Radon is a chemical element; it has symbol Rn and atomic number 86. It is a radioactive noble gas and is colorless and odorless. Of the three naturally occurring radon isotopes, only radon-222 has a sufficiently long half-life for it to be released from the soil and rock, where it is generated. Radon isotopes are the immediate decay products of radium isotopes. Radon's most stable isotope, radon-222, has a half-life of only 3.8 days, making radon one of the rarest elements. Radon will be present on Earth for several billion more years, despite its short half-life, because it is constantly being produced as a step in the decay chain of uranium-238, and that of thorium-232, each of which is an extremely abundant radioactive nuclide with a half-life of several billion years. The decay of radon produces many other short-lived nuclides, known as "radon daughters", ending at stable isotopes of lead. Radon-222 occurs in significant quantities as a step in the normal radioactive decay chain of uranium-238, also known as the uranium series, which slowly decays into a variety of radioactive nuclides and eventually decays into lead-206, which is stable. Radon-220 occurs in minute quantities as an intermediate step in the decay chain of thorium-232, also known as the thorium series, which eventually decays into lead-208, which is stable.
Indoor air quality (IAQ) is the air quality within and around buildings and structures. Poor indoor air quality due to indoor air pollution is known to affect the health, comfort, and well-being of building occupants. It has also been linked to sick building syndrome, reduced productivity, and impaired learning in schools. Common pollutants of indoor air include: secondhand tobacco smoke, air pollutants from indoor combustion, radon, molds and other allergens, carbon monoxide, volatile organic compounds, legionella and other bacteria, asbestos fibers, carbon dioxide, ozone and particulates. Source control, filtration, and the use of ventilation to dilute contaminants are the primary methods for improving indoor air quality.
Radium Hot Springs, informally and commonly called Radium, is a village of 1,339 residents in the East Kootenay region of British Columbia. The village is named for the hot springs in the nearby Kootenay National Park. From Banff, Alberta, it is accessible via Highway 93.
The Tehran Metro is a rapid transit system serving Tehran, the capital of Iran. It is the largest metro system in the Middle East. The system is owned and operated by Tehran Urban and Suburban Railway. It consists of six operational metro lines, with construction under way on five lines including northwestern extension of line 4, south extension line 6, northwestern and east extension line 7 and Line 10 and Line 8.
Radon mitigation is any process used to reduce radon gas concentrations in the breathing zones of occupied buildings, or radon from water supplies. Radon is a significant contributor to environmental radioactivity and can cause serious health problems such as lung cancer.
Krypton-85 (85Kr) is a radioisotope of krypton.
Radium and radon are important contributors to environmental radioactivity. Radon occurs naturally as a result of decay of radioactive elements in soil and it can accumulate in houses built on areas where such decay occurs. Radon is a major cause of cancer; it is estimated to contribute to ~2% of all cancer related deaths in Europe.
The Imam Khomeini metro station is the junction of Tehran Metro Line 1 and Line 2. The station was opened on 21 February 2000, it is located in Imam Khomeini Square between Panzdah-e-Khordad Metro Station and Saadi Metro Station in Line 1 and Mellat Metro Station and Hasan Abad Metro Station in Line 2.
Mirdamad Metro Station is a station in Tehran Metro Line 1, located next to Mirdamad Boulevard. It was opened on 19 May 2009. The station has an outdoor parking facility for commuters.
Doctor Shariati Metro Station is a station in Tehran Metro Line 1. It is located in Shariati Street. It is between Mirdamad Metro Station and Gholhak Metro Station. It was opened on 19 May 2009.
Gholhak Metro Station is a station of Tehran Metro Line 1. It is located in Shariati Street in Gholhak neighborhood. The neighboring stations are Shariati and Shahid Sadr. It was opened on 19 May 2009.
Ferdowsi Metro Station is a station in Tehran Metro Line 4. It is located in Ferdowsi Square the junction of Enghelab Street and Ferdowsi Street. It is between Darvaze Dolat Metro Station and Teatr-e Shahr Metro Station. It has connection to Tehran Bus BRT1.
Tehran (Sadeghiyeh) Metro Station is the junction of Tehran Metro Line 2 and Tehran Metro Line 5. It is located in Sadeghiye neighborhood near Mohammad Ali Jenah Expressway and Tehran-Karaj Freeway. It is the west end of Line 2 and the east end of Line 5. The next station in Line 2 is Tarasht Metro Station and the next station in Line 5 is Eram-e Sabz Metro Station. It also has a big parking lot and is considered as the most crowded Tehran metro station. It is currently the only above ground station on Tehran Metro Line 2.
Karaj Metro Station is a station in Tehran Metro Line 5. It is located in southeastern Karaj near Tehran-Qazvin Freeway. It is between Atmosfer Metro Station and Mahdasht Metro Station. The station is 1.8 km (1.1 mi) north of Karaj railway Station, which serves Tehran Commuter Railway.
The health effects of radon are harmful, and include an increased chance of lung cancer. Radon is a radioactive, colorless, odorless, tasteless noble gas, which has been studied by a number of scientific and medical bodies for its effects on health. A naturally-occurring gas formed as a decay product of radium, radon is one of the densest substances that remains a gas under normal conditions, and is considered to be a health hazard due to its radioactivity. Its most stable isotope, radon-222, has a half-life of 3.8 days. Due to its high radioactivity, it has been less well studied by chemists, but a few compounds are known.
Farhangsara Metro Station is the eastern end of Tehran Metro Line 2, in Iran. It was opened in 2010, with Mohammad-Bagher Ghalibaf attending the inauguration. It is located in Jashnvareh Street in Tehranpars neighborhood. The next station is Tehran Pars Metro Station.
Rahahan Metro Station is a metro station in line3 of Tehran metro, located in Rahahan Square. As suggested by the name, it is connected with Tehran Railway Station
Working level (WL) is a historical unit of concentration of radioactive decay products of radon, applied to uranium mining environment. One working level refers to the concentration of short-lived decay products of radon in equilibrium with 3,700 Bq/m3 (100 pCi/L) in air. These decay products would emit 1.3 × 105 MeV in complete decay. The Nuclear Regulatory Commission uses this definition.
Hossein Abad Metro Station is a metro train station in line 3 of the Tehran Metro. It is located on Mozhdeh Street at Hossein Abad neighbourhood in Northwestern Tehran.
Tetra Cave Natural Monument is a karst cave 1.6 km northwest of Tskaltubo in Tskaltubo Municipality in Imereti region of Georgia. Locally known as White Cave it is located 140 meters above sea level.
Chubtarash Street- 
