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 196 cities.

Updated August 30, 2026

Highest city

10.1pCi/L

Williamsport

Maryland city average

2.6pCi/L

across 196 cities

Above action level

25/ 196

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	8.6 pCi/L	2.1× over
3	Green Valley	7.6 pCi/L	1.9× over
4	Manchester	7.5 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	6.1 pCi/L	1.5× over
8	Urbana	6.0 pCi/L	1.5× over
9	Bartonsville	5.8 pCi/L	1.4× over
10	Huntingtown	5.2 pCi/L	1.3× over
11	Wilson-Conococheague	5.1 pCi/L	1.3× over
12	Walkersville	5.0 pCi/L	1.3× over
13	Londontowne	4.9 pCi/L	1.2× over
14	Keedysville	4.8 pCi/L	1.2× over
15	Paramount-Long Meadow	4.7 pCi/L	1.2× over
16	Westminster	4.6 pCi/L	1.1× over
17	Friendly	4.5 pCi/L	1.1× over
18	Robinwood	4.5 pCi/L	1.1× over
19	Dunkirk Town Center	4.5 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	Davidsonville	4.2 pCi/L	1.0× over
24	New Windsor	4.0 pCi/L	1.0× over
25	Kingsville	4.0 pCi/L	1.0× over
✓ Below EPA action level (4 pCi/L)
26	Pikesville	4.0 pCi/L	1.0× under
27	Hagerstown	3.9 pCi/L	1.0× under
28	Mellwood	3.8 pCi/L	1.0× under
29	Hampstead	3.8 pCi/L	1.0× under
30	Hughesville	3.7 pCi/L	0.9× under
31	Bel Air North	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	Naval Academy	3.6 pCi/L	0.9× under
37	Calverton	3.5 pCi/L	0.9× under
38	Crownsville	3.5 pCi/L	0.9× under
39	Hunt Valley	3.5 pCi/L	0.9× under
40	Randallstown	3.5 pCi/L	0.9× under
41	Colesville	3.5 pCi/L	0.9× under
42	Upper Marlboro	3.4 pCi/L	0.9× under
43	Ashton-Sandy Spring	3.4 pCi/L	0.9× under
44	Owings	3.4 pCi/L	0.9× under
45	Sykesville	3.4 pCi/L	0.9× under
46	Dunkirk	3.4 pCi/L	0.8× under
47	Cape Saint Claire	3.4 pCi/L	0.8× under
48	Elkton	3.4 pCi/L	0.8× under
49	Garrison	3.3 pCi/L	0.8× under
50	Frostburg	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	Huntingtown Town Center	3.2 pCi/L	0.8× under
54	Hillsmere Shores	3.2 pCi/L	0.8× under
55	La Plata	3.2 pCi/L	0.8× under
56	Burtonsville	3.2 pCi/L	0.8× under
57	Cumberland	3.1 pCi/L	0.8× under
58	Deale	3.1 pCi/L	0.8× under
59	Damascus	3.1 pCi/L	0.8× under
60	Bel Air	3.1 pCi/L	0.8× under
61	Brunswick	3.1 pCi/L	0.8× under
62	Clover Hill	3.0 pCi/L	0.8× under
63	Mays Chapel	3.0 pCi/L	0.8× under
64	Aberdeen	3.0 pCi/L	0.8× under
65	Kemp Mill	3.0 pCi/L	0.7× under
66	Lutherville	3.0 pCi/L	0.7× under
67	Fort Washington	3.0 pCi/L	0.7× under
68	Annapolis	2.9 pCi/L	0.7× under
69	White Oak	2.9 pCi/L	0.7× under
70	Adamstown	2.9 pCi/L	0.7× under
71	Eldersburg	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	Linganore	2.8 pCi/L	0.7× under
75	Columbia	2.8 pCi/L	0.7× under
76	Leonardtown	2.8 pCi/L	0.7× under
77	Gambrills	2.8 pCi/L	0.7× under
78	Arnold	2.7 pCi/L	0.7× under
79	Mechanicsville	2.6 pCi/L	0.7× under
80	Fulton	2.6 pCi/L	0.7× under
81	Frederick	2.6 pCi/L	0.7× under
82	Mountain Lake Park	2.6 pCi/L	0.7× under
83	Savage	2.6 pCi/L	0.7× under
84	Hillandale	2.6 pCi/L	0.7× under
85	Jarrettsville	2.6 pCi/L	0.6× under
86	Owings Mills	2.5 pCi/L	0.6× under
87	Darnestown	2.5 pCi/L	0.6× under
88	Smithsburg	2.5 pCi/L	0.6× under
89	Riverside	2.4 pCi/L	0.6× under
90	Rosedale	2.4 pCi/L	0.6× under
91	Bel Air South	2.4 pCi/L	0.6× under
92	Riviera Beach	2.4 pCi/L	0.6× under
93	Glenn Dale	2.4 pCi/L	0.6× under
94	Reisterstown	2.4 pCi/L	0.6× under
95	Catonsville	2.3 pCi/L	0.6× under
96	Ellicott City	2.3 pCi/L	0.6× under
97	North Laurel	2.3 pCi/L	0.6× under
