However, the first two are now preventable with vaccines. Some biologic pollutants, such as measles, chickenpox, and influenza are transmitted through the air. These biologic pollutants can be related to some serious health effects. Indoor pollutants can be placed into two groups, biologic and chemical.īiologic pollutants include bacteria, molds, viruses, animal dander, cat saliva, dust mites, cockroaches, and pollen. In addition, high temperature and humidity levels can increase the concentration of some pollutants.
Air pollutant levels in the home increase if not enough outdoor air is brought in to dilute emissions from indoor sources and to carry indoor air pollutants out of the home. Numerous forms of indoor air pollution are possible in the modern home. Such groups include the young, the elderly, and the chronically ill, especially those suffering from respiratory or cardiovascular disease. In addition, people exposed to indoor air pollutants for the longest periods are often those most susceptible to their effects. Thus, for many people, the risks to health from exposure to indoor air pollution may be greater than risks from outdoor pollution. Other research indicates that people spend approximately 90% of their time indoors. In the last several years, a growing body of scientific evidence has indicated that the air within homes and other buildings can be more seriously polluted than the outdoor air in even the largest and most industrialized cities.
Indoor air pollution and exposure to hazardous substances in the home are risks we can do something about. Some are risks we might decide to avoid if we had the opportunity to make informed choices. Some we choose to accept because to do otherwise would restrict our ability to lead our lives the way we want.
Driving in cars, flying in airplanes, engaging in recreational activities, and being exposed to environmental pollutants all pose varying degrees of risk. We all face a variety of risks to our health as we go about our day-to-day lives. “Walking into a modern building can sometimes be compared to placing your head inside a plastic bag that is filled with toxic fumes.”
#The Last Hours Of Ancient Sunlight Pdf manual#
And just like that, a man 2200 years ago found the circumference of our entire planet with just a stick and his brain.Download Adobe Acrobat version of the manual Cdc-pdf He could then use simple proportions to find the Earth's circumference - 7.2 degrees is 1/50 of 360 degrees, so 800 times 50 equals 40,000 kilometers. Eratosthenes hired a man to pace the distance between the two cities and learned they were 5,000 stadia apart, which is about 800 kilometers. Since the difference in shadow length is 7 degrees in Alexandria and Syene, that means the two cities are 7 degrees apart on Earth's 360-degrees surface. If the Earth really was a sphere, Eratosthenes could use his observations to estimate the circumference of the entire planet. The idea of a spherical Earth was floated around by Pythagoras around 500 BC and validated by Aristotle a couple centuries later. And Eratosthenes probably already knew that. Now, if the sun's rays are coming in at the same angle at the same time of day, and a stick in Alexandria is casting a shadow while a stick in Syene is not, it must mean that the Earth's surface is curved.
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