Zürich, 08.01.2023
Office for Waste, Water, Energy and Air (AWEL) / Canton Zürich / Switzerland
Stampfenbachstrasse 12, 8090 Zürich
www.zh.ch
Email: luft@bd.zh.ch

This dataset is the result of long-standing measurement campaigns with vehicle "Remote Emission Sensing" (RES) employing a so-called "Remote Sensing Detector" (RSD).

The RSD is a continuously operating optical open-path device with the light beam passing over one road lane at about the height of the tailpipe. The instrument (mainly) measures in the infrared spectrum.
In the RES approach, the RSD captures the increase in pollutant concentration due to an emission plume of a passing vehicle. The increase in pollutant concentration is evaluated against the increase in the plume's carbon dioxide (CO2) concentration. 
Thus, using certain approaches (see Bishop & Stedman, 1996, https://doi.org/10.1021/ar950240x), the pollutant undiluted tailpipe concentration and the vehicle's instant emission relative to its instant fuel consumption can be derived. The result reflects the emission at the instance of measurement under the specific driving conditions and driving behaviour at that site. 
Additionally, vehicle velocity and acceleration at the moment of measurement are recorded. Some general vehicle properties (e.g. fuel type, European emission norm, make) can then be related to the single plume measurement. 
These data do not allow in any way to identify individual vehicles, their owner or driver.
Single plume measurements with RSD are imprecise. However, measuring thousands of plumes, the emissions of representative vehicle categories can be statistically described over a range of typical driving conditions with much better accuracy than for an individual plume measurement.

Since the year 2002, the Canton of Zürich / "Amt für Abfall, Energie, Wasser und Luft AWEL" conducts RSD measurement campaigns during the summer months. The goal of those campaigns is to monitor the real on-road emissions of the fleet of passenger cars and light duty vehicles on the streets in the Canton of Zürich. 
RSD measurements are typically conducted at the same one or two specific locations in the Canton of Zürich.
These measurements are part of the program to monitor the effect of air quality regulation and e.g. help to improve the quantification of real emissions, estimate the percentage of high-emitting vehicles, observe the vehicle ageing effect on the emissions, show the influence of driving conditions and generally support planning and control of air pollution abatement measures.

In the past, focus of data analysis has been laid on NOx emissions. However, RSD also captures (partly only in some years, depending on the instrument model) carbon monoxide (CO), hydrocarbon (HC), opacity, ammonia (NH3).
Results for all of these parameters (if available) are included in the dataset, which begins in the year 2002 with yearly measurement campaigns. Since the year 2022, campaigns are not conducted every single year anymore, but the activity will be going on with a more relaxed schedule.

The AWEL has provided an extended report about the results of the measurement campaigns between the years 2002 and 2021, see: 

	Sintermann, J., Alt, G.M., Götsch, M., Baum, F., Delb, V. (2021): Langjährige Abgasmessungen im realen Fahrbetrieb mittels Remote Sensing (No. v1.4); Kanton Zürich / Amt für Abfall, Wasser, Energie und Luft, Zürich. 
	https://www.zh.ch/content/dam/zhweb/bilder-dokumente/themen/umwelt-tiere/luft-strahlung/luftschadstoffquellen/verkehr/abgasmessungen-rsd/rsd_bericht_2021.pdf

A summary including results from recent measurement campaigns can also be found here (in german): 

	https://www.zh.ch/de/umwelt-tiere/luft-strahlung/luftschadstoffquellen/emissionen-verkehr/abgasmessungen-rsd.html

To understand more about the method, the results and their context, the reader is advised to study the appropriate literature (see e.g. references below). 

The present dataset contains all basic parameters required to start RES analysis. The calculated undiluted tailpipe concentration of measured pollutants are therefore reported (except for CO2, which represents the actual plume-increment). The data have undergone basic plausibility and consistency checks (as described in Sintermann et al., see below). No other filtering has been applied. 
Even though we have undertaken all measures required to appropriately conduct RSD measurements, we cannot guarantee correctness of the data. The user is strongly advised to assess and filter the data appropriately for further analysis. 

The provided data files are structured according to the year of measurement and they will be updated periodically with additional results from future measurement campaigns.
The datasets are published on https://opendata.swiss with a "free" licence, meaning: 

	- the data can be used for non-commercial purposes,
	- the data can be used for commercial purposes,
	- referencing the data source is not required, but recommended: 
		- german: "Amt für Abfall, Wasser, Energie und Luft (AWEL) / Kanton Zürich / Schweiz, Langjährige Abgasmessungen im realen Fahrbetrieb mittels Remote Sensing.
		- english: "Office for Waste, Water, Energy and Air (AWEL) / Canton Zürich / Switzerland, Monitoring real vehicle emissions using remote emission sensing.

