S H E L L Y L . M I L L E R , M E C H A N I C A L E N G I N E E R I N GU N I V E R S I T Y O F C O L O R A D O B O U L D E R

EVERYONE NEEDS EXHAUST VENTILATION IN THEIR KITCHENS

2

• 1. Describe the primary emissions of concern from unvented combustion devices, i.e., carbon monoxide, nitrogen dioxide and water vapor.

• 2. Provide an overview of the results from the relevant research conducted on the emissions from unvented combustion appliances.

• 3. Distinguish the various levels of the primary emissions of concern adopted by various national and world health organizations and understand what the health risks are.

• 4. Explain the ventilation effectiveness of various types of exhaust hoods used with unvented cooking appliances.

• 5. Describe the safety devices and the level of allowable emissions from the product safety standards for unvented space heating appliances.

• 6. Describe the national model building code requirements and the importance of providing adequate combustion, ventilation and make up air for the proper operation of unvented combustion appliances.

ASHRAE is a Registered Provider with The American Institute of Architects Continuing Education Systems. Credit earned on completion of this program will be reported to ASHRAE Records for AIA members. Certificates of Completion for non-

AIA members are available on request.

This program is registered with the AIA/ASHRAE for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of

construction or any method or manner of handling, using, distributing, or dealing in any material or product. Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation.

Overall session

Learning objectives

THE PROBLEM WITH NOT HAVING KITCHEN EXHAUST VENTILATION

• Natural gas cooking appliances are used by a third of the the US households (Klug et al 2011)

• Cooking in our homes produces odors, moisture, and pollutants indoors

• Emissions include CO, NO2, H2O, VOCs (HCHO, acrolein), particulate matter, and come from cooking food and/or fuel combustion (Singer et al. 2010; Hu et al. 2012)

• Many of these pollutants cause adverse health effects and are regulated in outdoor air

• Why is it OK to purposely release moisture/odor/pollutants into a small(ish) volume, for which dilution ventilation is relatively low (most homes have low AERs) so that they can stick around for a long time and elevate exposures?

KITCHEN VENTILATION SHOULD BE HIGH PERFORMANCE

(NOT OPTIONAL)(Quote from Brett Singer, LBNL)

Kitchen exhaust ventilation is a great solution – cheap (mostly), low-energy, easy to install (mostly), especially if designed right into the building pre-construction

Exhaust ventilation should be installed for other unvented appliances in homes too

ASHRAE 62.2 REQUIRES KITCHEN EXHAUST VENTILATION

A local mechanical exhaust system shall be installed in each kitchen and bathroom, and shall be either one of the following two:

1. A demand-controlled mechanical exhaust system to be operated as needed by the occupant and have an airflow of 100 cfm or at least 5 kitchen air changes per hour

2. A continuous mechanical exhaust system at 5 kitchen air changes per hour that operates without occupant intervention during all occupiable hours

Range hoods better than general kitchen 200 cfm range hood or kitchen exhaust (simulations)

CO concentration throughout the home: OPEN FLOOR PLAN

High Mixing

No Exhst

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pm)

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Kitchen Exhaust

Hood

15,000 btu/h 800 ng/J COCourtesy of Brett Singer

IT IS VERY GOOD THAT ASHRAE 62.2. REQUIRES KITCHEN EXHAUST

• Unfortunately only a few states require ASHRAE 62.2 to be followed in home construction

• “The only builders who are paying attention to ASHRAE 62.2 at this point (outside of CA, where ASHRAE 62.2 is referenced in the Title 24 energy code) are builders of tight, energy-efficient homes.” (http://www.greenbuildingadvisor.com/blogs/dept/musings/how-much-fresh-air-does-your-home-need , Martin Holladay)

P.S. IS KITCHEN VENTILATION NEEDED FOR ELECTRIC COOKING?

