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Key findings - Nitrogen dioxide

Current situation

In 2008, all sites in New Zealand monitoring nitrogen dioxide met the 1-hour national standard and the 24-hour national guideline.

The Auckland (Queen Street) site was the only site not to meet the annual WHO guideline.

The Auckland and Wellington monitoring sites, the results of which are shown in figures 4, 5 and 6, are located close to industry and/or major roads. These types of locations are the most likely to be affected by elevated levels of nitrogen dioxide. The Christchurch monitoring site is located in a residential area.

Similarly, shorter monitoring surveys conducted at peak traffic locations in the Hawke’s Bay region in 2008 reported that nitrogen dioxide levels at these locations were well below the 1-hour standard and the 24-hour guideline.8

Figure 4: Maximum nitrogen dioxide levels, 1-hour average, 1988–2008

Figure 4: Maximum nitrogen dioxide levels, 1-hour average, 1988–2008

Source: Auckland Regional Council,9 Environment Canterbury,0 Greater Wellington.12

Note: Due to some data limitations the 2007 and 2008 values for Christchurch may not reflect the maximum concentration experienced at this site.

Year Auckland (Penrose)
(µg/m3)
Auckland (Khyber Pass Road) (µg/m3) Auckland (Queen Street) (µg/m3) Wellington (Central) (µg/m3) Christchurch(St Albans)
(µg/m3)
1988         194
1989         238
1990 102       412
1991 65       228
1992 148       162
1993 128       124
1994 67       85
1995 83       132
1996 114       200
1997 97       119
1998 155 418     93
1999 117 246     112
2000 170 434     108
2001 311 277     106
2002 124 250     117
2003 74 239     120
2004 99 271 227   154
2005 236 264 337 138 77
2006 101 171 213 142 115
2007 88 147 281 103 81
2008 110 161 169 101 60

Figure 5: Maximum nitrogen dioxide levels, 24-hour average, 1988–2008

Figure 5: Maximum nitrogen dioxide levels, 24-hour average, 1988–2008

Source: Auckland Regional Council,9 Environment Canterbury,10 Greater Wellington.12

Note: Due to some data limitations the 2007 and 2008 values for Christchurch may not reflect the maximum concentration experienced at this site.

Year Auckland (Penrose)
(µg/m3)
Auckland (Khyber Pass Road) (µg/m3) Auckland (Queen Street) (µg/m3) Wellington (Central) (µg/m3) Christchurch(St Albans)
(µg/m3)
1988         76
1989         85
1990 56       180
1991 37       82
1992 53       82
1993 49       62
1994 44       42
1995 51       49
1996 67       42
1997 68       49
1998 51 117     35
1999 58 119     41
2000 57 122     38
2001 54 135     51
2002 64 119     34
2003 55 107     50
2004 52 113 101   54
2005 53 121 99 70 37
2006 64 74 96 61 51
2007 56 69 91 70 42
2008 58 66 88 61 28

Figure 6: Annual nitrogen dioxide levels, 1989–2008

Figure 6: Annual nitrogen dioxide levels, 1989–2008

Source: Auckland Regional Council,9 Environment Canterbury,10 Greater Wellington.12

Note: Annual averages are not presented for some sites in some years due to data limitations.

Year Auckland (Penrose)
(µg/m3)
Auckland (Khyber Pass Road) (µg/m3) Auckland (Queen Street) (µg/m3) Wellington (Central) (µg/m3) Christchurch(St Albans)
(µg/m3)
1989         24
1990 17       29
1991 13       25
1992 25       -
1993 18       -
1994 18       -
1995 22       18
1996 20       15
1997 24       15
1998 22 62     14
1999 25 55     14
2000 23 57     13
2001 23 58     17
2002 27 59     -
2003 24 51     16
2004 24 58 56   16
2005 24 50 58 36 15
2006 25 37 50 33 16
2007 24 36 46 32  -
2008 24 33 49 37  -

Trend

Recent trend

Nitrogen dioxide was reported on in Environment New Zealand 2007. Since then, there have been fluctuations in the 1-hour and 24-hour maximums, and the annual averages at most of the five sites (see the new data presented in figures 4–6).

In 2007, 11 exceedances and two breaches of the 1-hour national standard for nitrogen dioxide occurred. These all occurred at the Queen Street site in Auckland, mostly during autumn and winter. These exceedances were probably due to road works occurring in Queen Street at the time. In 2006, the only exceedance of the 1-hour national standard for nitrogen dioxide also occurred at the Queen Street site in Auckland. All other sites monitoring nitrogen dioxide in New Zealand met the 1-hour national standard in recent years.

The 24-hour national guideline for nitrogen dioxide was met by all sites monitored in New Zealand in recent years. However, the Auckland (Queen Street) site has not meet the 24-hour WHO guideline in recent years.

Long-term trend

There is no clear trend in ambient levels of nitrogen dioxide at the long-term monitoring sites at Auckland (Penrose and Khyber Pass Road) and Christchurch. Maximum levels have fluctuated since 1990 and annual averages for all three sites show no discernible trend.