Low temperatures, low wind and low rain increases PM2.5 fourfold

Fig. 1: PM2.5 4-hour average in October- December period. The black horizontal line represents an average of AirNodes for December. The black dashed line represents temperature observed in the AirNode.the

AirScapes PM2.5 data shows a great increase (over 200%) in PM concentration in December compared to earlier months (Fig.1). The increase in PM concentration is more visible in the 1st half of December (Fig. 2), especially between 8th and 17th of December when average temperature oscillated around 0oC. 

Fig. 2: PM2.5 hourly average in December. The black horizontal line represents an average of AirNodes for December. The black dashed line represents temperature observed in the AirNode

The PM2.5 pollution in that period was on average four times higher than the average pollution of the last two months (October and November). 

The increase can be probably attributed to an increase in wood burners usage or other ways of increasing temperature in residential areas. The high concentration of PM can be further explained with low precipitation and low wind speed during that period, which would enhance the polluting effect of  local sources. 

Contrary to the 1st  half of December, the 2nd  half saw a decrease in PM concentration. This might be an outcome of a combination of  both higher temperatures (lesser usage of wood burners) and increased rainfall and wind  speed.   

Read the full analysis here

AirScape would like to wish everyone Happy Holidays as 2022 draws to a close. 2022 has been an incredible journey for our company, with data coming in from installations at the Port of Dublin, Port of Aarhus, Staffordshire, and the crown jewel, AirScape’s installation of the world’s largest dense network of air pollution monitoring sensors in the Borough of Camden in London. We would like to present some of the highlights of this year.

First field trial of the new AirNode

During the first quarter of 2022 we were commissioning the system and the first data started to come in. At the end of February we saw a massive shift in carbon dioxide levels across the borough. Very quickly we could eliminate many potential causes such as data quality and local emission. Finally we used a global model of atmospheric meteorology from the National Oceanographic and Atmospheric Administration (NOAA) in the USA to determine the source, a subglacial volcano on Iceland called Katla that turns out to be the largest natural source of CO2 in the northern hemisphere. This plume of CO2 took about half a week to cross the North Atlantic before descending on Camden.

The non-strike average for PM2.5 is around 6 ug/m3 while the average during the strike was 25 ug/m3, an increase of 19 ug/m3 or 316 %. Maximum values ranged from 35 to 50 ug/m3, a max 833 % increase.

Throughout the year the monitoring network has seen many details of day to day life. Rail strikes in early March meant increased traffic as Londoners used vehicles to go about their business. The network recorded 3 % increase in CO2, 66 % in NO2 and 316 % in PM. During the August rail strike we saw the opposite — many people simply stayed home, and air pollution dropped.

There was a fire on a roof at Chalk Hill Farm in June. We were recording an interview with the BBC at the Camden Locks and the cameraman saw a plume of thick black smoke through the camera. Our sensors were able to record the event, showing when and where it occurred and how quickly it could be extinguished. In addition to air pollution, we hope that monitors such as ours will also contribute to increased public safety in episodes like this.

The largest story of the year in our opinion, is that Camden continues to struggle with air pollution. We see pollution events every day, both large and small, lasting from minutes to days, that are cause for concern for anyone in Camden. We are very glad for the continued collaboration with Camden Clean Air Initiative because we can work together to increase awareness. We are also extremely grateful for the support we have received from the Camden City Council which ranges from logistical support with mounting the sensors, to their pledge to improve air quality for residents of Camden. This includes the pledge to bring Camden into compliance with the new WHO Air Quality Exposure Guidelines.

Thanks to everyone for your support and we are looking forward to new adventures in 2023.

The UK Chief Medical Officer Annual Report is a clear and convincing call to action.

This year’s report lays out the scale of the challenge of reducing air pollution, the substantial progress that has been made and highlights achievable solutions.

The report identifies many win-win (or win-win-win!) scenarios. For example, increasing active travel like walking and biking will reduce toxic air pollution, decrease greenhouse gas emissions and directly improve health through physical activity.

‘The path to better outdoor air quality is clear, and we need to go down it.’

The report points out that there is still a long way to go. With current policies, by 2030, all of southern and eastern Britain is projected to exceed the WHO annual exposure threshold for PM.

