Outdoor air quality affects indoor air quality

The Westminster Commission for Road Air Quality’s Air Monitoring Working Party highlighted the urgent need to protect students from dirty and toxic outside air penetrating classrooms in addition to ensuring that there are sufficient air changes to reduce the risk of Sars-Cov-2.

Douglas Booker, co-founder and CEO at NAQTS, spoke to the Air Monitoring Working Party, chaired by Ralph Wilce, on 24 September 2021 about measuring air quality in indoor environments.

Douglas is a part-time PhD researcher who uses a combination of natural and social science methods to measure air quality in and around schools. He runs NAQTS, a Lancaster Environment Centre co-located business that develops tools and technologies to provide independent, reliable, and holistic air quality information.

We spend 90% of our time indoors, where we are exposed to a significant proportion of air pollution, Douglas explained. He provided the audience with insights from a nationwide project measuring indoor air quality in schools, both pre-and post-Covid.

He explained the need to understand how outdoor air quality affects indoor air quality. ‘Just opening windows is not the answer because dirty air from outside will enter the classroom.’

His project on schools highlighted the urgent need to protect students from dirty and toxic outside air penetrating classrooms, in addition to ensuring that there are sufficient air changes to reduce the risk of Sars-Cov-2. Some harmful airborne pollutants, such as combustion-generated ultra-fine particles, are not yet being measured to quantify the risk to public health, especially those close to the sources. Developing lower-cost sensors for measuring ultrafine particles is in full swing, and WCRAQ will be providing regular updates.

As an example of the need to focus on the source, the ‘stop idling campaign’ raises the issue of emissions generated by excessive idling of petrol and diesel engines. However, if we ensured that the diesel vehicles had active diesel particulate filters, we could tackle the source of the problem.

Ralph Wilce stated the difference between a modern Euro 6 van with a working DPF, emitting virtually zero particles at idle, compared to 20 million particles per cubic centimeter once the driver had removed the DPF. However, the van would typically pass the MOT diesel test without the DPF.

‘So perhaps we should focus on the fact that if diesel vehicles were idling with working DPFs, emissions would be extremely low, with particle emissions below ambient levels. The filters would, in a sense, be filtering the ambient air of particles,’ said Ralph.

‘The same applies to other modes of transport that use diesel engines, such as rail and waterways. Apply a working filter, and PM emissions reduce by 95% or more. Also, for non-road mobile machinery, where the latest regulations require the fitting of DPFs, such legislation will also need to be enforced through proper in-use testing.’

Originally published in the FVI magazine