Table 1.
Averaged weekend-weekday ozone (O3) difference (expressed in %), annual trends for ozone weekend effect (OWE, expressed in % per year), and percentage of urban stations per trend category (decrease and increase) and per range of weekend-weekday ozone difference over the time period 2005–2014 (as well as 2005–2018 for Germany and United States) ± standard deviation (N: number of stations). We divided the urban stations into three types: no or low O3 weekend effect (weekend-weekday difference < 5%), moderate O3 weekend effect (5% < weekend-weekday difference < 15%) and high O3 weekend effect (weekend-weekday difference > 15%).
| Countries | Time period | N | Weekend-weekday O3 difference |
Saturday-weekday O3 difference |
Sunday-weekday O3 difference |
OWE trends |
Increasing trend |
Decreasing trend |
Percentage of monitoring stations per range of weekend-weekday O3 difference |
Trends per range (% year-1) |
||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| % | % | % | % year−1 | % of stations | x < 5% | 5 < x < 15% | x > 15% | x < 5% | 5 < x < 15% | x > 15% | ||||
| Canada | 2005–2014 | 35 | 11.7 ± 3.1 | 11.4 ± 3.4 | 12.0 ± 4.6 | - 0.09 ± 0.56 | 48.6 | 51.4 | 27 ± 14 | 41 ± 11 | 32 ± 14 | - 0.95 | +2.86 | - 1.43 |
| France | 2005–2014 | 136 | 10.9 ± 5.4 | 9.3 ± 5.1 | 12.6 ± 6.1 | +0.90 ± 0.75 | 87.5 | 12.5 | 24 ± 26 | 74 ± 26 | 2 ± 5 | - 2.81 | +4.60 | 0 |
| Germany | 2005–2014 | 79 | 14.8 ± 3.5 | 10.6 ± 4.2 | 19.1 ± 3.4 | - 0.45 ± 0.31 | 13.9 | 86.1 | 3 ± 2 | 52 ± 21 | 45 ± 24 | +0.38 | +3.80 | - 3.80 |
| Italy | 2005–2014 | 50 | 9.0 ± 4.1 | 8.6 ± 4.1 | 9.5 ± 5.1 | - 0.10 ± 0.94 | 46.9 | 53.1 | 39 ± 14 | 36 ± 14 | 25 ± 12 | - 0.85 | +1.29 | - 0.41 |
| Japan | 2005–2014 | 55 | 14.3 ± 5.6 | 12.7 ± 6.8 | 15.9 ± 6.5 | - 0.17 ± 0.67 | 44.4 | 55.6 | 20 ± 20 | 37 ± 13 | 44 ± 25 | - 0.15 | - 0.64 | - 0.16 |
| South Korea | 2005–2014 | 200 | 9.9 ± 4.8 | 9.5 ± 6.6 | 10.3 ± 6.0 | +0.46 ± 1.10 | 64.0 | 36.0 | 40 ± 18 | 28 ± 7 | 32 ± 13 | - 1.79 | +0.70 | +0.43 |
| Spain | 2005–2014 | 77 | 12.3 ± 7.0 | 11.3 ± 7.1 | 13.2 ± 7.2 | 0.01 ± 1.94 | 55.8 | 44.2 | 31 ± 15 | 35 ± 10 | 34 ± 18 | - 0.15 | +0.98 | +1.08 |
| United Kingdom | 2005–2014 | 29 | 16.6 ± 12.2 | 16.6 ± 14.1 | 17.2 ± 14.5 | +2.10 ± 1.62 | 93.1 | 6.9 | 27 ± 19 | 27 ± 18 | 47 ± 33 | - 3.01 | - 1.59 | +6.46 |
| United States | 2005–2014 | 147 | 8.1 ± 6.4 | 6.7 ± 6.0 | 9.5 ± 7.8 | - 0.50 ± 0.55 | 15.6 | 84.4 | 34 ± 13 | 55 ± 10 | 11 ± 5 | +3.43 | - 2.04 | - 1.15 |
| All stations | 2005–2014 | 808 | 11.8 ± 5.9 | 10.5 ± 6.5 | 13.1 ± 6.9 | + 0.24 ± 0.80 | 52.4 | 47.6 | 26 ± 20 | 43 ± 18 | 31 ± 22 | - 0.65 | + 1.10 | + 0.11 |
| Germany | 2005–2018 | 79 | 13.4 ± 4.2 | 9.2 ± 4.6 | 17.7 ± 4.3 | - 0.65 ± 0.30 | 2.5 | 97.5 | 8 ± 11 | 56 ± 19 | 37 ± 26 | +0.89 | +2.25 | - 4.43 |
| United States | 2005–2018 | 147 | 6.9 ± 5.8 | 5.6 ± 4.2 | 8.1 ± 7.0 | - 0.55 ± 0.53 | 11.6 | 89.4 | 38 ± 11 | 53 ± 11 | 9 ± 4 | +2.23 | - 1.74 | - 1.75 |