Regarding Urban Planning the report states

‘Urban planning should support reducing air pollution concentrations locally – such as reducing air pollution near schools and healthcare settings. Shifting to active travel where possible has direct health wins as well as reducing air pollution from vehicles planning should support this.’

Street-level air quality data in real time will be essential to measure the impact of these solutions.

Click here to read the report in full.

The European Union is preparing to update its Air Quality Directive, slashing the exposure thresholds for NO2 and PM, and bringing them into line with the recent recommendations of the World Health Organization.

This expert opinion, from the most respected voices in the atmospheric chemistry community, recommends that dense networks of low-cost air pollution sensors be included as an integral part of monitoring programs, as the only way to guarantee compliance and protect people.

“This article provides an informed opinion on selected features of the air quality directive that we believe would benefit from a reassessment. The selected features include discussion about

(1) air quality sensors as a part of a hierarchical observation network,

(2) the number of minimum sampling points and their siting criteria, and

(3) new target air pollution parameters for future consideration.”

Opinion: Insights into updating Ambient Air Quality
Directive 2008/50/EC

They argue that the best way to get the job done, the only way, the cheapest way, is to install high density sensor networks across high population density areas in Europe.

AirScape provides street-level air quality data in real time. By supplementing the existing monitoring stations, we help cities come into compliance with the coming revisions to the EU exposure limits.

The European Union intends to revise its ambient air quality directive (2008/50/EC) so they are more closely aligned with the World Health Organization (WHO) guidelines published in 2020.

The revision of the Ambient Air Quality Directives will merge the Directives into one, and seek to:

  • align EU air quality standards more closely with WHO recommendations
  • further improve the legislative framework (e.g. in relation to penalties, and public information)
  • better support local authorities in achieving cleaner air through strengthening air quality monitoring, modelling and plans.

We think this revision is overdue.

It’s a step in the right direction, but there is evidence that it still is not going far enough.

This revision will result in a decrease in mortality and an improvement in quality of life. It is good news for people and it is good news for the economy. Enforcement is crucial.

It is also time to revise the measurement station based observation network. It’s expensive and sparse. Technology has advanced to the point where dense networks of low cost sensors can be used, especially in areas of high population density. In combination with fixed measurement stations, they greatly increase the temporal and spatial resolution of monitoring.

This is critically important as local emissions can only be seen effectively with a dense network. In many cases, these local emissions are the main factor when WHO guidelines are exceeded.

Critically, local emissions are under local control. Dense networks give local communities control of their own fate and empower local decision making.

This paper by our talented team in Copenhagen was published in the prestigious international peer-reviewed journal Atmospheric Chemistry and Physics. They used data from the Staffordshire network to answer the question, ‘Are dense networks of low-cost nodes better at monitoring air pollution?’

They found that the dense network sees a lot of pollution that is not seen by the regional monitoring stations, and that additional local pollution is what pushes concentrations over the WHO exposure threshold. The local component of pollution is large and often invisible to the regional stations.

‘We determine that at least 54.3 ± 4.3 % of NO 2 is from local sources, whereas in contrast, only 37.9 ± 3.5 % of PM 2.5 is local.’

Air pollution exhibits hyper-local variation, especially near emissions sources. In addition to people’s time-activity patterns, this variation is the most critical element determining exposure.

Compared to conventional air pollution monitoring stations, nodes containing low-cost air pollution sensors can be deployed with very high density.

In this study, a network of 18 AirNodes using low-cost air pollution sensors was deployed in Newcastle-under-Lyme, Staffordshire, UK, in June 2020.

‘The network average NO2 concentration was 12.5 µg m−3 higher than values reported by a nearby regional air quality monitoring station. This demonstrates the critical importance of monitoring close to sources before pollution is diluted.’

We found that data from our low-cost air pollution sensor network revealed insights into patterns of air pollution, and helped determine whether sources were local or non-local.

Read the full paper here

Wherever you stand on the pros and cons of Electric Vehicles (EVs), increasing the use of EVs will undoubtedly improve air quality.

At AirScape, we measure hyper-local air pollution in real time.  At street level, electric vehicles provide clear benefits for local air quality, with zero exhaust emissions.

