of PM2。5 in indoor air when operating wood-burning fireplace ovens (Ward and Noonan, 2008; Noonan et al。, 2012; McNamaraet al。, 2013)。 Carvalho et al。 (2013) have studied the formation of ultrafine particles from wood-burning stoves。With fine and ultra-fine particulate matter being increasingly in the focus of public discussion recently, the German Federal Environment Agency published a guidance value for evaluating fine particulate matter (PM2。5 fraction) in indoor air of 25 lgm_3 (Salthammer,2011)。 This directly concerns wood-burning fireplace ovens as potential sources of particles (Jalava et al。, 2010)。 Consequently,WKI carried out a study with a total of seven test series in living rooms with wood-burning  fireplace ovens。 The results  are presented in this paper and discussed with regard to current indoorair hygiene criteria。 Another paper reports the effects of ethanol fireplaces on indoor air quality (Schripp et al。, 2013)。

2。 Materials and methods

2。1。 Selection of fireplaces

The effects of wood-burning fireplace ovens on indoor air quality were investigated on-site in private homes with such an oven。Seven households in detached houses in the greater Braunschweig area were involved in the investigations。     Braunschweig is located in the south east part of Lower Saxony (52_230N, 10_560E)。 Table 1 shows details of the rooms and ovens examined。 The air intake was from the air in the room in each case except for oven 3, which had an intake from the outdoor air。 The investigations began in the 2012/2013 heating period。 The test samples were taken right though into March 2013。 In order to detect whether the fireplace was affecting the indoor air quality, it was necessary to take air samples before the oven was used as well as during use。 Fine particulate matter (PM2。5) and polycyclic aromatic hydrocarbons (PAH) are typical products of wood combustion, but they are also present in the outdoor air and can enter the building during ventilation。These parameters were therefore also measured in the outdoor air close to the building in order to make a comparison。 were compared with those of reference compounds。 Details of calibration procedures are given in Massold et al。 (2005)。

Aldehydes/ketones: Hydrazones are formed from 2,4-dinitrophenyl-hydrazine (DNPH) by nucleophilic addition to the carbonyl group, followed by elimination of water。 For sampling, air is sucked for 40 min through cartridges (Supelco) coated with DNPH at a flow rate of 1。0 l min_1。 Elution of the sampled cartridge and HPLC analysis is performed as described in Salthammer and Mentese(2008)。

Total volatile organic compounds (TVOCPAS): Photo acoustic detector (INNOVA 1312) at 3。4 lm (2950 cm_1) with a flow of 140 ml per sample and a time resolution of 60 s (flow rate 175 ml min_1) against the response factor of propane。

Carbon dioxide (CO2) and carbon monoxide (CO): Measured simultaneously with TVOCPAS by use of the same photo acoustic detector (INNOVA 1312) at 4。4 lm (2270 cm_1) and 4。7 lm (2150 cm_1) respectively。Nitric oxide (NO) and nitric ioxide (NO2): Chemiluminescence technique (Horiba, APNA-370) with a flow rate of 0。8 l min_1 and a time resolution of 60 s。 This device uses a dual measurement principle and a subtraction calculation method。Particles: The concentration and size distribution monitoring for ultra-fine particles was performed using a TSI Model 3091 Fast

Mobility Particle Sizer (FMPS), which measures particle number concentrations in the size range of 5。6–560 nm in 32 logarithmically spaced channels。 Scans are acquired with a time resolutionof Dt = 1 s。 In addition, particles of sizes between 0。3 and 20 lm were measured using an additional optical particle counter (OPC)(Grimm Technologies Inc。, Dust Monitor 1。108)。 With a scanning time of 6 s, 15 different size classes were covered。 For sampling of PM2。5 on quartz filters (Whatman EPM2000) a low volume sampler (Derenda) was used。 The sampling time was 24 h at flow rate of 2。3 m3 h_1 (55。2 m3 total volume)。 Before and after sampling, the filter was conditioned at 23 _C and 50% relative humidity。 The mass on the filter was determined gravimetrically by use of a Mettler Toledo MX5 balance。Benzo[a]pyrene (BaP): collected on polyurethane foam (spiked with deuterated internal standard) and glass fiber filters。 The sampling volume was 10 m3 (KFN Neuberger membrane pump)。 Foam and filter were extracted in toluene and after cleanup BaP was