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Covid lockdown associated with 41% drop in hospital admissions for asthma

New research from OxAria has found that the improvement in air quality during the Covi-19 lockdown led to a 41% fall in the number of adult admissions for asthma, compared to the previous five year average.

OxAria is a collaboration between the University of Birmingham and University of Oxford which has been examining the air and noise quality impacts of COVID-19 across Oxford City. 

The study analysed the monthly hospital admissions for adults with a primary diagnosis of acute asthma, from the start of January 2015 to the end of December 2020. Hourly concentrations of NO2, PM2.5 and PM10 for the same period were obtained from the ARUN station at St Ebbe’s school in the city.

Comparing the average air pollution levels between 2015 and 2019 with those in the lockdown year of 2020, the following changes could be seen:

NO2: fell from 14.6 µg m³ to 10.7 µg m³  (a reduction of 26.7%)
PM2.5: fell from 10.1 µg m³  to 6.7 µg m³ (a reduction of 33.5%)
PM10: fell from 13.2 µg m³  to 10.8 µg m³ (a reduction of 18.6%)

The chart shown here compares the average asthma admissions for 2015-19 in blue and the 2020 admissions in black. It is important to note, when looking at the 2020 figures, that the two lockdown periods (when there was considerably less traffic on the roads) were 23rd March to 15th June and 5th November to 2nd December.

The researchers considered that there was  fall in all non-Covid admissions during this time – in an effort to ‘Protect the NHS’ – but balanced this with the fact that ‘acute asthma is a severe condition which requires urgent hospital management and therefore it is likely that most patients in this study accessed emergency care following an acute attack.’

Dr Suzanne Bartington, Clinical Associate Professor of Environmental Health at the University of Birmingham and lead author of the study said: ‘The impact of lockdowns on reductions in traffic and industry led to a unique situation where air quality significantly improved for a temporary period during the COVID-19 pandemic. This study shows that for Oxford, levels of major air pollutants including nitrogen dioxide and particulate matter fell sharply on a background of ongoing improvements in recent years.

‘The results of air pollution levels falling may have had an impact on the number of severe asthma cases that need acute hospital care, with 41% fewer hospital stays compared to the previous five-year average. Furthermore, we also identified a 4% increase in risk of asthma hospital admissions for every 1 μg m-3 increase in mean monthly NO2, and an approximately 3% increase in risk for every 1 μg m-3 increase in mean monthly PM2.5 levels.

‘This is an important study to help us better understand how demand for NHS inpatient care may change when air quality is improved. Whereas previous studies on lockdown air pollution have focused on major cities in the UK such as London or Birmingham, Oxford is more typical of a smaller city or large town where many residents live.’


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Peter Murtagh
Peter Murtagh
3 months ago

This is welcome news. However, since the end of the pandemic the volume of traffic has again increased. Worryingly, according to a report , May 2023 , by the reputable agency Ricardo on the Scottish Air Quality website (official ScotGov site. ) ,”13 local authorities have declared AQMAs for Particulate Matter (PM10)1 with several considering the potential for revocation where concentrations have been consistently below the annual mean objective” ie to withdraw from their mandatory duties, and costs, as an unnecessary expense and burden, citing the decrease in recorded levels of pollution during the pandemic. The Ricardo report advises caution on the use of these figures as a basis for such a policy. It is all the more important to maintain the monitoring , and to analyse the changes, to obtain accurate evidence. Its anecdotal, perhaps, but living near a busy primary school entrance and I see and experience the impact of increased traffic flow. Covid had a huge impact on air quality . The return to more normal schooling didn’t bring immediate drastic change, as the spike in fuel prices meant more guardians walking their charges to and from school. For a time. But now its back to normal, with cars idling outside for 45 mins at a time. The average is about 25 mins. There are plenty of signs up, and I hand out plenty of leaflets about the health dangers. Especially when there are babies in the cars .Many are responsive ; but a hardened minority less so . I suppose we can’t expect individual guardians to act responsibly when those in authority seek to avoid their’s ?

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