Camden’s AirScape helps people protect themselves despite February’s missed high pollution alert

London did not declare a high pollution alert in February despite the fact that, in Camden, the air quality was worse than in January.

Our report on the air pollution trends in Camden, London in February 2023 analysed data from a representative sample of AirNodes from the AirScape sensor network in Camden which measures street-level air quality data in real time. It showed an increase in all major pollutants in February compared to January.

Month/PollutantNO2 in ug/m3O3 in ug/m3PM2.5 in ug/m3
Monthly averages of observed pollutants

The PM2.5 data showed some increased concentration strongly above the average for at least 10 days in February. The periods between the 6th and 9th as well as 13th to 16th were especially bad. The average concentration in the 13th-16th period (31.6 ug/m3) increased three times compared to the average February concentration (10.3 ug/m3). The pollution was of a similar scale that caused the London authorities to raise a high pollution alert on 24th January (18.5 ug/m3) and 25th January (29.5 ug/m3).

The AQI levels reached unhealthy thresholds again, and air quality was very poor on the 14th of February. You could argue that from a health perspective staying home on Valentine’s Day was probably a better decision this year than going on a romantic walk.

The data also revealed two periods of elevated NO2 concentrations on the 6th-10th and 13th-16th of February, with NO2 concentration being clearly higher than the WHO guidelines for 24-hour NO2 average (25 ug/m3).

The ozone concentration showed much higher variability in February compared to NO2. The average concentration of O3 in the last three months (from December to February) remained at similar levels and slightly increased month over month, probably due to increasing sunshine duration. However, periods of low wind speed from the east contributed the most to the low ozone concentration in February. Strong winds from the north that should have reduced the ozone concentration in the city didn’t help in the last days of February due to strong solar radiation. The correlation between wind speed and direction with ozone is very noticeable.

The pollution seems to be correlated with lower temperatures and small wind speeds. Higher wind speed, precipitation, and warm weather have a significant positive impact on lowering PM concentration.

Prof Matthew Johnson, Chief Science Officer at AirScape said Air pollution is one of the most profound issues facing humanity today. Clean air is a human right, just like clean water and safe food.

We saw that pollution in the city was of a similar scale which caused the London authorities to raise a high pollution alert in January.  This, however, didn’t happen in February even though the AQI levels reach unhealthy thresholds again.”

Jorge M Vasquez, Chief Executive Officer at AirScape saidThe significance of everyone being aware of the air they breathe cannot be overstated, as demonstrated by this report. Cities that adopt the AirScape solution are at the forefront of addressing the genuine concerns of their citizens and actively working towards resolving them.”

World Health Organization (WHO) data shows that almost all of the global population (99%) breathe air that exceeds WHO guideline limits and contains high levels of pollutants, with low- and middle-income countries suffering from the highest exposures.

With at least 40,000 premature deaths each year in the UK due to air pollution, toxic air is a known contributor to cancer, heart disease, strokes and asthma. Causing over 20x more deaths than road traffic accidents[i], poor air quality costs society, businesses and our NHS services more than £15 billion a year. To reflect the increasing scientific evidence of the harm to health caused by toxic air, the WHO sharply reduced its guideline limits for air pollution last year.

AirScape, in partnership with Camden Council and The Camden Clean Air Initiative, installed 229 AirNode air quality sensors across the borough of Camden in London to capture hyper-local air quality data every minute, to map the problem in real time. The ground-breaking network provides 45 times more spatial resolution and refreshes 60 times more regularly than existing air quality reference stations. They aim to replicate the model across London and major cities worldwide to enable real action on air pollution.

Data is freely available on the AirScape web platform, at, to enable individuals, businesses and local authorities to make quality-of-life decisions that improve air quality for all. The data generated from the network can be used in a myriad of ways, enabling the public to choose less polluted routes from A-to-B, feeding into local traffic management policy and providing NHS Trusts and schools with information to help raise awareness of air pollution and protect vulnerable communities. The future possibilities of how the data can be used are vast and AirScape is aiming to engage with potential partners, clean air groups and councils to explore future collaboration.

This report serves as a reminder that air pollution is still a major problem, and we need to take measures to address it. The report provides scientifically advanced air quality information that is easily accessible to the public. The findings will be used to improve air quality in Camden, London, and other cities around the world.

Based on the data gathered by the Camden Network in London, February was another eventful month regarding air pollution.  Of greater concern is that London did not declare a high pollution alert in February, despite the air quality being worse than it was in January.

NO2 data exhibited stable daily patterns, with of slight increase in all pollutants compared to January. The concentration of NO2 was higher than WHO guidelines throughout January.

Ozone is slightly increasing each moth due to increased sunshine duration. 

We saw increased PM2.5 concentration strongly above the average for at least 10 days in February. The highest PM concentration, three times higher than average for the month, were between 6-9th February and 13-16th. 

Pollution levels of a similar scale that prompted a high pollution alert by London authorities on 24th January was seen again in February – but without another alert. Live data from showed in real time the increased pollution over the Camden borough and could have a real impact on those more vulnerable to air pollution (Fig. 7 and 8). Figure 7 shows that Valentines Day was not the best time for a romantic walk.

Read February’s full report here

Based on the data gathered by the Camden Network in London, January was another eventful month regarding air pollution. 

NO2 data exhibited stable daily patterns, with of higher concentrations coinciding with cold air and low wind speed in the 2nd half of the month. The concentration of NO2 was higher than WHO guidelines throughout January.

Changes in wind direction and intensity from continental Europe saw Ozone levels showing much higher variability. 

PM showed some moderation in January compared to December. The highest PM concentration was observed between 21st and 26th of January corresponding to the low temperatures in that period.

High pollution in January was also noticed by London authorities. A “high pollution alert” was issued on 24th January following the forecast from Imperial College London. The alert correctly predicted pollution events for the next few days. However, it was late to caution citizens against increased pollution during the weekend (21st and 22nd January). Live data from showed in real time the increased pollution over the Camden borough and could have a real impact on those more vulnerable to air pollution. Figure 7 clearly shows that high PM concentrations were observed already on 22nd of January. This also corresponds well with NO2 data from the same period.

Read the full report here

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, 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.”