A total of 4500 complete survey responses were collected. This sample size had a margin of error of ±1.5%, at a 95% confidence level for the overall survey. The margin of error for individual questions where a subgroup of the sample is considered was higher, but no more than ±4.7% (i.e., the estimated population response rate was 4.7% above or below the sample response rate with a 95% probability). These precision bounds assume no significant biases in the respondents relative to the entire population.

Despite efforts to recruit a representative sample across all key demographic characteristics, there was some degree of over or under-sampling of socioeconomic groups that required adjustments. In comparison with the 2016 Census, people who were low-income ($19,999 and under), lived in a rented home, or lived in an owned attached house or apartment were over-represented by 4–15%; while people who had an annual income above $60,000 or lived in an owned or detached house were under-represented by 5–12%. Therefore, adjustments have been applied to household income, house type, rental vs. owner occupancy, region, age, and gender. Table 1 shows the raw and adjusted survey response distribution by demographic and housing characteristics. Figure S1 shows the percentage of survey respondents and the 2016 Canadian Census population by province.

Most results in this section and subsequently are presented with simple language that treats responses as accurate. More precise language is used for parameters thought potentially or shown previously to be subject to recall or self-reporting biases, for example, how often a range hood is used when cooking [48].

The majority of respondents had electric cooktops (86%) and ovens (91%) with almost all others having natural gas appliances. The breakdown of cooking fuels was similar to that reported in the Canadian Human Activity Pattern Survey 2, where 84% of respondents used electric and 16% used natural gas cooktops [56]. The percentage of households using natural gas for cooking was much lower in comparison to the U.S. (38%) [57]. Less than 1.5% of respondents reported using other fuels for cooking, including propane, butane, and wood.

The top four cooking appliances that participants reported using at least three days a week were cooktop (by 90% of respondents), microwave (79%), toaster (58%), and oven (52%) (Fig. 1). The most frequently reported cooking methods were toasting for breakfast (52%), microwave use for lunch (44%), and baking for dinner (53%) (Figure S2). Sautéing or pan-frying was the second most frequent method for all three meals. Similar to the trend reported by Sun et al. [47], from breakfast to dinner, the frequencies of toaster use declined while baking and boiling increased dramatically.

The results were based on 4500 survey responses. The frequency categories are more than five days a week (red), three to four days a week (yellow), one to two days a week (green), and not used (blue).

More than half of the respondents (58%) indicated that they prefer using the cooktop front burners, 31% used both burners equally, and 11% used the back burners more often. About half of the respondents reported differences in cooktop or oven use by season, with 43% indicating that they used these appliances more frequently during winter than other seasons.

Most respondents had a range hood (59% under-cabinet, 7% wall-mounted, 3% ceiling-mounted) or OTR microwave (19%), with two-thirds reporting that the device was vented to the outdoors (66% of range hoods and 67% of OTR microwaves). Two percent of respondents had downdrafts, with 80% of those being vented to the outside. Ten percent reported having no device above or at the cooktop, and 0.5% reported having other types of devices (e.g., wall exhaust). For homes with a gas or propane stove (14% of total), 74% had a vented range hood, and for homes with an electric stove (86% of total), 64% had a vented range hood.

Home size, construction year, and renter vs. owner occupancy each had a large influence on the likelihood of device presence. Large fractions of respondents who reported not having any device lived in homes smaller than 186 m2 (86%), rental units (57%), or buildings built before 1960 (52%). None of the identified building or household factors was strongly associated with whether devices vented to the outside or only recirculated the air. Some of the analyses presented below consider the venting and recirculating devices together and some explore venting as a potential explanatory factor.

Only 23% of range hoods and 11% of OTR microwaves fully covered the cooktop front burners. Most range hoods (69%) and OTR microwaves (76%) covered only part of the cooktop front burners and about 10% had front burners that were mostly not covered by the hood.

Performance was perceived to be better for venting over recirculating devices in all aspects, including removal of smoke (Cramer’s V = 0.25), odor (Cramer’s V = 0.25), moisture (Cramer’s V = 0.22), and heat (Cramer’s V = 0.22), as well as grease capture (Cramer’s V = 0.16) (Fig. 2). Given the fundamental differences in how the two types of devices operate, the moderate differences in perceived effectiveness are noteworthy. Irrespective of venting, perceived effectiveness was not strongly different among range hoods, OTR microwaves, and downdrafts, suggesting device ventilation mode had a stronger impact on perceived performance than device type.

Results presented for 2439 respondents with a venting device and 1056 with a recirculating device. The ventilation challenges are categorized by the level of removal achieved: all is removed (blue), most is removed (green), some is removed (yellow), and none is removed (red).

Only 10% of respondents who had a venting device and 7% of respondents who had a recirculating device were fully satisfied with their device. Respondents highlighted the following aspects to be improved: less noisy (60% of venting and 64% of recirculating devices), better odor removal (42% of venting and 49% of recirculating devices), better grease removal (41% of venting and 47% of recirculating devices), better smoke removal (38% of venting and 50% of recirculating devices), easier to clean grease screens (35% of venting and 33% of recirculating devices), more coverage for front burners (27% of venting and 25% of recirculating devices), and better heat removal (20% of venting and 32% of recirculating devices).

Among the reasons noted for using a device, removing smoke (79%) and odors (60%) were the most common. Other reasons included removing moisture (38%), capturing grease (27%), removing heat (23%), removing air pollutants emitted by cooking (23%), general kitchen ventilation (23%), and others (1%).