üRemove smoke as neededüRemove odors & moistureüRemove pollutants from burners and

cooking

So…yes

LITERATURE ON THIS TOPIC IS EXTENSIVE

A FEW REPRESENTAT IVE PAPERS INCLUDED HERE

AIR POLLUTANTS FROM BURNERS AND COOKING

• Levy 1998: Personal NO2 exposure strongly correlated with indoor concentrations, use of gas stove was dominant activity influencing NO2concentrations (n=586 18 cities 15 countries)

• Dennekamp et al. 2001: high concentrations of particles less than 100 nm generated by gas combustion, frying, cooking fatty foods, cooking with electric stoves, NOx generated using gas stove (peaks of 1000 ppb NO2)

• Evans et al. 2004: ultrafine and PM2.5 particles are generated by frying and inhalation dose estimated to be significant to home occupants when compared to outside sources

• He et al. 2004: frying, grilling, stove use, toasting, cooking pizza, cooking could elevate ultrafine particles by > 5x, PM2.5 increased 30-90 times higher during frying and grilling

• Seaman et al. 2007, 2009: lung irritant acrolein shown to be elevated during cooking, and produced by heated cooking oils

• Singer et al. 2010: measured emission rates from cooktop burners in ng/J: 0.09-4.7 HCHO; 5-17.7 NO2; 7-823 CO; 11-1380 104/J particle number. Depended on burner design, fuel blend.

POLLUTANT STANDARD AND GUIDELINE CONCENTRATIONS

Pollutant 1-h average 8-h average 24-h average Standard

NO2 100 ppb(188 µg/m3)

NA NA NAAQS (EPA 2012b)

CO 20 ppm (23 mg/m3)

9 ppm (10 mg/m3)

NA CAAQS (CARB 2010)

PM2.5 NA NA 35 µg/m3 NAAQS (EPA 2012b)

HCHO 35 ppb (55 µg/m3)

7.3 ppb (9 µg/m3)

Non-cancerREL (OEHHA 2007)

RECENT MODELING STUDY OF POLLUTANT EXPOSURE FROM NATURAL GAS COOKING

• Used sample cohort representing So CA households• More than 50% use natural gas to cook• Used data on the homes, occupants, cooking behavior, air

exchange rate estimates, occupancy, outdoor air concentrations in simulation model

• Gas burners added 25-39% to the week-averaged indoor NO2 concentrations, and 21-30% to the indoor CO

• When homes did not use exhaust ventilation, household exposures frequently exceeded federal and state health-based standards for CO, NO2• 1.7 million Californians could be exposed to CO levels that

exceed NAAQS for outdoor air and 12 million exposed to excessive NO2 levels if they don’t use the exhaust ventilation(Logue et al. 2014)

THE POLLUTANT THING IS A SERIOUS ISSUE!

• Among homes that cook with gas & don’t use range hood*:

• 55-70% exceed NO2 1-h standards• 27% exceed formaldehyde 1-h guidelines• 8% exceed CO 1-h and 8-h standards

*Logue et al. 2014

Pollutant exposures from gas cooking burners

Environmental Health Perspectives t VOLUME 122 | NUMBER 1 | January 2014 45

characteristics and weekly patterns of meals cooked. This survey provided meal-specific data on the frequency of oven use, number of cooktop burners used, and duration of burner use. Based on the cooking survey, the model assumes one cooktop burner for breakfast or lunch and two cooktop burners for dinner and also includes oven use for all dinners cooked in half of the homes. The duration of each discrete cooking event was assigned by sampling from lognormal distributions of cooktop and oven use duration for the spe-cific meal (breakfast, lunch, dinner), based on data collected in the cooking survey (Klug et al. 2011b); the distribution summary statis-tics are provided in Supplemental Material, Table S1. We used the median reported data from the National Human Activity Patterns Survey (NHAPS) (Klepeis et al. 2001) to establish meal times and to establish arche-typal home occupancy patterns based on occupant age (0–5, 6–17, 18–64, ≥ 65 years) and weekend or weekday (for specific assign-ments, see Supplemental Material, Table S2). Cooking burner emission factors for NO2, CO, and HCHO were based on measure-ments reported by Singer et al. (2010) for twelve ranges, each including a cooktop and oven. Each home was randomly assigned the emission factors from one cooktop and one oven from the data set and those emission fac-tors were used for all modeling of the home.

AER. Distributions of empirical AERs were developed from studies reporting AER measurements in Southern California homes (Health Effects Institute 2010; Offerman 2009; Wilson et al. 1993, 2003). Distributions were developed for winter and non-winter seasons for three home age ranges by date of construction (pre-1980, 1981–1995, and post-1995). We randomly sampled from these distributions to select a winter AER and a summer AER for each home based on home age. Summer AERs were higher, likely due to more window opening. Higher summer AERs result in lower modeled concentration estimates in summer compared with winter. Relative to the 2003 RASS database, the current (ca. 2013) California housing stock includes newer homes with lower AERs. Lower AERs translate to less dilution and higher concen-trations of pollutants from indoor sources.

