Planning after lockdown: Why we need to talk about indoor air quality

Before COVID-19

For many of us, our ‘pre-COVID’ lives involved leaving our homes and commuting to work each day to spend time in another indoor space, such as an office, workshop, factory, shop, café or restaurant. During the evenings and at weekends, we might have spent time in a variety of other indoor spaces, such a gym, restaurant, pub, theatre or a cinema.

During lockdown

Except for key workers, the Government required us to stay at home during the height of the lockdown with only one hour outside allowed for exercise. Even as the lock down eases, the Government is still advocating that people work at home wherever this is an option. For many of us, this means we will have spent more time at home than ever before. The sources of outdoor air pollution are relatively well known, and most people are now aware of the health-impacts associated with ambient (or outdoor) air pollutants. But fewer people will be aware that even when we are inside, we can be affected by air pollutants.

Indoor air pollutants explained

This shouldn’t really be a surprise if we think about it: we don’t generate air inside our buildings; it is brought in from the outside by one means or another and that may be by natural ventilation (e.g. windows, air-bricks) or mechanical ventilation. If the whole area has high outdoor air pollution levels, this will permeate the interiors of naturally ventilated buildings. For mechanically ventilated buildings, steps can be taken to try to place the air intakes away from places where outdoor pollution is highest, or filters can be used. Our air quality assessments help with the design of these mitigation measures by forecasting the pollution concentration levels at the different building façades to guide developers in understanding the best location for air intakes.

On top of whatever quality air is brought in from outside, is the air pollution created within our indoor spaces. These pollution sources include heating and cooking appliances but can also include paints, coatings, cleaning products, carpets and upholstery. Often not widely known, the air pollutants generated by indoor sources can be just as harmful as those created outside by traffic. Their effects can be magnified in buildings with poor ventilation because these pollutants are trapped within a confined indoor space. For example, when a scented candle is lit, indoor levels of highly harmful fine particulates can be seen to rise to thousands of microgrammes per cubic metre; compared to levels outdoors that are mostly in single figures.

The Department for Environment Food and Rural Affairs’ Clean Air Strategy 2019 dedicated an entire chapter to actions to reduce emissions at home, stating that “Awareness of the exposure that takes place in the home is currently very low. The government’s objective is to raise awareness of the potential impacts of air pollution at home and ensure that consumers are armed with reliable information enabling them to make informed choices to protect themselves, their families and their neighbours.” At present though, the World Health Organisation and Public Health England both set guidelines for pollutants that apply in any indoor space (i.e. in workplaces and in homes) but they do not provide assessment levels for all the substances that can be found in an indoor environment. The Control of Substances Hazardous to Health Occupational/Workplace Exposure Limits provide assessment levels for a wider range of pollutants but these are generally set at higher levels as they apply to healthy individuals working in industrial settings. In other words, these levels might not be appropriate for everyone.