London network in health advice over ozone spike

Health alerts have been issued to schools in London due to the ongoing presence of moderate levels of ozone across the capital.

In some parts of the country high levels of ozone (<180 µg/m3) have been monitored in short spells prompting automatic alerts via the government’s  UK AIR monitoring service over the last week (see story).

King’s College London is the Duty Forecaster for air pollution on behalf of the Mayor of London

In the capital, the London Air forecasting and monitoring service, which is run by King’s College London, has issued ‘Moderate’ pollution forecasts for both today and tomorrow, based on the weather conditions and presence of chemicals likely to produce ozone.

In its bulletin for Tuesday London Air noted that the presence of oxides of nitrogen, Volatile Organic Compounds (VOCs) and carbon monoxide in the air, alongside long hours of unbroken sunshine “is likely to contribute to ground level ozone formation resulting in ‘moderate’ pollution.”

KCL carries out the role of ‘duty forecaster’ on behalf of the Mayor of London, targeting messaging when pollution levels are thought likely to be harmful to vulnerable members of the population include schoolchildren and the elderly (see story).


Speaking at the annual London Air Quality Network annual conference this morning (3 July), Timothy Baker, principal air quality analyst at KCL, confirmed that alerts have been issued this week via the ‘stakeholder group’ established by City Hall.

He said: “GLA [the Greater London Authority] has asked us to do forecasting, so alerts have been going out to all schools and to contacts who should be disseminating it onto hospitals, care homes and things like that. That is about 4,000 recipients of those forecasts. So each day during this episode there has been an alert from the GLA.”

Commenting on the conditions that have led to ozone levels spiking over the past week, he said: “As we have been reducing the other pollutants which actually scavenge ozone and reduce ozone within London the actual levels of ozone are increasing. What we are seeing now is; where we used to get this sort of episode from July to August, what we have been seeing is that they tend to start earlier.

“They are not unusual, they have been happening for decades, but it is just that they are becoming more visible because they are pushing the limits on the daily air quality index.“


So far during the current pollution episode, air quality alerts have been triggered automatically via the UK Air service due to the monitoring of ozone concentrated above the 180 µg/m3 threshold. Under EU law, member states are required to inform the public if this threshold is breached over a 1-hour period at any of its monitoring sites.

However, ozone levels are only considered to be ‘high’ on the national Daily Air Quality Index if monitored at an average level of between 161-187 µg/m3 over an eight hour period, at which point more severe public health warnings are to be expected. This has yet to happen at any of the UK’s monitoring sites over the last week.

Commenting on the health advice to the public issued during similar pollution episodes, Dr Karen Exley, of Public Health England, said: “While most people will not be affected by short term peaks in ambient air pollution, some individuals, such as those with existing heart or lung conditions, may experience increased symptoms.

“On occasions where levels are high, adults and children with lung problems, and adults with heart problems, should reduce strenuous physical exertion, particularly outdoors, and particularly if they experience symptoms. People with asthma may find they need to use their reliever inhaler more often. Older people should also reduce physical exertion. Anyone experiencing discomfort such as sore eyes, cough or sore throat should consider reducing activity, particularly outdoors.”

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