98	Point of Rocks	2.3 pCi/L	0.6× under
99	Myersville	2.2 pCi/L	0.6× under
100	Saint Charles	2.2 pCi/L	0.6× under
101	Odenton	2.2 pCi/L	0.5× under
102	North East	2.2 pCi/L	0.5× under
103	Parole	2.2 pCi/L	0.5× under
104	Potomac	2.2 pCi/L	0.5× under
105	Rockville	2.2 pCi/L	0.5× under
106	Bowie	2.2 pCi/L	0.5× under
107	California	2.2 pCi/L	0.5× under
108	Cockeysville	2.2 pCi/L	0.5× under
109	Fallston	2.1 pCi/L	0.5× under
110	Severna Park	2.1 pCi/L	0.5× under
111	Germantown	2.1 pCi/L	0.5× under
112	Forest Glen	2.1 pCi/L	0.5× under
113	Crofton	2.0 pCi/L	0.5× under
114	North Kensington	2.0 pCi/L	0.5× under
115	Timonium	2.0 pCi/L	0.5× under
116	Hyattsville	2.0 pCi/L	0.5× under
117	Derwood	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	Clarksburg	1.9 pCi/L	0.5× under
126	Jefferson	1.9 pCi/L	0.5× under
127	Four Corners	1.9 pCi/L	0.5× under
128	Cabin John	1.9 pCi/L	0.5× under
129	Kensington	1.8 pCi/L	0.4× under
130	Towson	1.8 pCi/L	0.4× under
131	North Potomac	1.8 pCi/L	0.4× under
132	Arden on the Severn	1.8 pCi/L	0.4× under
133	Spring Ridge	1.8 pCi/L	0.4× under
134	Ilchester	1.7 pCi/L	0.4× under
135	Somerset	1.7 pCi/L	0.4× under
136	Middletown	1.7 pCi/L	0.4× under
137	Rossmoor	1.7 pCi/L	0.4× under
138	Jessup	1.7 pCi/L	0.4× under
139	Brock Hall	1.6 pCi/L	0.4× under
140	Charlestown	1.6 pCi/L	0.4× under
141	Perry Hall	1.6 pCi/L	0.4× under
142	Chevy Chase	1.6 pCi/L	0.4× under
143	Travilah	1.6 pCi/L	0.4× under
144	Havre de Grace	1.6 pCi/L	0.4× under
145	Riva	1.6 pCi/L	0.4× under
146	Wheaton	1.6 pCi/L	0.4× under
147	West Elkridge	1.6 pCi/L	0.4× under
148	Bethesda	1.5 pCi/L	0.4× under
149	South Kensington	1.5 pCi/L	0.4× under
150	Montgomery Village	1.5 pCi/L	0.4× under
151	Poolesville	1.5 pCi/L	0.4× under
152	Silver Spring	1.5 pCi/L	0.4× under
153	Hampton	1.5 pCi/L	0.4× under
154	Laurel	1.5 pCi/L	0.4× under
155	Takoma Park	1.5 pCi/L	0.4× under
156	Olney	1.5 pCi/L	0.4× under
157	Friendship Village	1.5 pCi/L	0.4× under
158	North Bethesda	1.5 pCi/L	0.4× under
159	Waldorf	1.5 pCi/L	0.4× under
160	Layhill	1.4 pCi/L	0.4× under
161	Linthicum	1.4 pCi/L	0.3× under
162	White Marsh	1.4 pCi/L	0.3× under
163	Lake Shore	1.3 pCi/L	0.3× under
164	Severn	1.3 pCi/L	0.3× under
165	Brooklyn Park	1.3 pCi/L	0.3× under
166	Baltimore	1.2 pCi/L	0.3× under
167	Glenmont	1.2 pCi/L	0.3× under
168	Gaithersburg	1.2 pCi/L	0.3× under
169	South Gate	1.2 pCi/L	0.3× under
170	Chevy Chase Village	1.2 pCi/L	0.3× under
171	Hillcrest Heights	1.2 pCi/L	0.3× under
172	Ballenger Creek	1.2 pCi/L	0.3× under
173	Maryland City	1.2 pCi/L	0.3× under
174	Braddock Heights	1.2 pCi/L	0.3× under
175	Chillum	1.1 pCi/L	0.3× under
176	Pasadena	1.1 pCi/L	0.3× under
177	South Laurel	1.1 pCi/L	0.3× under
178	University Park	1.1 pCi/L	0.3× under
179	Aspen Hill	1.1 pCi/L	0.3× under
180	Cloverly	1.1 pCi/L	0.3× under
181	Oxon Hill	1.0 pCi/L	0.3× under
182	Bennsville	1.0 pCi/L	0.2× under
183	West Laurel	1.0 pCi/L	0.2× under
184	Green Haven	0.9 pCi/L	0.2× under
185	Parkville	0.9 pCi/L	0.2× under
186	Mount Rainier	0.9 pCi/L	0.2× under
187	Chester	0.8 pCi/L	0.2× under
188	Elkridge	0.8 pCi/L	0.2× under
189	Glen Burnie	0.8 pCi/L	0.2× under
190	Hanover	0.8 pCi/L	0.2× under
191	Fort Meade	0.7 pCi/L	0.2× under
192	Brandywine	0.7 pCi/L	0.2× under
193	Lansdowne	0.5 pCi/L	0.1× under
194	Milford Mill	0.4 pCi/L	0.1× under
195	College Park	0.4 pCi/L	0.1× under
196	Dundalk	0.3 pCi/L	0.1× under

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