LIVE • 2026-09-12

Highest O3 cities right now

Top 30 cities ranked by current O3 concentration across all 217 tracked locations. Refreshes every 30 minutes. The highest O3 right now is in Monterrey, Mexico at 160.0 ppb. WHO 2021 8-hour guideline: 100 μg/m³ (~50 ppb).

#1
160.0 ppb

MX

Monterrey

111
AQI
PM2.5
6.5μg
PM10
6.9μg
O3
160.0ppb
Unhealthy for Sensitive Groups
#2
130.0 ppb

US

Chicago

54
AQI
PM2.5
9.4μg
PM10
9.6μg
O3
130.0ppb
Moderate
#3
114.0 ppb

US

New York

73
AQI
PM2.5
7.3μg
PM10
9.4μg
O3
114.0ppb
Moderate
#4
113.0 ppb

QA

Doha

98
AQI
PM2.5
38.1μg
PM10
75.0μg
O3
113.0ppb
Moderate
#5
112.0 ppb

CA

Toronto

47
AQI
PM2.5
6.5μg
PM10
6.6μg
O3
112.0ppb
Good
#6
111.0 ppb

CD

Kinshasa

155
AQI
PM2.5
62.4μg
PM10
65.7μg
O3
111.0ppb
Unhealthy
#7
109.0 ppb

SG

Singapore

100
AQI
PM2.5
46.4μg
PM10
51.9μg
O3
109.0ppb
Moderate
#8
108.0 ppb

US

Philadelphia

74
AQI
PM2.5
10.5μg
PM10
13.4μg
O3
108.0ppb
Moderate
#9
107.0 ppb

MX

Guadalajara

42
AQI
PM2.5
2.2μg
PM10
2.3μg
O3
107.0ppb
Good
#10
106.0 ppb

MX

Mexico City

74
AQI
PM2.5
9.1μg
PM10
9.3μg
O3
106.0ppb
Moderate
#11
105.0 ppb

US

Dallas

42
AQI
PM2.5
6.5μg
PM10
8.7μg
O3
105.0ppb
Good
#12
104.0 ppb

NP

Pokhara

47
AQI
PM2.5
6.9μg
PM10
6.9μg
O3
104.0ppb
Good
#13
103.0 ppb

US

Los Angeles

78
AQI
PM2.5
19.6μg
PM10
24.4μg
O3
103.0ppb
Moderate
#14
103.0 ppb

US

Boston

51
AQI
PM2.5
5.1μg
PM10
5.9μg
O3
103.0ppb
Moderate
#15
100.0 ppb

US

San Diego

55
AQI
PM2.5
11.1μg
PM10
15.9μg
O3
100.0ppb
Moderate
#16
99.0 ppb

BR

Rio de Janeiro

116
AQI
PM2.5
27.0μg
PM10
29.5μg
O3
99.0ppb
Unhealthy for Sensitive Groups
#17
99.0 ppb

US

Denver

45
AQI
PM2.5
6.0μg
PM10
7.4μg
O3
99.0ppb
Good
#18
99.0 ppb

TH

Khon Kaen

59
AQI
PM2.5
11.8μg
PM10
12.0μg
O3
99.0ppb
Moderate
#19
94.0 ppb

US

Phoenix

51
AQI
PM2.5
7.4μg
PM10
30.3μg
O3
94.0ppb
Moderate
#20
94.0 ppb

TH

Koh Samui

45
AQI
PM2.5
2.4μg
PM10
3.0μg
O3
94.0ppb
Good
#21
90.0 ppb

CL

Santiago

80
AQI
PM2.5
21.2μg
PM10
21.4μg
O3
90.0ppb
Moderate
#22
90.0 ppb

CN

Qingdao

70
AQI
PM2.5
18.2μg
PM10
24.8μg
O3
90.0ppb
Moderate
#23
90.0 ppb

CU

Havana

50
AQI
PM2.5
9.1μg
PM10
14.0μg
O3
90.0ppb
Good
#24
90.0 ppb

TH

Nakhon Ratchasima

51
AQI
PM2.5
6.9μg
PM10
7.0μg
O3
90.0ppb
Moderate
#25
89.0 ppb

PT

Lisbon

49
AQI
PM2.5
7.8μg
PM10
12.5μg
O3
89.0ppb
Good
#26
87.0 ppb

TH

Hua Hin

45
AQI
PM2.5
2.9μg
PM10
3.3μg
O3
87.0ppb
Good
#27
86.0 ppb

US

San Antonio

37
AQI
PM2.5
3.7μg
PM10
5.0μg
O3
86.0ppb
Good
#28
86.0 ppb

BR

Brasilia

48
AQI
PM2.5
4.5μg
PM10
4.6μg
O3
86.0ppb
Good
#29
86.0 ppb

BR

Manaus

64
AQI
PM2.5
13.3μg
PM10
13.9μg
O3
86.0ppb
Moderate
#30
85.0 ppb

IN

Lucknow

68
AQI
PM2.5
18.9μg
PM10
19.2μg
O3
85.0ppb
Moderate

About O3

See the full O3 guide for sources, health effects, and mitigation. Or jump back to overall most polluted cities ranked by US EPA Air Quality Index.

See also: highest PM2.5 · highest PM10 · highest NO2