Outdoor air pollutants. Typical outdoor NO2 and CO profiles were developed for each county for a winter week and a sum-mer week based on concentrations mea-sured at ambient air quality monitoring sites. Data were downloaded from the U.S. Environmental Protection Agency (EPA) AirData website (U.S. EPA 2012a). A rep-resentative monitoring site was selected for each county and all homes in that county were assumed to have the same outdoor

concentrations. If more than one monitor-ing site existed in a county, we selected the site that reported the median annual average concentration from among the available sites reporting data from the county. Hourly out-door profiles for each site were developed by calculating the average concentrations from all available data from 2008–2009 by hour and by day of the week. Whereas indoor con-centrations of NO2 and CO can be domi-nated by contributions from outdoor air and unvented indoor combustion sources, indoor HCHO concentrations typically depend on a wider variety of sources, including mate-rial emissions, chemical reactions, outdoor sources, and indoor combustion (Salthammer et al. 2010; Zhang et al. 1994). We did not incorporate HCHO from other indoor or outdoor sources into the analysis; therefore, our estimates of indoor HCHO concentra-tions reflect only the incremental contribu-tion of NGCB exhaust.

Estimated pollutant concentrations were linked to archetypal patterns of home occu-pancy according to age group (0–5, 6–18, 19–64, ≥ 65 years) for each individual resid-ing in each modeled home (Klepeis et al. 2001); this was done to explore the impact of

age-based activity patterns on individual-level exposures. When occupants were not home based on occupancy profiles, their exposure concentrations were assumed to be zero.

Proximity factors. The model accounts for elevated concentrations of NGCB pollut-ants in the kitchen relative to other parts of the home (Berwick et al. 1989; Hoek et al. 1984; Noy and Lebret 1986; Palmes et al. 1977, 1979) and assumes that anyone in the kitchen during cooking will be exposed to these higher concentrations. We account for this proximity effect by assigning one adult cook for each cooking event and by assum-ing that any young children (0–5 years of age) present in the home during cook-ing are nearby. Exposures are calculated by multiplying the estimated indoor-generated pollutant concentration by proximity fac-tors (Fprox) of 2.0 for the cook and 1.5 for children 0–5 years of age, then adding the contribution from outdoor sources, which was assumed to be uniform throughout the home. Proximity factors were determined by reviewing published data on burner-related pollutant concentration in kitchens and other areas of the home and determining ratios of concentrations measured in kitchens

Figure  1. Example results: simulated time-resolved NO2 concentrations in a 36-year-old, 1,125-ft2 home with four occupants (one 0–5, one 6–18, and two 35–54 years of age) for 1 week in winter. (A) Indoor concentration of NO2 originating from indoor and outdoor sources. (B) Simulated exposure concentration experienced by the two occupants assumed to not be near the cooking activity (Fprox = 1). (C) Simulated exposure concentration for the cook (Fprox =  2) and a small child assumed to be near the cooking (Fprox = 1.5).

From infiltration From indoor sources Total concentration

Child (6–18 years) not with cook 1-week exposure = 10.6 µg/m3

Adult (non-cook)1-week exposure = 9.9 µg/m3

Adult cook1-week exposure = 11.6 µg/m3

Child (0–5 years) with cook1-week exposure = 10.6 µg/m3

200

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SIMULATED NO2 LEVELS IN A HOME

SLOAN IAQ STUDY CU BOULDER

Pump box

Pumps

PM2.5 Impactor

Microbial filter

IAQ Calc:CO,CO2, Temp, RH

Mufflers

PM10 – instant

15

PM10 - COOKING WITH EXHAUST

PM10 - COOKING NO EXHAUST

GAS COOKING BURNERS REQUIRE VENTING: EVIDENCE OF ELEVATED CO EXPOSURES

Data from California IAQ Study 2011-2013. 2011-12 data described in Mullen et al. 2013

GAS COOKING BURNERS REQUIRE VENTING: EVIDENCE OF ELEVATED NO2 EXPOSURES

Data from California IAQ Study 2011-2013. 2011-12 data described in Mullen et al. 2013

NO2 CONCENTRATIONS IN RESIDENCES LEE ET AL. 1998

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ElectricGas

N=50N=49

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N=248N=271

N=276

A COUPLE OF EPIDEMIOLOGIC STUDIES OF POLLUTANTS ASSOCIATED WITH COOKING

• Belanger et al. 2013: Every 5-fold increase in NO2 exposure above 6 ppb was associated* with a dose-dependent increase in risk of higher asthma severity, wheeze, rescue medication use (n=1,342)