The files themselves are comma-separated *.csv files formatted in UTF-8 typesetting; missing data is marked "NA".
They contain the following parameters: 

	- "id": general unique identifying number per measurement record [integer]
	- "date_measured": date of individual plume measurement in format YYYY-MM-DD [string]
	- "site": generalised measurement site identifier in format 'A'..'Z' [string]  
	- "site_roadgrade": measurement site's road grade [double]
	- "site_air_temperature": air temperature at the time of measurement, in degree Celsius, derived from nearby meteorological stations [double]
	- "rsd_model": name of the used RSD model / instrument-number [string]
	- "vehicle_type": general vehicle category 'passenger car' or 'light duty vehicle' [string]
	- "vehicle_fuel_type": vehicle fuel type either 'gasoline' or 'diesel' [string]
	- "vehicle_euronorm": various emission-norms 'Euro1'.. etc [string]
	- "vehicle_make": various vehicle makes [string]
	- "vehicle_model": various vehicle models [string]
	- "vehicle_model_year": year of vehicle model, derived the official certificate of conformity date of homologation (from https://ivz-opendata.ch/opendata/2000-Typengenehmigungen_TG_TARGA/2200-Basisdaten_TG_ab_1995/emissionen.txt, since 2008 if available) [integer]
	- "vehicle_engine_displacement": vehicle engine displacement in ccm [integer]
	- "vehicle_unloaded_weight": vehicle unloaded weight in kg [integer]
	- "vehicle_initial_registration": date of first vehicle registration (if available); in format YYYY-MM-DD [string]
	- "parameter": measurement parameter such as vehicle's instant 'velocity' or 'acceleration' or the calculated undiluted (except for CO2) tailpipe concentrations of 'NO', 'NO2', 'CO', 'HC', 'NH3', 'opacity' [string]
	- "value": record of measured parameter [double]
	- "unit": according unit of the record [string]

Vehicle registration data ("vehicle_*") in the dataset originate from the cantonal Strassenverkehrsamt (in years prior to 2018) and are provided courtesy of the federal Bundesamt für Strassen (ASTRA) (since 2018), authorised for this dataset-publication.
In case a specific vehicle model has been recorded less than 10 times per measurement campaign, i.e. per year, "vehicle_model" has been set NA to make it impossible to indirectly derive information about individual vehicles.

Further references (not complete, in alphabetical order):

	- Bernard, Y., Tietge, U., German, J., Muncrief, R., 2018. Determination of real-world emissions from passenger vehicles using remote sensing data. ICCT.
	- Bishop, G.A., Stedman, D.H., 2008. A Decade of On-road Emissions Measurements. Environmental Science & Technology 42, 1651–1656. https://doi.org/10.1021/es702413b
	- Bishop, G.A., Stedman, D.H., 1996. Measuring the Emissions of Passing Cars. Acc. Chem. Res. 29, 489–495. https://doi.org/10.1021/ar950240x
	- Borken-Kleefeld, J., Bernard, Y., Carslaw, D., Sjödin, A., 2018. Contribution of vehicle remote sensing to in-service/real driving emissions monitoring - CONOX Task 3 report (No. C 295), Commissioned by the Federal Office for the Environment (FOEN), Switzerland. IVL in cooperation with IIASA, University of York, University of Leeds, Kanton Zürich, Opus Remote Sensing Europe, ICCT, Opus Inspectio, Stockholm, Sweden.
	- Borken-Kleefeld, J., Chen, Y., 2015. New emission deterioration rates for gasoline cars – Results from long-term measurements. Atmospheric Environment 101, 58–64. https://doi.org/10.1016/j.atmosenv.2014.11.013
	- Borken-Kleefeld, J., Dallmann, T., 2018. Remote sensing of motor vehicle exhaust emissions (White Paper). ICCT, Berlin.
	- Chen, Y., Borken-Kleefeld, J., 2016. NOx Emissions from Diesel Passenger Cars Worsen with Age. Environ. Sci. Technol. 50, 3327–3332. https://doi.org/10.1021/acs.est.5b04704
	- Chen, Y., Borken-Kleefeld, J., 2014. Real-driving emissions from cars and light commercial vehicles – Results from 13 years remote sensing at Zurich/CH. Atmospheric Environment 88, 157–164. https://doi.org/10.1016/j.atmosenv.2014.01.040
	- Chen, Y., Sun, R., Borken-Kleefeld, J., 2020. On-Road NOx and Smoke Emissions of Diesel Light Commercial Vehicles–Combining Remote Sensing Measurements from across Europe. Environ. Sci. Technol. 54, 11744–11752. https://doi.org/10.1021/acs.est.9b07856
	- Grange, S.K., Lewis, A.C., Moller, S.J., Carslaw, D.C., 2017. Lower vehicular primary emissions of NO2 in Europe than assumed in policy projections. Nature Geoscience 10, 914. https://doi.org/10.1038/s41561-017-0009-0
	- ReMOVES, 2022. Überwachung der Emissionen von Strassenfahrzeugen in der Schweiz. https://www.mobilityplatform.ch/de/research-data-shop?vssmobilityshop_filter_startdate=1900&vssmobilityshop_filter_enddate=2023&vssmobilityshop_filter_active=1&q=1740&vssmobilityshop_filter_sorting=
	- Sintermann, J., Alt, G.M., Götsch, M., Baum, F., Delb, V., 2021. Langjährige Abgasmessungen im realen Fahrbetrieb mittels Remote Sensing (No. v1.4); Kanton Zürich / Amt für Abfall, Wasser, Energie und Luft, Zürich. https://www.zh.ch/content/dam/zhweb/bilder-dokumente/themen/umwelt-tiere/luft-strahlung/luftschadstoffquellen/verkehr/abgasmessungen-rsd/rsd_bericht_2021.pdf
	- Sjödin, A., Jerksjö, M., Fallgren, H., Salberg, H., Parsmo, R., Hult, C., Yahya, M.-R., Wisell, T., Lindén, J., 2017. On-Road Emission Performance of Late Model Diesel and Gasoline Vehicles as Measured by Remote Sensing (No. B2281). IVL Swedish Environmental Research Institute, Stockholm.
	- Tietge, U., Bernard, Y., German, J., Muncrief, R., 2019. A comparison of light-duty vehicle NOx emissions measured by remote sensing in Zurich and Europe (ICCT consulting report). ICCT, Berlin.