Table 2 Annual mean levels for five air pollutants measured at Secunda Club Station (Sasol) for 2005–2019 (NAAQS exceedances highlighted in bold font; years without data or years that did not pass the data completeness threshold of 75% denoted with “--“)

Pollutant

NAAQS limit

2005

2006

2007

2008

2009

PM_2.5

20 μg/m³

–

–

–

–

–

PM₁₀

40 μg/m³

38

35

39

37

–

SO₂

19 ppb

9

8

6

–

8

NO₂

21 ppb

7

–

11

11

8

Pollutant

NAAQS limit

2010

2011

2012

2013

2014

PM_2.5

20 μg/m³

–

–

13

13

15

PM₁₀

40 μg/m³

30

28

30

33

45

SO₂

19 ppb

7

7

8

7

9

NO₂

21 ppb

10

10

9

11

14

Pollutant

NAAQS limit

2015

2016

2017

2018

2019

PM_2.5

20 μg/m³

–

16

–

–

–

PM₁₀

40 μg/m³

–

38

–

–

–

SO₂

19 ppb

7

8

–

–

–

NO₂

21 ppb

11

9

–

–

–