheen by repeatedly pressurizing and depressurizing ozone gas, creating microscopic bubbles that attack the oil so it can be removed by sand filters.
It’s created by Andy Hong, uses two existing technologies – ozone aeration and sand filtration – but significantly changes the former method. Instead of attempting to turn the entire hydrocarbon (oil) content in the water into carbon dioxide and water by just bubbling ozone through polluted water, the new process converts it into a form that can be retained by sand filtration.
To achieve this Hong uses repeated cycles of pressurization of ozone and dirty water so the ozone saturates the water, followed by depressurization so the ozone expands into numerous micro bubbles in the polluted water.
Noxious Fumes Hotspots
Noxious Fumes level or dangerous smokes found in city streets has been so mounting.
A research led by Professor of Environmental Modeling Alison Tomlin at Leeds, has shown that air pollution levels change dramatically within small geographical areas – dependent on wind patterns, the location of traffic queues and the position and shapes of the surrounding buildings.
The research had shown that pollution hotspots tend to accumulate on the leeward side of the street (the sheltered side), in relation to the wind’s direction at roof-top level. They also revealed that the carbon monoxide levels were up to four times lower in parallel side streets, compared to the main road. “The mono oxide levels were highly variable over remarkably short distances, the junction itself showed high levels caused by queuing traffic but, with some wind patterns, these hotspots moved further down the street.
However, the leeward side of the street had consistently higher concentrations of carbon monoxide than the windward side.” said Professor Tomlin. It’s also found that pollution could be trapped within the streets emitted by re-circulating winds, but if it escapes above roof-top level it doesn’t tend to be mixed back into neighboring streets very strongly. The team says their researches has significance for local authorities and suggest other bodies monitoring air quality in urban areas.
