Journal of Public Health | Vol. 34, No. 4, pp. 477 –482 | doi:10.1093/pubmed/fds023 | Advance Access Publication 16 March 2012
Carbon monoxide from neighbouring restaurants: the need
for an integrated multi-agency response
C. Keshishian 1, H. Sandle 2, M. Meltzer 3, Y. Young 4, R. Ward 5, S. Balasegaram 2
1
Centre for Radiation, Chemical and Environmental Hazards, Health Protection Agency, Buckingham Palace Road, London SW1W 9SZ, UK
North East and North Central London Health Protection Unit, Health Protection Agency, Buckingham Palace Road, London SW1W 9SZ, UK
North West London Health Protection Unit, Health Protection Agency, 61 Colindale Avenue, London NW9 5EQ, UK
4
South West London Health Protection Unit, Health Protection Agency, Springfield University Hospital, 61 Glenburnie Road, London SW17 7DU, UK
5
Pollution Team, Regulatory Services, London Borough of Ealing, 14-16 Uxbridge Road, London W5 2HL, UK
Address correspondence to C. Keshishian, E-mail: [email protected]
2
3
A B S T R AC T
Background Carbon monoxide (CO) is a colourless, odourless toxic gas produced during incomplete combustion of carbon-based fuels. Most
CO incidents reported to the UK Health Protection Agency (HPA) are due to faulty gas appliances, and legislation exists to ensure gas
appliances are properly installed.
Methods We present three CO poisoning incidents of unusual origin reported to the HPA. In each, residents living above restaurants were
poisoned after workers left charcoal smouldering overnight in specialist or traditional ovens whilst ventilation systems were turned off. This led
to production of CO, which travelled through floorboards and built up to dangerous concentrations in the flats.
Results Working with local authorities, these incidents were investigated and resolved, and work was conducted to prevent further
occurrences.
Conclusions The novel nature of these CO incidents led to delays in recognition and subsequent remedial action. Although previously
undescribed, it is likely that due to the number of residences built above restaurants and the rising popularity of traditional cooking methods,
similar incidents may be occurring and could increase in frequency. Multi-agency response and reporting mechanisms could be strengthened.
Awareness raising in professional groups and the public on the importance of correct ventilation of such appliances is vital.
Keywords air quality, public health
Introduction
Carbon monoxide (CO) is a colourless, odourless gas that
can be toxic when inhaled. At low levels, chronic CO poisoning can produce symptoms of lethargy, flu-like illness
and impaired memory; at high levels, acute CO poisoning
can produce headaches, nausea, vomiting and may lead to
loss of consciousness and death.1
CO is produced when carbon-based fuels burn with insufficient oxygen. It is recommended that all domestic gas,
solid fuel and oil-fired appliances be serviced annually by
qualified engineers to ensure they are burning correctly and
have adequate ventilation to prevent production of CO.2
However, CO can travel through any cavities or gaps in
the walls and floors separating properties, therefore residents
of neighbouring properties may be at risk of CO poisoning
from appliances in neighbouring premises for which they
have no maintenance or servicing responsibilities.
We present three incidents reported to the Health
Protection Agency (HPA), which have not previously been
described, that occurred within a few months of each other
C. Keshishian , Environmental Public Health Scientist
H. Sandle , Health Protection Nurse
M. Meltzer , Consultant in Communicable Disease Control
Y. Young , Consultant in Communicable Disease Control
R. Ward , Pollution (Technical) Team
S. Balasegaram , Consultant in Communicable Disease Control
# The Author 2012, Published by Oxford University Press on behalf of Faculty of Public Health. All rights reserved.
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in 2008 – 09, where unusual activity in restaurants led to CO
affecting local residents.
Incidents
Incident one
Shortly after its installation, the CO alarm in a flat began
sounding in the early hours of the morning. Registered gas
engineers could find no fault with the gas appliances in the
flat or with the alarm itself. Over the next few months, the
alarm continued to sound and the presence of CO was confirmed in the flat by engineers. The resident and a guest
reported headaches and lethargy and consulted their general
practitioner. Eventually, the source was traced to the Indian
restaurant below the flat, where the charcoal-burning
tandoor oven was apparently left smouldering overnight
while the ventilation system was turned off.
Five months after the initial alarm activation, the gas
engineers recommended that the flat’s resident inform and
seek assistance from the local authority (LA) pollution team.
