Pollution episodes

Over the summer of 2024, there were no major ozone pollution episodes in Oxfordshire. However, there were 15 days when pollution levels were moderate.
 

The first moderate ozone day was April 6th, followed by six more periods of increased ozone levels:

• May: 9th–12th & 19th–20th
• June: 2nd & 25th–26th
• July/August: 19th July & 29th July–1st August

These pollution peaks happened during warm weather when winds from southeastern Europe brought air pollutants that contribute to ozone formation.
 
It's important to know that ozone pollution is not just a local issue. Even though ozone is only measure at Oxford St Ebbes, it represents the regional ozone concentrations because ozone spreads across large areas, affecting thousands of people. 
 
While moderate ozone levels are not considered dangerous for most people, they can still cause problems for those with asthma, young children, and the elderly.  

During early June and the start of September 2023, England experienced widespread moderate to high ground-level ozone air pollution, due to hot, sunny weather with light easterly winds coming from continental Europe.

Ground-level ozone is a secondary pollutant, which means it is not directly emitted by traffic or other direct source. It is typically formed in Spring or Summer, when the days are warm, sunny and the air is stagnant, due to the influence of solar radiation on a cocktail of airborne pollutants, also called ozone precursors.
 
When these conditions are met, ozone is produced, and its levels tend to build up. Ozone is a regional pollutant, so a single ozone monitoring site may represent the regional ozone concentrations that hundreds of thousands of people are exposed to.

On the 5th November the UK celebrates Guy Fawkes Night, or “Bonfire Night”. The activities of lighting bonfires and setting off fireworks cause emissions of particulate matter (PM₁₀, PM_2.5).

In 2023 weather conditions in Oxfordshire were rainy on the weekend of the 4th/5th November. This may have reduced the amount of fireworks being let off, which in turn meant that there was not a noticeable increase in pollution normally associated with fireworks.

In November 2023 the daily air quality index (DAQI) across Oxfordshire remained within the “low” (1-3) band, which is associated with no adverse public health advice for even the most vulnerable in the population.

Particulate matter (PM) consists of solid particles and liquid droplets small enough to be suspended in the air.  Fine particles can be carried deep into the lungs where they can cause inflammation and a worsening of heart and lung diseases.