Abstract

Locations where relationships between ambient particle concentrations and health outcomes have been observed share combustion processes as a common particulate source. Since individuals spend the majority of their time indoors, fine particles generated in indoor combustion processes (cooking, smoking, woodburning) are also important for health effects assessment.

We evaluated a continuous monitor, a portable nephelometer, for the assessment of indoor particulate, produced in combustion processes. Simultaneous sampling with PM₁₀ and PM_2.5 impactors was undertaken to determine the relationship between particle light scattering coefficient (_sp) and particle mass concentration in field and environmental chamber settings. Chamber studies evaluated nephelometer measurements of environmental tobacco smoke and particles produced from toasting bread and frying foods. The nephelometer technique was applied to the assessment of particulate levels in restaurants and bars with different smoking restrictions and in residential kitchens where fried foods were prepared.

_sp and particle mass were highly correlated (r² values of 0.47 - 0.99) over a wide range of concentrations (7 - 381µg/m³). Different _sp vs. particle mass slopes were observed for the different sampling environments, reflecting the influence of particle composition on light scattering. However, in similar indoor environments, the relationship between particle light scattering and mass concentration was consistent enough to use independent nephelometer measurements as estimates of mass concentrations.Indoor concentrations were significantly higher in establishments with no smoking restrictions ( mean PM_2.5 concentration = 190 µg/m³, range 47 - 253) than in restaurants with partial smoking restrictions (mean PM_2.5 concentration = 57 µg/m³ , range: 11 - 163). Cooking was also found to be a significant source of indoor particulate asindicated by measurements in non-smoking restaurants (mean PM_2.5 concentration = 38 µg/m³, range: 7 - 65) and in residential kitchens during cooking periods (mean PM_2.5 concentration = 75 µg/m³, range: 7 - 201). In each environment, 5 minute average peak PM_2.5 concentrations above 400 µg/m³ were observed. These data indicate the potential for high particulate exposures associated with cooking and environmental tobacco smoke indoors.

Introduction

In the diverse locations where associations between ambient particle concentrations and adverse health outcomes have been observed, one common feature of the particulate sources are combustion processes. Since individuals spend the majority of their time indoors, fine particles generated in indoor combustion processes (cooking, smoking, woodburning) are also important for health effects assessment. The nature and magnitude of indoor particle exposures can change rapidly because of the multiple sources and differences in ventilation. When used with filter sampling, continuous monitoring of fine particles improves exposure assessment by characterizing the impact of time-varying indoor sources. An example of a real-time measurement device that is very easy to use, is the nephelometer, which measures the light scattering extinction coefficient (_sp) of the particles in the air every second.

[...]

Here we report on more measurements of the relationship between particle mass and light scattering for environmental tobacco smoke (ETS) and cooking particulate in chamber and field settings. In chamber experiments particles were produced from single sources: cigarettes, from burned toast and from frying foods. Measurements of PM₁₀, PM_2.5 and light scattering were then made in indoor environments where the major source of particles were from smoking and cooking: restaurants, bars and residential kitchens. As an application of this approach to particle exposure assessment, we evaluated the impact of different smoking restrictions on indoor particulate levels.

[...]

Measurements in restaurants, bars and residential kitchens

Five to six hour measurements were made in 20 restaurants and bars in Vancouver B.C. and vicinity. The restaurants were divided into 3 categories based on their smoking policy: 5 non- smoking restaurants, 11 restaurants with both a no-smoking (regulations require at least 40% of seating to be non-smoking) and a smoking section (restricted smoking), and 4 bars (with food service) where smoking was unrestricted. Indoor measurements were made for approximately 6 hours with two inertial impactors (PM₁₀ and PM_2.5) and a nephelometer, all placed on a table. In the restaurants with both a smoking and no-smoking section, the measurement devices were situated in the no-smoking area, as close as possible to the smoking area, in order to obtain a worst-case situation for a non-smoking customer. For every restaurant/bar, the room-dimensions were measured and, every 5 minutes the number of customers and the number of burning cigarettes were counted. Similar procedures were used in residential kitchens, although sampling durations were shorter. In kitchens, samplers were operated for 15-30 minutes prior to cooking, during the cooking period and for at least 30 minutes after cooking ceased. Sampling durations were 1.5 - 3 hours and cooking periods were 24 - 54 minutes.

[...]

Conclusions

We also found cooking to be a significant source of indoor particulate as indicated by measurements in non-smoking restaurants (mean PM _2.5 concentration = 38 µg/m³, range: 7 - 65) and in residential kitchens during cooking periods (mean PM_2.5 concentration = 75 µg/m³, range: 14 - 201). In all types of restaurants and in the kitchens, 5 minute average peak PM_2.5concentrations above 400 µg/m³ were observed. Very few studies have commented on the impact of cooking. Kamens and colleagues reported that cooking was the most important fine particle-generating activity in non-smoking homes⁸, while Ozkaynak and colleagues indicated that in homes where cooking took place, cooking accounted for 25% of the indoor PM_2.5 mass⁹. These data indicate the potential of high particulate exposures associated with cooking and environmental tobacco smoke indoors.