DOI: 10.5061/dryad.8pk0p2ntf
title: Carbon monoxide exposure inside UK road vehicles: a pilot study

description: Objective To test the following hypotheses:  (i) CO is present
 inside the passenger cabins of road vehicles driven by members of the
 general public in the UK;  (ii) in-cabin CO is due, at least in
 part, to internal exhaust leakage; and (iii) the use of handheld
 dataloggers by laypeople can generate data relevant to the above two
 objectives.
 Design                       Pilot study. Setting                        Two centres: privately-owned cars in Chesham and Amersham, and cars used by engineers at Southern Gas Networks in Epsom. Participants             28 participants entered the study, through online local recruitment (first centre, n=21) and through line management (second centre, n=7), driving 33 vehicles. The study excluded vehicles carrying smokers. Primary outcome measure Parts per million CO, logged continuously during journeys. Mean journey per cent ppm CO was calculated and peak journey ppm CO noted. Methods                    Measurement of CO using mobile-compatible dataloggers. Results                      33 vehicles returned 230 journey logs in all. 20 (61%) of cars logged non-zero CO. Mean all-journey average was 6.629ppm CO. 10 journeys measured ≥10ppm CO at least once. Peak single-journey average CO was 192.174 ppm. Some patterns of CO ingress were suggestive of internal exhaust leakage. Conclusions              This is the first public-engagement UK-based study of CO levels within vehicles. It shows that in-cabin average CO levels are non-zero overall, and in some cases markedly raised.  Chronic low-level CO exposure has a range of harmful effects. In addition to causing hypoxic stress, it contributes to cardiovascular disease, generation of reactive oxygen species, and demyelination of white matter. Pregnant women, the unborn and children are especially vulnerable to its effects, which include gestational-specific harms. Adding in-car air quality measurement to the MOT would benefit public health, alerting vehicle owners, who may be asymptomatic, to raised in-vehicle exhaust levels. Routine MOT air quality testing would have the additional benefit of capturing wider data on the problem, as would larger studies of similar design.
description: Testers measured in-cabin COppm, using the Kane COA1 Carbon Monoxide Detector
 Adapter. Although the maximum range of the sensor was 999 COppm, the app
 supporting the datalogger generated some graphs with readings in excess of
 this level. For calculation purposes, values have been capped at
 999ppm.  Data is
 left in arithmetic form, with right-skewing
 unaltered. Data
 analysis was performed with custom scripts written in
 Lua. Readings from one datalog (see Supplemental
 Material) were set aside due to likely artefactual interference on the
 sensor. 
description: ## Data for the [www.airsafe.london](http://www.airsafe.london) project, a
 pilot study funded for the Carbon Monoxide Research Trust This dataset
 holds a record of each datalog recorded by testers measuring in-cabin
 vehicle COppm. Most datalogs appear in table and graph form, although in
 some instances, logs appear in graph format only. ## Description of the
 data and file structure Each datalog is saved as a separate file. ###
 Formatting of .csv files The .csv files are formatted as follows: The
 first eight lines are human-readable metadata (including the recording
 date and sampling frequency) and summary information. Line 10 contains the
 headers of the main data; line 11 onwards contains the data itself. The
 data is of the form ``` ,x,y,u ``` The datalogging software, which ran on
 a range of mobile phone operating systems, did not generate a
 'u' column in all tables: however, all values show measurements
 made in units of ppm.   where `x` is the sample number, `y` is the
 recorded value, and `u` (where present) is the unit (always `ppm` meaning
 parts per million). ### File naming convention The file naming convention
 uses the following format: \[Anonymised tester number]\_[log
 number]\_[table/graph].  Tables and graphs carrying the same input data
 have the same tester and log numbers. Testers 2 and 6 returned graphs but
 not tables. Where datalogs returned by these testers captured non-zero
 levels of CO, an accompanying .csv file (with duplicate .xlsx file)
 presents the graph data in table form. Where datalogs were generated by
 means of a secondary datalogger as a cross-check, the additional field
 [Easylog] appears after the first three fields set out above. Easylog
 files do not carry a corresponding graph. Data appears in .csv form and is
 duplicated in .txt form. In logs 14_8 and 17_1, levels of CO captured
 exceeded the 999ppm maximum calibration of the datalogger (see section 2.8
 of the write-up). We have accordingly capped these values off at 999ppm,
 adding the additional field [adjusted] after the first three fields.
 Datalogs from testers 3, 4, and 16 subdivide as follows (vehicle numbers
 refer to those listed at Table 1 in the write-up): Tester 3: Log 3_1 shows
 values measured inside vehicle no. 4 Log 3_2 shows values measured inside
 vehicle no. 3 Log 3_3 shows values measured inside vehicle no.5 Tester 4:
 Logs 4_1 to 4_4 (inclusive) show values measured inside vehicle no. 7.
 Logs 4_5 to 4_27 (inclusive) show values measured inside vehicle no. 6.
 Tester 16: Log 16_1 shows values measured inside vehicle no. 19. Log 16_2
 shows values measured inside vehicle no. 20. ### Image files The software
 used also exported image files of the data as graphs. They are included as
 a convenience. Some do not have file extensions, but they are .png files
 and can be opened by any image viewer. ## Sharing/Access information
 Datalogs of note feature in presentations given by the study author as
 part of the [Carbon Monoxide Research Trust 2022 Winter Lecture
 Series](https://youtu.be/wnL9ywnfRjI) and as part of the 2024 NCOAA
 conference. They are also reproduced in the write-up to this study, which
 is to be resubmitted for publication during summer 2024.