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The largest natural contributor to public radiation dose is radon, a naturally occurring, radioactive gas found in soil and rock. [10] If the gas is inhaled, some of the radon particles may attach to the inner lining of the lung. These particles continue to decay, emitting alpha particles, which can damage cells in the lung tissue. [11]
The number of unstable nuclides discovered has grown, with about 3000 known in 2006. [55] The most common and consequently historically the most important forms of natural radioactive decay involve the emission of alpha-particles, beta-particles, and gamma rays.
Atmospheric particulate matter, also known as particulate matter, or PM, describes solids and/or liquid particles suspended in a gas, most commonly the Earth's atmosphere. [1] Particles in the atmosphere can be divided into two types, depending on the way they are emitted. Primary particles, such as mineral dust, are emitted into the atmosphere ...
Particulates or atmospheric particulate matter (see below for other names) are microscopic particles of solid or liquid matter suspended in the air.The term aerosol refers to the particulate/air mixture, as opposed to the particulate matter alone, [1] though it is sometimes defined as a subset of aerosol terminology. [2]
Inside protons and neutrons, there are fundamental particles called quarks. The two most common types of quarks are up quarks, which have a charge of + 2 ⁄ 3, and down quarks, with a − 1 ⁄ 3 charge. Quarks arrange themselves in sets of three such that they make protons and neutrons.
Dust is made of fine particles of solid matter. [1] On Earth, it generally consists of particles in the atmosphere that come from various sources such as soil lifted by wind (an aeolian process), volcanic eruptions, and pollution. Dust in homes is composed of about 20–50% dead skin cells. [2]
DEET is often sold and used in spray or lotion in concentrations up to 100%. [10] Consumer Reports found a correlation between DEET concentration and hours of protection against insect bites. 100% DEET was found to offer up to 12 hours of protection while several lower concentration DEET formulations (20–34%) offered 3–6 hours of protection.
Many species live most of their lives as single cells or are filamentous, while others form colonies made up from long chains of cells, or are highly differentiated macroscopic seaweeds. Red algae , a (disputed) phylum contains about 7,000 recognised species, [ 146 ] mostly multicellular and including many notable seaweeds.