‘The virus is still out there’
Professor Tim Sharpe, head of the architecture department at the University of Strathclyde and member of SAGE, answers questions about safe ways to meet outdoors
Q If the vaccine programme is going so well, why can’t we open up more quickly?
A The vaccine programme is going well, but it’s still going. We’re on a journey, and we’re not at the end of that journey yet. So, although a lot of people have been vaccinated, a lot haven’t and are still at risk. And those risks are still the same. Until a much larger number of people are vaccinated, there will still be those significant risks of catching Covid. The virus is still out there. This is certainly going to be the case for a few months yet. Certain groups are a long way from being vaccinated – and you’ve seen the news recently that supply chains for the vaccine may affect the rate at which the rollout can happen. Part of this is just being slightly cautious about it. So we’re taking one step at a time. What you don’t want to do is run before you can walk and then have to roll back. That would be a worstcase scenario. Taking a precautionary approach is the best way to do this.
Q How does the virus spread indoors?
A Most of the transmission has happened indoors for various reasons. Buildings are where people come together for work and to socialise. They are where you have people in close proximity, talking and interacting. The second issue is that the virus can accumulate over time, so you’re breathing its particles. If you’re further away, it’s less of a risk, but if you remain in that space for a long time and it’s poorly ventilated, they build up.
Q So we’re much safer outdoors?
A Yes. People are further apart, you have fresh air, the virus is diluted, it dries out and sunlight may help. It’s a natural cleansing agent, so UV light may play a part as well. Fresh air and sunlight are healthy for many reasons.
Q Is it important to define the differences between airborne and aerosol droplets?
A There’s no hard dividing line, but larger droplets will drop to the floor pretty quickly, and smaller droplets will stay in the air, move about and accumulate over time.
Q Is aerosol still a concern outside? Is that why we need to observe social distancing rules?
A It’s less of a concern outside because it’s not contained. Indoors, it’s like someone smoking: if you were sitting next to them you could see the smoke and everyone could smell it. Where you are outdoors makes a difference, too. If you’re standing by the seaside and it’s a windy day it’s perfect, but if you’re in a market or a more enclosed space there’s less air movement and the risk is correspondingly higher. These are the sort of judgments we need to think about.
Q Why can’t we have football and horse racing crowds back yet?
A The more people you have, the more times you’re rolling the dice, the more risk there is. And when you have crowds, people get pushed in together, they’re very close. Crowds sing, chant and shout – all of those are aerosol generating procedures. So that is a risk factor. Then there’s getting to and from the event, plus going to bathrooms, eating and all those other dimensions that are part of the problem. And with a larger crowd, the chance that someone there has Covid is greater than if it’s a small gathering of people.
Q What advice would you give to people who are meeting up outside?
A Don’t let your guard down. People may start with the best intentions – we all do it, you meet someone in a park and you’re standing and chatting and you gravitate closer, maybe because you can’t hear. I think that’s where it’s dangerous – you don’t maintain a strict adherence to the rules over time. The longer you spend with somebody the more you tend to relax. So just be cautious.