Horley, Surrey, United Kingdom Historical Air Quality Analysis
Dive into detailed Air Quality Insights with historical data, monthly patterns, and yearly trends at your fingertips!
September Air Quality Analysis
Horley, Surrey, United Kingdom
AQI Trends: Highest and Lowest
Same Day Analysis (20th September ):
On this day, AQI across the 3 years varied significantly: 2025 ranks 1st highest AQI at 38 of Good air quality on the same day.
Download 2024 Annual Data
World Air Quality Report

Day & Night AQI Trend: 20th Sep - 21st Sep 2025
Horley, Surrey, United Kingdom
6 AM20th Sep 2025
7 PM
5 AM21st Sep 2025
56AQI
33AQI
36AQI
19AQI
In the last 24 hours,
Horley's AQI reached its highest point of 56 at 9 AM during the Day, while the lowest point, 19, was recorded at 5 AM during the Night between 20th Sep and 21st Sep 2025.
Day & Night AQI Trend : Aug - Sep 2025
Horley, Surrey, United Kingdom
16°C10/23°C
17°C13/23°C
18°C14/23°C
20°C13/26°C
19°C15/25°C
17°C13/22°C
16°C11/21°C
16°C13/20°C
16°C12/21°C
16°C13/20°C
16°C13/20°C
15°C12/18°C
17°C14/19°C
15°C12/19°C
15°C11/21°C
18°C12/23°C
19°C15/23°C
15°C11/20°C
15°C11/20°C
15°C12/18°C
14°C11/18°C
14°C10/17°C
13°C10/16°C
14°C9/17°C
15°C13/18°C
14°C11/18°C
16°C12/18°C
18°C15/21°C
18°C14/23°C
15°C10/20°C
--°C/°C
28AQI
24AQI
26AQI
23AQI
2025 Days Vs Air Quality
Horley, Surrey, United Kingdom
73%
192
27%
70
0.3%
1
Total number of days with different AQI categories in last 264 days in 2025 (101 days remaining)
Under WHO’s Safe Air Quality Limits: 73%
Health Risk Level:
Low
In 2025, 73% of 264 days were within WHO’s safe air quality limits. The risk of health issues is Low, but the long-term effects, especially on vulnerable individuals, remain uncertain.
Annual Air Quality Insights
Horley, Surrey, United Kingdom
AQI levels in 2025
Jan.
Feb.
Mar.
Apr.
May
Jun.
Jul.
Aug.
Sep.
Oct.
Nov.
Dec.
31AQI
31AQI
47AQI
58AQI
33AQI
24AQI
23AQI
44AQI
49AQI
59AQI
89AQI
85AQI
63AQI
61AQI
62AQI
58AQI
58AQI
71AQI
69AQI
62AQI
70AQI
76AQI
58AQI
41AQI
40AQI
41AQI
32AQI
32AQI
31AQI
38AQI
39AQI
42AQI
60AQI
72AQI
43AQI
45AQI
56AQI
44AQI
72AQI
54AQI
94AQI
82AQI
72AQI
73AQI
65AQI
100AQI
72AQI
69AQI
75AQI
82AQI
61AQI
39AQI
50AQI
44AQI
29AQI
39AQI
34AQI
30AQI
50AQI
52AQI
61AQI
76AQI
78AQI
96AQI
86AQI
54AQI
56AQI
85AQI
133AQI
87AQI
39AQI
34AQI
43AQI
32AQI
33AQI
31AQI
49AQI
65AQI
56AQI
61AQI
48AQI
52AQI
86AQI
94AQI
58AQI
51AQI
39AQI
35AQI
39AQI
39AQI
39AQI
46AQI
58AQI
74AQI
52AQI
36AQI
35AQI
51AQI
50AQI
40AQI
58AQI
69AQI
50AQI
30AQI
48AQI
26AQI
32AQI
39AQI
46AQI
34AQI
55AQI
29AQI
25AQI
46AQI
52AQI
58AQI
70AQI
56AQI
57AQI
58AQI
68AQI
56AQI
51AQI
25AQI
26AQI
23AQI
26AQI
28AQI
37AQI
35AQI
37AQI
32AQI
41AQI
37AQI
38AQI
43AQI
36AQI
46AQI
41AQI
33AQI
38AQI
36AQI
32AQI
33AQI
21AQI
25AQI
24AQI
22AQI
25AQI
26AQI
28AQI
28AQI
24AQI
29AQI
22AQI
22AQI
19AQI
18AQI
22AQI
51AQI
49AQI
42AQI
48AQI
41AQI
42AQI
33AQI
30AQI
30AQI
35AQI
44AQI
46AQI
43AQI
38AQI
29AQI
28AQI
24AQI
24AQI
26AQI
20AQI
23AQI
32AQI
40AQI
39AQI
23AQI
23AQI
23AQI
21AQI
24AQI
26AQI
28AQI
28AQI
32AQI
30AQI
32AQI
34AQI
25AQI
24AQI
24AQI
27AQI
31AQI
26AQI
20AQI
18AQI
23AQI
41AQI
40AQI
41AQI
27AQI
29AQI
31AQI
35AQI
30AQI
23AQI
21AQI
24AQI
25AQI
23AQI
27AQI
28AQI
31AQI
23AQI
40AQI
52AQI
51AQI
57AQI
53AQI
39AQI
44AQI
37AQI
31AQI
31AQI
31AQI
30AQI
26AQI
25AQI
29AQI
32AQI
32AQI
29AQI
27AQI
23AQI
22AQI
23AQI
24AQI
22AQI
22AQI
28AQI
21AQI
24AQI
24AQI
23AQI
24AQI
23AQI
22AQI
20AQI
18AQI
18AQI
26AQI
26AQI
23AQI
21AQI
29AQI
38AQI
51AQI
59AQI
60AQI
47AQI
34AQI
32AQI
29AQI
32AQI
24AQI
No. of days
202541AQI
Highest AQI recorded in
March60AQI
Lowest AQI recorded in
September24AQI
202434AQI
Highest AQI recorded in
March57AQI
Lowest AQI recorded in
April21AQI
202334AQI
Highest AQI recorded in
February71AQI
Lowest AQI recorded in
October26AQI
202231AQI
Highest AQI recorded in
December55AQI
Lowest AQI recorded in
October11AQI
Most & Least Polluted Years Over the Last 4 Years
Horley's annual 2025 AQI (41) shows an average percentage change of 25.9% (worsened AQI) compared to previous years: 2022 (31), 2023 (34), 2024 (34).