Of course, even electric vehicles generate particulate matter through road, tyre, and brake wear. And they carry a hefty carbon footprint in their manufacture and in the production of batteries.  However, according to a 2021 study by the International Council on Transportation, emissions over the lifetime of electric vehicles in Europe are 66% to 69% lower than those from petrol cars.

Switching to electric vehicles could also help to minimise noise pollution, especially in cities where speeds are typically low and traffic is frequently at a standstill.

Another study in the US found that the use of EVs leads to substantial air pollution health and other benefits.

“Incentivizing a rapid uptake of EVs will improve population health nearly immediately as most benefits of reduced mortality attributable to air pollution accrue in the short term.”

Ernani F.Choma, John S.Evans, James K.Hammitt, José A.Gómez-Ibáñez & John D.Spenglerb

We installed our award-winning AirNodes at five locations in Cork, Ireland, which show that there are measurable improvements in air quality where there are no diesel and petrol engines. The success of Cork’s award-winning pedestrianisation project is also being hailed as a major step in making the city a much safer and healthier environment. 

Now AirScape in Camden is giving us minute-by-minute air quality data at street level. The expanded ULEZ and other initiatives are helping to clean up London’s air. More good news is that, according to the ONS, over half of younger drivers are likely to switch to electric in the next decade.

We’ll soon be able to see the improvements in air quality on London’s streets, at airscape.ai, and also see where there’s still room for improvement.

AirScape’s Chief Science Officer, Professor Matthew Johnson says:

“We do see the benefit of banning traffic on air quality in the centre of Cork. We’re watching AirScape in Camden closely to see how the shift in the composition of the vehicle fleet takes effect in London.”

Last week, AirScape saw many NO2 and PM events in Camden. These screenshots from airscape.ai were all on Thursday and, in the afternoon, we measured NO2 spikes of more than 100 ug/m3.

Transient exposure to high NO2 and PM is an immediate health risk and puts an extra strain on already overburdened NHS emergency resources.

The statistics on the impacts of air pollution tend to be more about the long-term effects of chronic exposure. However, we know it can also trigger symptoms and bring on serious illness immediately.

According to research by King’s College London, emergency services attended more than 120 additional cardiac arrests, more than 230 additional strokes, and nearly 200 more people with asthma requiring hospital treatment on days of high pollution.

When this report was published, Simon Stevens, the chief executive of NHS England, said: “It’s clear that the climate emergency is in fact also a health emergency. Since these avoidable deaths are happening now, not in 2025 or 2050, together we need to act now.”

It’s important to be able to see where and when the spikes occur, simply so you can avoid them.

It could save your life – today.

Residents complain about noise and pollution from building sites. Construction companies complain about the expense of sitting idle at night and at weekends when regulations are in place. By finding better methods we will help to improve life for everyone in the neighbourhoods and allow construction companies to make better use of the site, identifying low-impact methods and processes that can be performed at any time.

At AirScape, we are proud and excited to be a part of this lighthouse project. Our sensor network provides real-time monitoring of air quality and noise, on and around the construction site.

By measuring and documenting everything, there’s transparency for the company and for residents. It’s a win-win!

Project – The Green Construction Site of the Future
Project start: January 2021
Expected completion: December 2023

2030 climate targets and a large focus on pollution from construction sites near cities make it necessary to look at a green transition in the construction industry. Until December 2023, Per Aarsleff and the project Green Building Site of the Future will examine the effect of various measures on one or more selected construction sites.

Full-scale demonstration
The project establishes a data-driven, full-scale demonstration of the green building site of the future. The initiatives involve converting construction machines to electricity and other alternative fuels such as HVO or GTL. Some special machines that cannot be converted will have a particulate filter and SCR catalyst fitted. In addition, CO2-reducing energy systems will be established. For example, solar cells and digital tools will contribute to on-site logistics optimization and smart behaviour.

Sensors measure the effect
Sensors on the site, and on the individual vehicles, will measure the effect of the actions, which will be implemented individually. With the help of sensor technology and location data, among other things, a heat map shows where, for example, a tractor has run, what it does and how much it costs in terms of emissions of particles and CO2. The goal is to create a so-called digital twin that documents current driving, and where it is possible to see how logistics can reduce driving and thus emissions and CO2.

