The environmental effects of lockdown
concentration during the sunny parts of the day and reaching much lower concentrations at night. Therefore, looking at 8 hour running mean data will give a much more accurate indication of ozone levels throughout the day.
Data recorded in Bournemouth of ozone concentrations show that the number of recorded times that ozone concentrations exceed the recommended levels for an 8 hour running mean, set by the WHO in the Air Quality Guidelines, of 100 µg/m³, over this period in 2019 was 103 occurrences compared to 244 in 2020. 12
However, as Figure 2 shows, levels of NO x gases in 2020 were significantly reduced compared to the previous year. For NO and NO 2 levels the highest levels occur earlier on in the year, around January and
Figure 2. The 8 hour running means of O 3 concentrations from January to July, with 2019 and 2020 data. Also, 2019 and 2020 daily mean data for NO x concentrations for the same time period. Data taken from the DEFRA website.
12 World Health Organization. ‘ WHO Air quality guidelines for particulate matter, ozone, nitrogen dioxide and sulfur dioxide’ . (2005). https://apps.who.int/iris/bitstream/handle/10665/69477/WHO_SDE_PHE_OEH_06.02_eng. pdf;jsessionid=228B58FB911064BA54B1DF1798DC7DEB?sequence=1.
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