Maryland Cities Ranked by Indoor Radon Levels

Measured averages from Airthings devices across Maryland, USA. Action level: 4 pCi/L — the threshold at which remediation is recommended.

Williamsport has the highest measured indoor radon in Maryland at 10.1 pCi/L, based on Airthings measurements across 201 cities.

Updated September 28, 2026

Highest city

10.1pCi/L

Williamsport

Maryland city average

2.6pCi/L

across 201 cities

Above action level

24/ 201

cities

Maryland Cities Ranked by Indoor Radon Levels
#	Location	Avg level	vs action level
1	Williamsport	10.1 pCi/L	2.5× over
2	Hancock	7.7 pCi/L	1.9× over
3	Manchester	7.5 pCi/L	1.9× over
4	Green Valley	7.4 pCi/L	1.9× over
5	Saint James	7.2 pCi/L	1.8× over
6	Boonsboro	6.1 pCi/L	1.5× over
7	Mount Airy	6.0 pCi/L	1.5× over
8	Urbana	6.0 pCi/L	1.5× over
9	Bartonsville	5.8 pCi/L	1.4× over
10	Wilson-Conococheague	5.1 pCi/L	1.3× over
11	Londontowne	4.9 pCi/L	1.2× over
12	Keedysville	4.8 pCi/L	1.2× over
13	Huntingtown	4.8 pCi/L	1.2× over
14	Walkersville	4.8 pCi/L	1.2× over
15	Westminster	4.6 pCi/L	1.1× over
16	Friendly	4.5 pCi/L	1.1× over
17	Davidsonville	4.5 pCi/L	1.1× over
18	Robinwood	4.5 pCi/L	1.1× over
19	Paramount-Long Meadow	4.4 pCi/L	1.1× over
20	Chesapeake Beach	4.3 pCi/L	1.1× over
21	Maugansville	4.3 pCi/L	1.1× over
22	Chesapeake Ranch Estates	4.2 pCi/L	1.0× over
23	Dunkirk Town Center	4.1 pCi/L	1.0× over
24	New Windsor	4.0 pCi/L	1.0× over
✓ Below EPA action level (4 pCi/L)
25	Kingsville	4.0 pCi/L	1.0× under
26	Pikesville	3.9 pCi/L	1.0× under
27	Mellwood	3.8 pCi/L	1.0× under
28	Hampstead	3.8 pCi/L	1.0× under
29	Hagerstown	3.8 pCi/L	0.9× under
30	Hughesville	3.7 pCi/L	0.9× under
31	Hunt Valley	3.7 pCi/L	0.9× under
32	Spencerville	3.7 pCi/L	0.9× under
33	Fairland	3.6 pCi/L	0.9× under
34	Oakland	3.6 pCi/L	0.9× under
35	Langley Park	3.6 pCi/L	0.9× under
36	Bel Air North	3.6 pCi/L	0.9× under
37	Naval Academy	3.6 pCi/L	0.9× under
38	Calverton	3.5 pCi/L	0.9× under
39	Crownsville	3.5 pCi/L	0.9× under
40	Huntingtown Town Center	3.5 pCi/L	0.9× under
41	Randallstown	3.5 pCi/L	0.9× under
42	Colesville	3.5 pCi/L	0.9× under
43	Ashton-Sandy Spring	3.4 pCi/L	0.9× under
44	Dunkirk	3.4 pCi/L	0.8× under
45	Cape Saint Claire	3.4 pCi/L	0.8× under
46	Elkton	3.4 pCi/L	0.8× under
47	Sykesville	3.4 pCi/L	0.8× under
48	Garrison	3.3 pCi/L	0.8× under
49	Frostburg	3.3 pCi/L	0.8× under
50	Upper Marlboro	3.3 pCi/L	0.8× under
51	Highland	3.3 pCi/L	0.8× under
52	Taneytown	3.3 pCi/L	0.8× under
53	Owings	3.2 pCi/L	0.8× under
54	Clover Hill	3.2 pCi/L	0.8× under
55	Deale	3.1 pCi/L	0.8× under
56	Damascus	3.1 pCi/L	0.8× under
57	La Plata	3.1 pCi/L	0.8× under