• Schwartz and Neas 2000: lower respiratory tract symptoms (cough, phlegm, chest pain, wheezing) *associated with 15 µg/m3 increase in PM2.5 (n=1,844 Harvard Six City Diary Study)

• Bell et al. 2009: a 1-ppm increase in same-day 1-h maximum CO was associated with 1% increase in risk of cardiovascular disease hospitalization (n=126 counties)

• Touloumi et al. 1997: significant positive association found between daily deaths and NO2. increases of 50 µg/m3 of NO2were associated with a 1.3% increase in the daily number of deaths (6 European cities, 19 million population)

* Indicates statistically significant at the 95% confidence level

CO FROM UNVENTED FIREPLACE

Dutton et al 2001CU Boulder unvented Fireplace emissions study

Not much published data on other unvented appliances

SOME PARTING THOUGHTS….

• Many US homes currently don’t have venting range hoods• Must be retrofitted, need incentives, education about health effects to

commit to install• Many of the installed hoods are ineffective• Need to design better hoods with higher capture efficiencies

• A minority of households use kitchen ventilation routinely• 25-40% of survey volunteers in CA (likely high)• noisy

• Do we need to require automatic operation?• Are we satisfied with leaving it to the user? • Will quieter products and education lead to more frequent use?

• Let’s work to get more vents in kitchens • …and lets not add additional unvented appliances indoors!• Will emit similar pollutants into the home

REFERENCES

• Belanger et al. (2013) Household levels of nitrogen dioxide and pediatric asthma severity. Epidemiology 24(2):320-330• Bell et al. (2009) Emergency hospital admissions for cardiovascular diseases and ambient levels of carbon monoxide: Results

for 126 U.S. Urban counties, 1999-2005. Circulation 120(11):949-955• Dennekamp et al. (2001) Ultrafine particles and nitrogen oxides generated by gas and electric cooking. Occup Environ Med

58:511-516• Dutton et al. (2001) Indoor pollutant levels from the use of unvented natural gas fireplaces in Boulder, Colorado. JAWMA

51:1654-1661• He et al. (2004) Contribution from indoor sources to particle number and mass concentrations in residential houses. Atmos

Environ 38(21):3405-3415• Hu et al. (2012) Compilation of Published PM2.5 Emission Rates for Cooking, Candles and Incense for Use in Modeling of

Exposures in Residences. LBNL-5890E. Berkeley, CA: Lawrence Berkeley National Laboratory. • Klug VL, et al. (2011) Cooking Appliance Use in California Homes—Data Collected from a Web-based Survey. LBNL-5028E.

Berkeley, CA: Lawrence Berkeley National Laboratory. Available:http://homes.lbl.gov/sites/all/files/lbn l-5028e-cooking-appliance.pdf

• Lee et al. (1998) The Boston residential nitrogen dioxide characterization study: classification and prediction of indoor NO2exposure. JAWMA 48:736-742

• Levy (1998) Impact of residential nitrogen dioxide exposure on personal exposure: an international study. JAWMA 48(6):553-560

• Logue JM, et al. (2014) Pollutant exposures from natural gas cooking burners: a simulation-based assessment for Southern California. Environ Health Perspect 122(1):43–50; http://dx.doi.org/10.1289/ehp.1306673.

• Schwartz and Neas (2000) Fine particles are more strongly associated than coarse particles with acute respiratory health effects in school children. Epidemiology 11(1):6-10

• Seaman et al. (2009) Indoor acrolein emission and decay rates resulting from domestic cooking events. Atmos Environ 43(39):6199-6204

• Seaman et al. (2007) Origin, occurrence, and source emission rate of acrolein in residential indoor air. ES&T 41(20):6940-6946• Singer et al. (2010) Experimental evaluation of pollutant emissions from residential appliances. LBNL paper LBNL-2897E,

http://escholarship.org/uc/item/94c554f4• Touloumi et al. (1997) Short-term effects of ambient oxidant exposure on mortality: a combined anaysis within the APHEA

project. Amer J. Epidemiol. 146:177-85. http://aje.oxfordjournals.org/content/146/2/177.short

SHELLY L. MILLERUNIVERSITY OF COLORADO BOULDER

SHELLY .MILLER@COLORADO.EDU