The reported frequency of device use was associated with a number of factors, including cooking method (Cramer’s V = 0.28), ventilation type (Cramer’s V = 0.23), perceived effectiveness (Cramer’s V = 0.20), single speed noise level (Cramer’s V = 0.18), number of speed settings (Cramer’s V = 0.15), and hood coverage for front burners (Cramer’s V = 0.15). Importantly, these findings suggest that venting range hoods are more likely to be used on a regular basis than recirculating range hoods, with 64% of respondents who owned venting range hoods reported using them frequently (“often” or “most of the time”), compared to just 44% of those with recirculating hoods. Figure 3 shows how often the device is used during cooking in general and by influential factors. Respondents who reported not knowing how the ventilation device was used were excluded. The total number and standard error of responses by influential factors are presented in Table S1.

Results presented for 3817 survey responses who reported having a venting or recirculating device above or at the cooktop. Device use is categorized into four frequency categories: always or most of the time (blue), often (green), sometimes (yellow), and rarely or never (red).

For respondents who had range hoods, OTR microwaves, or downdrafts, including both venting and recirculating devices, about 30% reported using them always or most of the time, 57% reported often or sometimes, and 13% reported rarely or never. Respondents reported using their devices most frequently for deep-frying; then stir-frying, sautéing or pan-frying (at similar levels); followed by indoor grilling, boiling, or steaming. Reported device use occurred least often when using a microwave, toaster oven, or toaster. Notably, 47% and 46% reported rarely or never using a device during oven baking and self-cleaning, respectively. Use of a device all or most of the time was much higher for devices that were venting vs. recirculating (36% vs. 18%), had more speed settings (41% for more than two, 18% for one setting), had a quiet fan if only one speed was available (44% for very quiet, 14% for very loud), provided more cooktop coverage (42% for full, 20% for mostly not), or was thought to remove cooking emissions effectively (40% for high, 19% for low). There was no significant difference in ventilation use between homes with electric versus gas stoves (P = 0.17).

The timing of usage relative to the start and end of cooking is important for venting devices. Households benefit most when using it during the entire cooking process. Of the respondents who had a venting device, only 6% indicated that they turned it on when turning on any cooktop burners and turned it off when turning off the last burner (Fig. S3). About 62% of respondents reported using the kitchen venting device only when cooking something that may produce smoke or odors, and 35% reported using it when sensing strong smoke or odors during cooking. Most of the respondents (78%) turned it off when they no longer need to remove smoke, odors, or heat, rather than continuing use until turning off all cooktop burners. Whether having a device or not, 64% of respondents indicated that, when possible, they open kitchen windows during cooking.

All range hoods need to have a mechanism to remove grease particles from the air pulled through the device. This is necessary to prevent combustible organic materials from reaching the motor assembly and duct system, and to reduce grease emissions into the kitchen. The most common form of grease collection is a metal screen; however, some devices use baffles or traps. The cleaning frequency for these devices depends on the design of the grease collection mechanism, the frequency of cooking with oils, and the amount of device use. Grease collected on a screen captures dust, lint, and other large particles creating a need to clean them as often as every 1–2 months with heavy use. A survey question asked, “If your ventilation device has metal grease screens, how often are they cleaned?” While 90% of respondents responded to this question, it is unclear how many of them had baffles or grease traps, and understood the question to refer to any grease capture equipment. With that caveat, it was reported that 17% of grease screens were cleaned every 1–2 months, 27% every 3–6 months, 36% at intervals longer than six months, and 11% were never cleaned. Although there was a strong association between the frequency of grease screen cleaning and range hood usage (Cramer’s V = 0.18), for those who cooked often (cooktop used at least five days a week) and reported using their range hood most of the time during cooking, only 29% and 33% reported cleaning the screens every 1–2 months and 3–6 months, respectively.

One-fourth of the survey respondents had a recirculating device. For this subgroup, 20% (5% of the overall sample) had a charcoal filter and 39% did not know whether their device had a charcoal filter. Twenty-two percent of charcoal filters changed color to indicate when replacement is needed; however, this feature did not lead to more frequent filter replacements in the past six months compared to filters that did not change color (P = 0.49). Figure S4 shows the percentage distribution of responses regarding filter replacement frequencies and reasons.

Respondents who reported having a venting or recirculating device were asked about their knowledge of cooking pollutant hazards, willingness to try specific mitigation strategies (use the device more often, use cooktop back burners while using the device, and use higher speeds when needed) to reduce exposures, and reasons for not being compelled to follow the recommendations. Table 2 shows the willingness to adopt these strategies.

About half of the respondents (52%) did not know that cooking generates unhealthy air pollutants and 39% did not know that cooking on back burners increases the efficiency of a range hood or OTR microwave because they are fully covered by the hood.

There were strong associations among the willingness to adopt the three recommendations (Cramer’s V = 0.28). Sixty-four percent of respondents indicated that they will consider adopting at least one recommendation, and 22% indicated that they will consider adopting all three recommendations. Twenty-four percent of respondents reported having already followed one of the three recommendations, and no respondents reported having followed all three recommendations already. The willingness to adopt the strategies was not statistically significantly different among respondents who reported having a venting or recirculating device.

Noise was the main reason for not using the ventilation device more often or not using a higher speed when needed. Low efficiency was the reason next to noise for not using the device more often. For respondents who reported not having a ventilation device, rental restrictions and no space in the kitchen were the most reported reasons for not installing one. There may have been other factors that prevented the installation of a ventilation device, such as an inability to vent to the outside, that were not surveyed.