58	Burtonsville	3.1 pCi/L	0.8× under
59	Bel Air	3.1 pCi/L	0.8× under
60	Hillsmere Shores	3.1 pCi/L	0.8× under
61	Brunswick	3.1 pCi/L	0.8× under
62	Cumberland	3.0 pCi/L	0.8× under
63	Aberdeen	3.0 pCi/L	0.8× under
64	White Oak	3.0 pCi/L	0.7× under
65	Kemp Mill	3.0 pCi/L	0.7× under
66	Mays Chapel	3.0 pCi/L	0.7× under
67	Fort Washington	3.0 pCi/L	0.7× under
68	Lutherville	3.0 pCi/L	0.7× under
69	Adamstown	2.9 pCi/L	0.7× under
70	Eldersburg	2.9 pCi/L	0.7× under
71	Leonardtown	2.8 pCi/L	0.7× under
72	Prince Frederick	2.8 pCi/L	0.7× under
73	Rising Sun	2.8 pCi/L	0.7× under
74	Annapolis	2.8 pCi/L	0.7× under
75	Columbia	2.8 pCi/L	0.7× under
76	Linganore	2.8 pCi/L	0.7× under
77	Gambrills	2.8 pCi/L	0.7× under
78	Mechanicsville	2.6 pCi/L	0.7× under
79	Savage	2.6 pCi/L	0.7× under
80	Arnold	2.6 pCi/L	0.7× under
81	Mountain Lake Park	2.6 pCi/L	0.7× under
82	Hillandale	2.6 pCi/L	0.7× under
83	Frederick	2.6 pCi/L	0.6× under
84	Fulton	2.6 pCi/L	0.6× under
85	Owings Mills	2.5 pCi/L	0.6× under
86	Jarrettsville	2.5 pCi/L	0.6× under
87	Smithsburg	2.5 pCi/L	0.6× under
88	Darnestown	2.4 pCi/L	0.6× under
89	Rosedale	2.4 pCi/L	0.6× under
90	Bel Air South	2.4 pCi/L	0.6× under
91	Riviera Beach	2.4 pCi/L	0.6× under
92	Glenn Dale	2.4 pCi/L	0.6× under
93	Riverside	2.4 pCi/L	0.6× under
94	Catonsville	2.3 pCi/L	0.6× under
95	Reisterstown	2.3 pCi/L	0.6× under
96	North Laurel	2.3 pCi/L	0.6× under
97	Point of Rocks	2.3 pCi/L	0.6× under
98	Ellicott City	2.3 pCi/L	0.6× under
99	Myersville	2.2 pCi/L	0.6× under
100	Charlestown	2.2 pCi/L	0.5× under
101	Odenton	2.2 pCi/L	0.5× under
102	Parole	2.2 pCi/L	0.5× under
103	Potomac	2.2 pCi/L	0.5× under
104	Fallston	2.2 pCi/L	0.5× under
105	Bowie	2.2 pCi/L	0.5× under
106	California	2.2 pCi/L	0.5× under
107	Cockeysville	2.2 pCi/L	0.5× under
108	Derwood	2.1 pCi/L	0.5× under
109	Rockville	2.1 pCi/L	0.5× under
110	Germantown	2.1 pCi/L	0.5× under
111	Severna Park	2.1 pCi/L	0.5× under
112	Timonium	2.1 pCi/L	0.5× under
113	Forest Glen	2.0 pCi/L	0.5× under
114	North Beach	2.0 pCi/L	0.5× under
115	Crofton	2.0 pCi/L	0.5× under
116	North Kensington	2.0 pCi/L	0.5× under
117	Saint Charles	2.0 pCi/L	0.5× under
118	Herald Harbor	2.0 pCi/L	0.5× under
119	Chestertown	2.0 pCi/L	0.5× under
120	Brookmont	2.0 pCi/L	0.5× under
121	Carney	2.0 pCi/L	0.5× under
122	Lexington Park	2.0 pCi/L	0.5× under
123	Redland	2.0 pCi/L	0.5× under
124	South Bel Air	1.9 pCi/L	0.5× under
125	Woodlawn	1.9 pCi/L	0.5× under
126	Hyattsville	1.9 pCi/L	0.5× under
127	Jefferson	1.9 pCi/L	0.5× under
128	Clarksburg	1.9 pCi/L	0.5× under
129	Cabin John	1.9 pCi/L	0.5× under
130	Four Corners	1.9 pCi/L	0.5× under
131	Spring Ridge	1.8 pCi/L	0.5× under