The LA confirmed the presence of CO in the restaurant
and issued an Abatement Notice prohibiting the use of the
oven without extractor fans. Unfortunately, the CO alarm
continued to activate, culminating in an incident where the
residents found it difficult to rise from bed in response to
the alarm and had to call the emergency services, who confirmed that the charcoal had been left burning.
Immediate action to seize the oven by the LA could not
be taken until witness statements had been provided by the
emergency services describing the violation of the
Abatement Notice. Whilst awaiting these, the pollution team
asked the HPA for public health advice. Advice was given
regarding environmental levels of CO, symptoms of CO intoxication and a recommendation was made to check neighbouring properties, especially for vulnerable residents. HPA
advice was distributed to local residents. Occupants of the
flat were advised to visit their doctor and if they felt ill
again, to have a blood test so that carboxyhaemoglobin
(COHb) levels could be assessed. The residents were also
advised to move out of the flat until enforcement action
could be taken.
The LA served an Improvement Notice on the restaurant
and obtained a warrant to seize the oven using legislation
from the Environmental Protection Act 1990 (Part III).
Following this, the owner replaced the oven with a gas-fired
oven, approximately 3 weeks after the final alarm activation.
In response to the incident, the LA risk assessed similar
appliances in other restaurants in the borough. Five ovens
were identified in 40 restaurants; in two cases the appliances
were used without an extractor fan in operation and notice
was served on these premises and CO monitors installed in
the flats above. The LA is applying for funds to enable
monitors to be installed in restaurants with similar ovens
and to supply CO alarms to vulnerable properties.
Incident two
Over a 3-month period, residents in a flat were repeatedly
alerted to elevated CO levels in their property by their CO
alarm. The LA confirmed levels of 45 ppm CO in the flat
but no source could be found within the property. A longstanding odour nuisance complaint suggested that the restaurant below should be considered as a source, but the gas
oven was in working order.
The investigating LA officer provided residents with
written copies of HPA advice,3 advised ventilation of the
property if the alarm sounded and to consult a doctor if
they experienced any symptoms. Having confirmed that the
CO alarm was working correctly and that the situation was
still unresolved, the LA officer was concerned about longterm exposure to CO and contacted the HPA for advice.
The HPA reviewed the sampling results from the flat and
concluded that although not hazardous to health in the
short term, concentrations of 45 ppm over 8-h periods or
longer are above the UK air quality standard of 10 ppm for
8 h3 and remedial action should be taken.
Monitoring equipment was installed by the LA in both
the restaurant and flat. Figure 1 shows the close correlation
between CO concentrations in the two premises, with the
increase in the restaurant closely followed by an increase in
the flat. On a later visit to the restaurant, the officer noticed
the presence of a charcoal-fired tandoor oven. Aware of incident one, the HPA suggested the two LAs liaise.
The LA officer was able to demonstrate that the tandoor
oven was indeed the source. As in incident one, the extractor system had been turned off overnight and the charcoal
left smouldering, with CO levels in the restaurant peaking in
the early hours of the morning (Fig. 1). The oven was
replaced with a gas oven and subsequent monitoring confirmed that significant levels of CO were no longer being
produced.
Incident three
Two housemates living in a flat above an Asian restaurant
felt unwell and alerted paramedics attending a different call
nearby. Suspecting CO poisoning, the ambulance and fire
services evacuated a further seven people from two other
flats above the restaurant. All were taken to hospital and the
HPA informed.
CA R B O N M O N OX I DE F RO M NE I G H B O U R IN G R E S TAU RA N T S
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70
60
Flat
Carbon monoxide (ppm)
Restaurant
50
40
30
20
10
15:19
18:49
22:19
01:49
05:19
08:49
12:19
15:49
19:19
22:49
02:19
05:49
09:19
12:49
16:19
19:49
23:19
02:49
06:19
09:49
13:19
16:49
20:19
23:49
03:19
06:49
10:20
13:50
17:20
20:50
00:20
03:50
07:20
10:50
14:20
17:50
21:20
0
Day 1
Day 2
Day 3
Day 4
Time
Day 5
Day 6
Fig. 1 Correlation between the measured carbon monoxide concentrations in restaurant and flat above, incident two.
