<\/p>\n\n\n
Boston has some of the oldest housing stock in the country. That history is part of the city\u2019s charm\u2014but it also creates an easy-to-miss gap with modern indoor-air issues like radon, especially in older rentals and multi-family buildings across Greater Boston.<\/span><\/p>\n In many triple-deckers, brownstones, and pre-war apartment buildings\u2014from Cambridge and Somerville to Brookline, Medford, Newton, Quincy, and Waltham\u2014basements and lower levels aren\u2019t \u201cunused space.\u201d They\u2019re where people do laundry, store strollers and bikes, swap seasonal bins, check the boiler, or carve out a small home gym or work area. Garden-level apartments are common, too, and they\u2019re often marketed as convenient and affordable without much discussion of what \u201cclosest to the ground\u201d can mean for radon testing.<\/span><\/p>\n That\u2019s the central knowledge gap in radon risk Boston MA: not that every building is high, but that older foundations and rental turnover can keep radon off the checklist. People assume \u201cradon is a suburban problem,\u201d or that an older, draftier building can\u2019t have radon. In reality, results can differ dramatically from one building to the next\u2014even among similar-looking homes on the same block in Somerville or a quiet side street in Brookline. The practical approach stays consistent: know when to test, test correctly, and mitigate when results call for it.<\/span><\/p>\n Radon is a naturally occurring radioactive gas that forms in soil and rock and can enter buildings through openings and gaps in the foundation. You can\u2019t see or smell it, which is why it often gets overlooked during a renovation, a unit turnover, or even a routine safety conversation.<\/span><\/p>\n The main concern is long-term exposure. The EPA says any radon carries some risk, and the EPA \u201caction level\u201d is 4.0 pCi\/L\u2014meaning mitigation is generally recommended at or above that level. Many health organizations also encourage considering mitigation for results between 2.0 and 4.0 pCi\/L, especially when people spend a lot of time on lower levels.<\/span><\/p>\n The most useful local takeaway for Greater Boston isn\u2019t a blanket label like \u201cBoston is high\u201d or \u201cBoston is low.\u201d It\u2019s that radon can be highly variable in the metro area:<\/span><\/p>\n So yes\u2014Cambridge, Somerville, Brookline, Quincy, Medford, Newton, and Waltham can all include homes that test low and others nearby that test higher. In practice, \u201clocal radon knowledge\u201d comes from testing the specific building (and the right level), not assumptions based on zip code.<\/span><\/p>\n For local resources and guidance across communities, you can also browse: <\/span>Boston<\/span><\/a> and <\/span>Massachusetts Radon Mitigation<\/span><\/a>.<\/span><\/p>\n Older Boston-area buildings tend to have features that make radon pathways harder to predict and easier to ignore\u2014especially when a basement is treated as a utility zone rather than living space.<\/span><\/p>\n Common conditions in older housing stock include:<\/span><\/p>\n Where the Greater Boston angle really matters is how these basements are used day to day. In a Newton single-family or a Waltham two-family, the basement might be \u201cjust storage,\u201d but it\u2019s still the place people return to regularly for laundry, tools, holiday bins, or a quick workout. In Cambridge, Somerville, and Brookline, it\u2019s common for residents to pass through basement entries, use bike rooms, or spend time in garden units that sit partly below grade.<\/span><\/p>\n Radon risk is often highest on the lowest occupied level because that\u2019s where soil gas entry is most direct. In multi-family buildings\u2014including triple-deckers and older apartment houses\u2014this is why a garden unit can have a different radon profile than a third-floor unit, even when they share the same address and the same landlord.<\/span><\/p>\n RadonResources.com user-submitted radon tests in the <\/span>Boston, MA area<\/b> show a pattern residents should take seriously: across <\/span>15<\/b> submissions from the metro and nearby communities, the <\/span>average reported level is 5.9 pCi\/L<\/b> (median <\/span>5.0 pCi\/L<\/b>). Importantly, <\/span>80%<\/b> of submissions are <\/span>at or above 4.0 pCi\/L<\/b> (the EPA action guideline), and <\/span>13%<\/b> are <\/span>10 pCi\/L or higher<\/b>. The highest submitted reading in this dataset for the metro is <\/span>19 pCi\/L<\/b>. Because radon can vary dramatically from one house to the next\u2014even on the same street\u2014the takeaway isn\u2019t to guess; it\u2019s to <\/span>test your specific home<\/b>, especially if you have a basement, garden unit, crawlspace, or spend a lot of time on the lowest level.<\/span><\/p>\n If you\u2019re searching for \u201cGreater Boston radon levels,\u201d it helps to treat any map or regional summary as a starting point, not a prediction. Older buildings and rentals add another layer of uncertainty: two similar properties\u2014say, one in Medford and one in Quincy\u2014can behave differently based on foundation condition, air sealing, and how lower levels are used.<\/span><\/p>\n Why variability is especially relevant in the Boston metro:<\/span><\/p>\n1. Radon risk across Greater Boston<\/span><\/h2>\n
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2. Older foundations and basements<\/span><\/h2>\n
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3. Radon Levels in the Greater Boston Area and Surrounding Communities<\/span><\/h2>\n
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\n City<\/b><\/td>\n Submissions<\/b><\/td>\n Avg pCi\/L<\/b><\/td>\n Median pCi\/L<\/b><\/td>\n % \u2265 4.0<\/b><\/td>\n Max<\/b><\/td>\n<\/tr>\n \n Medford, MA<\/span><\/a><\/td>\n 3<\/span><\/td>\n 8.0<\/span><\/td>\n 5.0<\/span><\/td>\n 100%<\/span><\/td>\n 15<\/span><\/td>\n<\/tr>\n \n Somerville, MA<\/span><\/a><\/td>\n 3<\/span><\/td>\n 4.3<\/span><\/td>\n 5.0<\/span><\/td>\n 67%<\/span><\/td>\n 6<\/span><\/td>\n<\/tr>\n \n Quincy, MA<\/span><\/a><\/td>\n 2<\/span><\/td>\n 10.5<\/span><\/td>\n 10.5<\/span><\/td>\n 50%<\/span><\/td>\n 19<\/span><\/td>\n<\/tr>\n \n Malden, MA<\/span><\/a><\/td>\n 2<\/span><\/td>\n 5.0<\/span><\/td>\n 5.0<\/span><\/td>\n 100%<\/span><\/td>\n 5<\/span><\/td>\n<\/tr>\n \n Arlington, MA<\/span><\/a><\/td>\n 2<\/span><\/td>\n 4.0<\/span><\/td>\n 4.0<\/span><\/td>\n 50%<\/span><\/td>\n 5<\/span><\/td>\n<\/tr>\n \n Cambridge, MA<\/span><\/a><\/td>\n 1<\/span><\/td>\n 5.0<\/span><\/td>\n 5.0<\/span><\/td>\n 100%<\/span><\/td>\n 5<\/span><\/td>\n<\/tr>\n \n Everett, MA<\/span><\/a><\/td>\n 1<\/span><\/td>\n 4.0<\/span><\/td>\n 4.0<\/span><\/td>\n 100%<\/span><\/td>\n 4<\/span><\/td>\n<\/tr>\n \n Waltham, MA<\/span><\/a><\/td>\n 1<\/span><\/td>\n 4.0<\/span><\/td>\n 4.0<\/span><\/td>\n 100%<\/span><\/td>\n 4<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n \n