Secondary Impacts of a Heatwave

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The summer of 2022 was unlike any other, as temperatures reached record-breaking heights of 40˚C in the UK for the first time, with Lincolnshire recording a high of 40.3˚C, 1.6˚C higher than the previous record set in 2019. These astonishing temperatures prompted the Met Office to issue a Red Extreme Heat Weather Warning, the UK Health Security Agency to announce a Level 4 Heat Health Alert, and the UK government to declare a national emergency, before several fire services declared major incidents as they battled wildfires that had broken out on grass and heathland. 

Following discussions with partners and internally, one of the lessons drawn out was that many are unaware of the indirect or secondary impacts that heatwaves can have. By identifying these, and the communities who may be most affected, we can take action to try and mitigate the impacts, educate people, and potentially reduce the risk of the secondary emergency happening.  

You can access a variety of heatwave resources on the EP heatwave preparedness webpage here. There is also advice on how to stay safe in hot weather in British Sign Language (BSL) available from Action Deafness here.  

What are the secondary impacts of heatwaves? 

1. Wildfires 

Although more commonly associated with Australia, the USA and countries in Southern Europe, wildfires have been included in the UK’s National Risk Register since 2012. In recent years, the devastating impacts have been all too clear, with a major fire in Wennington, London, last summer destroying 19 homes. Figures show that between June and August 2022, England faced nearly four times more wildfires than the same period in 2021, and two and a half times more than in 2020.  

Heatwaves with lengthy periods of hot, dry weather can mean that grassland, heathland, and vegetation become extremely dry, and therefore the perfect fuel for a fire. Whilst the initial spark for a wildfire can be caused by a lightning strike, it is far more common for human intervention to play a role. According to Devon and Somerset Fire and Rescue Service, only 10-15% of wildfires are caused by nature, with the vast majority caused by human activity, including making and not properly distinguishing bonfires and campfires, and discarded disposable BBQs, cigarette butts and glass bottles. Natural England has said that some of the biggest causes of wildfires in England come from people and their lack of understanding of how behaviour can affect natural spaces.  

Resources:  

• Organisations can find resources to share with, and educate, their communities about how to prevent wildfires, from the British Red Cross, here, and the National Fire Chiefs Council, here. 

2. Flash Flooding  

Whilst the UK may not be known for extremely high temperatures and heatwaves, it is certainly known for its changeable weather. However, when extended periods of hot, dry weather end, thunderstorms can soon arrive, and many can be unprepared for the impacts they can have.  

After intense heat and no rain, the ground can become so parched that it absorbs water much more slowly than both wet grass and ‘normal’ moist grass. Last year, a video by the University of Reading demonstrating this was featured in newspapers, on TV, and shared widely on social media. 

Being unable to absorb rainfall quick enough, particularly during heavy rain and thunderstorms, is what leads to flash flooding. This type of flooding is particularly prone in urban areas where there is far less green space to absorb rainfall and more impermeable surfaces (concrete) that create surface water run-off. If the small amount of green space is also parched, rain is left with little option but to pool or run down our streets. Following extreme heat in August 2022, torrential downpours led to flash flooding, with train stations affected in London and roads flooded in Cornwall and Lincolnshire. 

It is important to note that even if communities know flooding is likely, not everyone will have the resources to protect themselves or their home, particularly low-income households. Flash flooding can also occur with short notice, and so those who are elderly, disabled or have health conditions, may struggle to react as quickly. Therefore, they may require support to prepare and respond. 

Resources:  

• You can find out if your community is at-risk of flooding, whether from rivers, reservoirs, or surface run-off, by entering your postcode here. You can sign up for flood alerts here.  

• The British Red Cross has resources to help people prepare for floods with advice for before, during and after a flood, here.  

• The Greater London Authority has a leaflet about flash flooding in London, here.   

3. Air Pollution 

Sun, high pressure, and hot temperatures associated with heatwaves, can all impact air pollution levels. Chemical reactions caused by this weather triggers the traffic pollutants nitrous oxides to become ozone, a gas that causes inflammation in the eyes, nose, and throat, particularly affecting asthma sufferers, those who are elderly or young and people with lung conditions, such as COPD. 

Research by the National Centre for Atmospheric Science found that the record-breaking temperatures in July 2022 led to “dangerously high” levels of ground-based ozone, with some monitoring stations recording levels double the World Health Organisation guideline limit. Dr Grant Forster, from Weybourne Atmospheric Observatory, said:, “dDue to the effects of climate change, we can expect to see heatwaves more often, leading to a higher frequency of dangerous ozone pollution events across the UK.” 

Studies have shown that particular groups of people are more likely to live in higher pollution areas. Friends of the Earth analysed government data, finding that 50% of the communities with high air pollution are within the 30% most deprived, and that approximately 44-47% of people in these areas are from minority ethnic backgrounds. Local organisations may be aware of those in their communities who either have health conditions that make them more vulnerable or live in areas of high pollution that could be more at-risk in hot weather. 

Asthma and Lung UK’s top tips for days with high air pollution include: 

• Limit outdoor activities or go out earlier in the day to avoid breathing in too much pollution.  

• Stay on quieter streets if possible, avoiding high traffic areas where pollution is high. 

• Be prepared by checking pollution levels in your area. The Department for the Environment, Food and Rural Affairs (DEFRA) publishes a UK-wide forecast here.