COHb levels ranged from 7.4 to 21.6%, the normal
range for non-smokers is usually between 1 and 2%;1 residents in flats closer to the restaurant had higher levels than
those on higher floors. Residents from all three flats
reported having felt ill for 3 – 6 weeks, one had visited their
GP with a flu-like illness, suggesting that the flat occupants
may have been exposed to CO for several weeks. None of
the flats had CO alarms.
The LA established that the heating and cooking devices
in the flats were electric and the CO source was identified as
the charcoal-burning grills in the restaurant, which had been
left on overnight while the extractors were turned off.
Measurements taken by the LA next to the active grill were
150 and 500 ppm CO, and a Prohibition Notice was served
on the oven. A safer gas-fuelled grill was installed and CO
alarms were fitted to all three flats. The LA visited all of the
restaurant chain’s premises and other restaurants with
charcoal-burning appliances in their borough.
Discussion
Main finding of this study
This case series describes three incidents of CO poisoning
in residential properties. Although some residents had taken
precautions—regularly servicing gas boilers, installing CO
alarms and consulting healthcare professionals—in each
case they were exposed to CO from activities in neighbouring properties. The restaurants used charcoal-burning
tandoor ovens or grills, which were in working order,
however by leaving these burning overnight without adequate ventilation, CO was produced, travelling through wall
and floor spaces to reach significant levels in neighbouring
domestic properties. These unusual scenarios led to delays
in recognition of the problem, reporting and intervention by
appropriate authorities.
What is already known on this topic
CO poisoning incidents in England and Wales that are
reported to the HPA mostly occur in residential properties,
due to faulty installation of gas-fired central heating appliances or the inappropriate use of outdoor heating or
cooking appliances indoors. There is existing legislation covering the installation, maintenance and use of gas appliances
in both residential and workplaces;4,5 there is currently no
similar legislation covering non-gas appliances. Residential
landlords and restaurants owners are not required to install
CO alarms, although it is strongly recommended by the
Health and Safety Executive (HSE) that an audible alarm
meeting British or European standards (BS Kitemark or
EN 50291) is installed in homes and workplaces.
The HPA and LAs work collaboratively in response to
CO incidents, with the HPA providing toxicological and
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public health advice, and the LA using their legislative
power to act to prevent further harm. However, property
owners are expected to take responsibility for ensuring
correct maintenance and use of appliances, and complying
with recommendations and notices.
A literature review of scientific journals and grey literature
using the search terms ‘carbon monoxide’ and ‘restaurant’
or ‘takeaway’ identified risk to workers from CO and
cooking appliances, with charcoal identified as a particular
risk.6,7 Papers associated with public exposure to CO from
restaurants are few; in 1996, mass CO poisoning of diners
from traditional charcoal cookers occurred in Réunion,8 and
Health Protection Scotland recently published results of an
investigation into the link between odour complaints from
takeaway restaurants and CO gas.9
What this study adds
The need for integrated multi-agency response
In incident one, there was a delay of 8 months from the
initial identification of high levels of environmental CO until
the necessary action was taken. This was partly due to the
delay in other agencies/professionals informing the HPA
and LA.
The LA and HPA can only take action if they are aware
or informed of an incident. Registered gas safety engineers
are expected to inform relevant authorities if they identify a
problem during an inspection,10 but this system could be
strengthened. Moreover, gas engineers may not necessarily
confirm the presence of CO or investigate non-gas sources,
meaning that some CO incidents are missed entirely. An opportunity for identification of CO poisoning was also
missed in incident three by the general practitioner; the nonspecific symptoms of CO poisoning are often misdiagnosed
and an algorithm to aid diagnosis among medical practitioners is available.11
Figure 2 shows some of the agencies involved in CO incident response. The response can be complex and there is
potential for notifying or preventative actions to be overlooked; a key role of the HPA is to coordinate response and
ensure a comprehensive, timely resolution. The CO Action
Card lists the recommended steps for HPA staff and gives
an overview of the roles and responsibilities of different
organizations.12 It is notable that in incident two, the HPA
Acute CO incident
Fire and rescue
service
Ambulance service
Fuel engineers
Health Protection
Agency
Health & Safety
Executive
Local authority
NHS (GP, hospital,
smoking cessation)
Chronic CO incident
Fig. 2 The main communication routes for reporting CO poisoning incidents in England. Reporting is not always mandatory and additional routes and
organizations may exist. NHS, National Health Service, GP, general practitioner.
CA R B O N M O N OX I DE F RO M NE I G H B O U R IN G R E S TAU RA N T S
acted as a central information point, allowing experience to
be shared between different LAs.