Solar cells and heat pumps are integrated
A further initiative is a smart energy infrastructure with solar cells and heat pumps on the scavenger trucks, supplemented by energy storage for balancing the load. The Danish Technological Institute will uncover and analyse electricity consumption to identify possible energy savings and increased flexibility.

Evidence for green initiatives
The purpose is to provide the industry with evidence of which green initiatives provide the most climate and environmental impact for the money. The vision is that the project will contribute to the sustainable society of the future, where the availability of sustainable alternatives causes more builders to demand more sustainable building sites.


Per Aarsleff A/S
AirScape Denmark
Alumichem A/S
Purefi A/S
Cat’s field
DCE – National Center for the Environment and Energy, Aarhus University
Aarhus University – Engineering
Volvo Construction machines
Institute of Technology (project manager)

The project is supported by the Danish Environmental Protection Agency’s MUDP program and is a so-called lighthouse project and is carried out in close cooperation with the client, Ejendomsselskabet Olav de Linde A/S.

Read more about the Green Construction Site of the Future in their press release here.

Wildfires are dangerous, and an example of regional air pollution. Extreme heat and drought conditions have made it even worse in Europe and North America. You can see their extent on this map from NASA which shows the actively burning fires around the world.

Wildfire smoke can rise into the atmosphere in a plume and descend half a continent away, blanketing the area with choking toxic air pollution. People may not even be aware they are breathing in the fumes from a faraway forest fire, and that it’s affecting their health.

Through surveying the primary peer-reviewed research literature over the last few years, we can share with you our main findings:

  • Consistent evidence documents associations between wildfire smoke exposure and general respiratory health effects. Exacerbations of asthma, cardiovascular disease, chronic lung diseases such as emphysema, obstructive pulmonary disease and increased risk of respiratory infections are regularly reported.
  • During a wildfire in Spain, PM2.5 values were 75x higher than the WHO standard.
  • Other wildfire emissions like VOCs may cause skin and eye irritation, drowsiness, coughing and wheezing. Others like benzene may be carcinogenic.
  • A 5% increase in non-accidental mortality at a lag of 1 day was observed on days of high air pollution from bushfire smoke in Sydney.
  • Climate change is likely to increase the threat of wildfires.
  • In the US, daily pollution levels during or after wildfire in most studies exceeded U.S. EPA regulations.
  • Levels of PM10, the most frequently studied pollutant in the US and Australia, were 1.2 to 10 times higher due to wildfire smoke compared to non-fire periods and/or locations.
  • Children, the elderly, and those with underlying chronic diseases appear to be susceptible.
  • Ten years after the 1997 Indonesian fires, young males suffered decreases in lung function.
  • The economic valuation of the health impacts of wildfire emissions from across North America (from May-Sept between 2013 and 2015 and 2017-2018) was estimated per year at $410M–$1.8B for acute health impacts and $4.3B–$19B for chronic health impacts.
  • Wildfire particulate matter may be more toxic than equal doses of ambient PM2.5 – up to 10 times more harmful.
  • Recent evidence suggests that long-term exposure to PM2.5 may make the coronavirus more deadly.
  • Hospital admissions for respiratory problems, like asthma and pneumonia, rose by 10% during periods when Southern California was covered by wildfire smoke.
  • 1-in-7 US residents on the West Coast experienced at least one day of unhealthy air conditions in 2020. The smoke drifted east creating hazy skies and an oddly vibrant sun on the East Coast.
  • Particles released from burning vegetation in forest fires become more toxic over time – up to four times more toxic a day down the road.

While world leaders tackle the increasing number of fires and climate change, it’s important to make everyone aware of air pollution caused by wildfires and their effects on human health.

This study published by Stanford last week said that “Smoke pollution is particularly challenging to measure, both because it’s difficult to know which portion of PM is from smoke and because we only have pollution monitors at a limited number of locations in the US”.

This is true the world over.

At AirScape, we have the technology to show regional and street-level air quality data in real time. By making the invisible visible we can empower a generation to make informed quality-of-life decisions with reliable air quality data.

If you would like to be part of our air quality revolution to extend airscape.ai to 200 cities across the world, get in touch now.