132	Arden on the Severn	1.8 pCi/L	0.4× under
133	Kensington	1.8 pCi/L	0.4× under
134	Towson	1.8 pCi/L	0.4× under
135	North Potomac	1.7 pCi/L	0.4× under
136	Riva	1.7 pCi/L	0.4× under
137	Somerset	1.7 pCi/L	0.4× under
138	Ilchester	1.7 pCi/L	0.4× under
139	Jessup	1.7 pCi/L	0.4× under
140	Middletown	1.7 pCi/L	0.4× under
141	Brock Hall	1.6 pCi/L	0.4× under
142	Rossmoor	1.6 pCi/L	0.4× under
143	Perry Hall	1.6 pCi/L	0.4× under
144	Silver Spring	1.6 pCi/L	0.4× under
145	Travilah	1.6 pCi/L	0.4× under
146	Pleasant Hills	1.6 pCi/L	0.4× under
147	Chevy Chase	1.6 pCi/L	0.4× under
148	Havre de Grace	1.6 pCi/L	0.4× under
149	Wheaton	1.6 pCi/L	0.4× under
150	West Elkridge	1.6 pCi/L	0.4× under
151	Bethesda	1.5 pCi/L	0.4× under
152	Laurel	1.5 pCi/L	0.4× under
153	Montgomery Village	1.5 pCi/L	0.4× under
154	Hampton	1.5 pCi/L	0.4× under
155	Lake Shore	1.5 pCi/L	0.4× under
156	Olney	1.5 pCi/L	0.4× under
157	North Bethesda	1.5 pCi/L	0.4× under
158	Waldorf	1.5 pCi/L	0.4× under
159	South Kensington	1.4 pCi/L	0.4× under
160	Middle River	1.4 pCi/L	0.4× under
161	Friendship Village	1.4 pCi/L	0.4× under
162	Poolesville	1.4 pCi/L	0.4× under
163	Takoma Park	1.4 pCi/L	0.3× under
164	Linthicum	1.4 pCi/L	0.3× under
165	Layhill	1.4 pCi/L	0.3× under
166	White Marsh	1.4 pCi/L	0.3× under
167	Hillcrest Heights	1.4 pCi/L	0.3× under
168	Maryland City	1.3 pCi/L	0.3× under
169	North East	1.3 pCi/L	0.3× under
170	Severn	1.3 pCi/L	0.3× under
171	Brooklyn Park	1.3 pCi/L	0.3× under
172	Baltimore	1.2 pCi/L	0.3× under
173	Glenmont	1.2 pCi/L	0.3× under
174	Pasadena	1.2 pCi/L	0.3× under
175	Gaithersburg	1.2 pCi/L	0.3× under
176	South Gate	1.2 pCi/L	0.3× under
177	Chevy Chase Village	1.2 pCi/L	0.3× under
178	Ballenger Creek	1.2 pCi/L	0.3× under
179	Braddock Heights	1.2 pCi/L	0.3× under
180	Bowleys Quarters	1.1 pCi/L	0.3× under
181	Chillum	1.1 pCi/L	0.3× under
182	University Park	1.1 pCi/L	0.3× under
183	Aspen Hill	1.1 pCi/L	0.3× under
184	Cloverly	1.1 pCi/L	0.3× under
185	Oxon Hill	1.0 pCi/L	0.3× under
186	Bennsville	1.0 pCi/L	0.2× under
187	South Laurel	1.0 pCi/L	0.2× under
188	West Laurel	1.0 pCi/L	0.2× under
189	Green Haven	0.9 pCi/L	0.2× under
190	Parkville	0.9 pCi/L	0.2× under
191	Mount Rainier	0.9 pCi/L	0.2× under
192	Chester	0.8 pCi/L	0.2× under
193	Elkridge	0.8 pCi/L	0.2× under
194	Hanover	0.8 pCi/L	0.2× under
195	Glen Burnie	0.8 pCi/L	0.2× under
196	Fort Meade	0.7 pCi/L	0.2× under
197	Brandywine	0.7 pCi/L	0.2× under
198	Lansdowne	0.5 pCi/L	0.1× under
199	Milford Mill	0.5 pCi/L	0.1× under
200	College Park	0.4 pCi/L	0.1× under
201	Dundalk	0.3 pCi/L	0.1× under

See USA cities ranked by radon level See all States ranked by radon level