Carbon monoxide can travel between properties
CO poisoning may not be suspected initially if investigation
is limited to appliances in the household of the affected
case(s). Regular servicing of boilers and household appliances, though important, will not offer protection from CO
that has originated in neighbouring properties; indeed, in
two of the three incidents, residents were only alerted to the
danger by their CO alarms. This emphasizes the importance
for emergency responders at a CO incident to ensure that
occupants of neighbouring premises are safe.
Clarification of legal and enforcement action
In incident one, the delay was aggravated by difficulties
associated with monitoring compliance with the LA
Improvement Notice conditions. Such breaches occurred in
the early hours of the morning, making evidence-gathering
challenging. Production of significant levels of CO can be
difficult to prove as production may be intermittent or, as
time elapses, properties will have been ventilated and COHb
metabolized.
Understanding the different legislative options available
and evidence required for each is the responsibility of the
regulating bodies, but this knowledge is also important for
public health practitioners who can assist the LA and HSE.
In these incidents, legislative options included the
Environmental Protection Act 1990 (Part III) and the
Health and Safety at Work Act 1974.
In the light of these cases, the HPA, in discussion with
regulatory bodies, is investigating how to clarify the legal
requirements on the use of traditional non-gas ovens.
Indeed, the Chartered Institute of Environmental Health
has recently recommended that new legislation is introduced
so that installation of CO alarms is mandatory in all residential premises adjacent to commercial food outlets.13 In addition, the UK 2011 All Party Parliamentary Gas Safety
Group parliamentary enquiry has received this evidence and
highlighted the requirement for the HSE and local authorities to raise awareness of CO in the catering industry due to
these incidents.14
Prevention, awareness raising and training would be
useful
As CO poisoning is preventable, it is a priority to raise
awareness of the above issues in all the organizations
involved, including gas engineers, restaurant owners and
members of the public.
481
In all three incidents, the ovens were in working order
but were being used inappropriately, with ventilation systems
turned off overnight. There is therefore a need for the regulatory bodies to ensure that users of charcoal ovens are
aware of the need for adequate ventilation at all times. This
could be done by LA food hygiene officers who regularly
inspect restaurants, for example.
Targeted cross-agency training for professionals may
improve the efficiency of the response through highlighting
and identifying the roles and expertise of each agency. The
HPA runs CO Workshops annually across England, which
are well-attended by EHOs, public health practitioners,
emergency responders (fire, ambulance) and policy-makers
such as the HSE and Department of Health. The incidents
described here provide useful learning scenarios.
Limitations of this study
This case series describes three incidents reported to the
HPA. Due to the delays in notification to the HPA and to
the number of agencies involved, some facts and timelines
presented may be distorted, although every effort has been
made to ensure these are accurate. This again emphasizes
the importance of early notification and close partnership
working between all the organizations.
Conclusions
Residential flats are frequently built above restaurants in urban
areas. It is therefore possible, and indeed likely, that similar
CO poisoning events are occurring that enforcing bodies and
the HPA are unaware of. Traditional-style ovens are becoming
fashionable in UK restaurants as people seek an authentic
gastronomic experience. In addition to tandoor ovens, other
ethnic ovens have been implicated in CO safety issues as
many do not meet CE (European Directive) standards.15
The current emphasis on making buildings more energy
efficient makes it easier for indoor gases to build up and
travel through any gaps or cavities within walls and floorboards. Legal requirements for the installation of CO alarms
in restaurants and mandatory ventilation of charcoal-burning
ovens could be considered to prevent further similar incidents occurring.
Although two of the incidents presented regarded lowlevel, chronic CO poisoning, the third case of acute intoxication reported from an emergency department demonstrates
how dangerous unrecognized and uncontrolled production
of CO can be. Raising awareness of these issues in all of
the organizations involved and members of the public is a
priority.
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Acknowledgements
6 Madani IM, Khalfan S, Khalfan H et al. Occupational exposure to
carbon monoxide during charcoal meat grilling. Sci Total Environ
1992;114:141 – 7.
The authors would like to thank Graham Guthrie (London
Borough of Wandsworth), Andrew Pedley (London
Borough of Ealing) and David Ball (London Borough of
Westminster) for their contributions to the article.
7 Ojima J. Generation rate of carbon monoxide from burning charcoal. Ind Health 2011;49(3):393 –5.
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