Indoor Air Sampling Strategy

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IndoorAir SamplingStrategy

• B. Kotlík, M. Mikeová H. Kazmarová
• Centre of Environmental Health, Department of Air
  Hygiene
• National Institute of Public Health, robárova
  48, Prague 10, 10042, Czech Republic
• web http//www.szu.cz

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Introduction

• indoor air affects human health this effect
  changes as society develops and lifestyles
  change
• inhalation exposure is determined by pollutant
  concentration and time spent in environment
• health protection and exposure assessment is
  based on identifying and objectivizing factors in
  the indoor environment
• the aim is to estimate health risks and take
  measures to mitigate them.

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Exposure scenarios reveal

• that we spend 23 hours (12) of the day
  outdoors and the rest of the time (88) indoors
  more than 50 of this at home (over 12 hours a
  day), 30 at work (about 8 hours a day) and the
  remainder in vehicles and in various other
  buildings.

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Implemented phases of indoor air monitoring in
permanent residential dwellings

• Around 100 dwellings measured in each of three
  phases (19941998, 19992001 and 20022003).
• 19941998 ? description of sources and
  concentrations in the indoor environment (target
  group families with children of pre-school age)
• 19992001 ? measurement and description of health
  in a sample group (pre-school children),
  associated studies - description of basic
  anthropogenic (weekly) cycles and for NO2
  verification of outdoor/indoor relationships
• 20022003 ? description of indoor air quality in
  dwellings of commonest size in urban areas in The
  Czech Republic

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Regulation No. 6/2003 Coll. stipulating health
limits for chemical, physical and biological
indicators for the indoor environment of
habitable rooms in certain buildings

• applies to educational facilities, universities,
  open-air schools, convalescent homes, preventive
  healthcare facilities, social care homes,
  accommodation facilities, commercial premises and
  public assembly buildings
• assessment of average (Avg) 1-hour concentrations
  of pollutants detected in ameasured interval. The
  measured interval must cover potential exposure
  and concentration variability of pollutants
  detected

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Limits stipulated for indoor air
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Reasons for measurement

• to check compliance with stipulated limits
  (legislation) or recommended levels
• to check corrective measures (building
  alterations)
• to determine user exposure (to find causal links
  between indoor air pollutants and adverse effects
  on health observed by users i.e. complaints)
• to assess or estimate health risks

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• defined sampling has been resolved quite
  successfully at various levels and is being
  incorporated into various standards and codified
  analytical procedures
• representative samples are routinely required for
  assessment and interpretation of results but
  sampling strategy for ensuring representative
  samples has not yet been defined.

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The reasons are clear

• air (including in indoor environment) is dynamic
  and, in terms of concentration, unstable mixture
  of gases and aerosols
• levels measured are always strongly affected by
  numerous factors (distribution of sources,
  configuration, microclimate and even climatic
  factors) and by activities in the measured space
  hence also by ... measurement itself

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Specific properties

• pollutants monitored in indoor air often also
  have major sources in outdoor air
• transport of pollutants between indoor and
  outdoor environments
• personal or passive dosimeters are, despite their
  advantages, unusable in some cases (by children,
  in dusty environments, etc.)
• unlike analysis, sampling cannot be repeated

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Limitations and interferences

• shape of space and distribution of potential
  sources, air change, nature and regime of
  sources, users and their activities, type and use
  of space measured
• influence of mode of activity and use of internal
  environment (noise, occupation of the space) and
  levels measured
• users of the space measured
• microclimatic parameters (temperature, relative
  humidity, air pressure and air change and flow
  rate data).

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Air change

• Ventilation and air-conditioning disturbs
  equilibrium either by dilution or transport.
• sources located in indoor environment only (user
  activity, building materials or room
  furnishings), worst possible conditions, do not
  disturb equilibrium
• when assessing exposure of users, need to
  maintain the standard (normally used) ventilation
  regime before and during measurement
• controlled air exchange - start measuring only
  after time estimated for at least three air
  changes in room
• 10 rule.

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Measurement time, sampling interval, measurement
frequency

• measurement time should cover
• temporal variability of concentrations of
  pollutants monitored caused by source activity
  regime
• anthropogenic effects (daily cycle, user
  activities)
• microclimatic factors and seasonality (minimum
  sampling interval of three hours recommended)
• sampling interval and frequency should ideally
  characterize the assessed pollutant and its
  source(s) compromise necessary

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Sampling locations

• Breathing zone locations at least 1 m from
  walls and 11.8 m above floor.
• small spaces 3050 m2 sampling in centre of
  room
• larger spaces gt 50 m2 divide into parts,
  preferably wrt ventilation level and mode or
  purpose of use
• Ceiling height gt 10 m - height gradient
• air-conditioning or controlled air circulation -
  differential measurement at inlet and outlet to
  assessed space can be used
• avoid locations close to constant or ad hoc heat
  sources, draughts, dead spots, cool or sunny
  locations in measured space.

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Accompanying sheet

• Not used merely to describe measurement
  conditions
• but
• primarily as a basic summary of information for
  interpreting results, for seeking causes and for
  proposing corrective measures.

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Conclusions

• to evaluate the effects of pollutants occurring
  in indoor air, we need representative data which,
  in combination with all the available
  information, will enable us to interpret the
  levels measured
• it is unrealistic to expect detailed and
  prescriptive sampling procedures to be
  stipulated
• the reality involves and always will involve
  seeking compromises between requirements and
  capabilities
• our goal has been to provide adequate resources
  for decision-making during sampling and
  measurement in the internal environment -
  resources that will enable workers to justify and
  defend their choice of procedure in each
  particular case.

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Thank you for listening