Indoor A ir S ampling S trategy

1. IndoorAir SamplingStrategy B.Kotlík, M. Mikešová H. Kazmarová Centre of Environmental Health, Department of Air Hygiene National Institute of Public Health, Šrobárova 48, Prague 10, 10042, Czech Republic web : http://www.szu.cz

2. Introduction • indoor air affects human health; this effect changes as society develops and lifestyles change; • inhalation exposure is determined by pollutant concentrationand 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.

3. Exposure scenarios reveal… … that we spend 2–3 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.

4. Implemented phases ofindoor air monitoringin permanent residential dwellings Around 100 dwellings measured in each of three phases (1994–1998, 1999–2001 and 2002–2003). • 1994–1998 description of sources and concentrations in the indoor environment (target group families with children of pre-school age); • 1999–2001  measurement and description of health in a sample group (pre-school children), associated studies - description of basic anthropogenic (weekly) cycles and for NO2verification of outdoor/indoor relationships; • 2002–2003 description of indoor air quality in dwellings of commonest size in urban areas in The Czech Republic;

5. RegulationNo. 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;

6. Indicator limit Nitrogen dioxide µg.m-3 100 unit PM10dust fraction µg.m-3 150 PM2.5dust fraction µg.m-3 80 Carbonmonoxide µg.m-3 5000 Ozone µg.m-3 100 Asbestos and mineral fibres* No. of fibres.m-3 1000 Ammonia µg.m-3 200 Benzene µg.m-3 7 Toluene µg.m-3 300 Total xylenes µg.m-3 200 Styrene µg.m-3 40 Ethylbenzene µg.m-3 200 Formaldehyde µg.m-3 60 Trichlorethylene µg.m-3 150 Tetrachlorethylene µg.m-3 150 Limits stipulated for indoor air

7. 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

8. 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.

9. 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

10. 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;

11. 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).

12. Air change Ventilation and air-conditioningdisturbs 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.

13. 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 factorsand seasonality (minimum sampling interval of three hours recommended); • sampling interval and frequency should ideally characterize the assessed pollutant and its source(s) – compromise necessary

14. Samplinglocations Breathing zone= locations at least 1 m from walls and 1–1.8 m above floor. • small spaces – 30–50 m2 – sampling in centre of room; • larger spaces – > 50 m2 – divide into parts, preferably wrt ventilation level and mode or purpose of use; • Ceiling height > 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.

15. 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. Accompanying sheet

16. 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.

17. Thank you for listening