Pollutant exposures from natural gas cooking burners: a simulation-based assessment for Southern California

Abstract

Background: Residential natural gas cooking burners (NGCBs) can emit substantial quantities of pollutants, and they are typically used without venting range hoods.

Objective: We quantified pollutant concentrations and occupant exposures resulting from NGCB use in California homes.

Methods: A mass-balance model was applied to estimate time-dependent pollutant concentrations throughout homes in Southern California and the exposure concentrations experienced by individual occupants. We estimated nitrogen dioxide (NO2), carbon monoxide (CO), and formaldehyde (HCHO) concentrations for 1 week each in summer and winter for a representative sample of Southern California homes. The model simulated pollutant emissions from NGCBs as well as NO2 and CO entry from outdoors, dilution throughout the home, and removal by ventilation and deposition. Residence characteristics and outdoor concentrations of NO2 and CO were obtained from available databases. We inferred ventilation rates, occupancy patterns, and burner use from household characteristics. We also explored proximity to the burner(s) and the benefits of using venting range hoods. Replicate model executions using independently generated sets of stochastic variable values yielded estimated pollutant concentration distributions with geometric means varying by <10%.

Results: The simulation model estimated that-in homes using NGCBs without coincident use of venting range hoods-62%, 9%, and 53% of occupants are routinely exposed to NO2, CO, and HCHO levels that exceed acute health-based standards and guidelines. NGCB use increased the sample median of the highest simulated 1-hr indoor concentrations by 100, 3,000, and 20 ppb for NO2, CO, and HCHO, respectively.

Conclusions: Reducing pollutant exposures from NGCBs should be a public health priority. Simulation results suggest that regular use of even moderately effective venting range hoods would dramatically reduce the percentage of homes in which concentrations exceed health-based standards.

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 (F_prox = 1). (C) Simulated exposure concentration for the cook (F_prox = 2) and a small child assumed to be near the cooking (F_prox = 1.5).

Figure 2

One-week time-averaged indoor pollutant concentrations estimated by simulation modeling for weighted sample of 6,634 of SoCal homes. Both summer (scenario 2) and winter (scenario 1) results presented in this figure assume no range hood use and apply near-source proximity factors to estimate exposure concentrations. Boxes indicate 25th (bottom), 50th (line within box), and 75th (top) percentiles; whiskers represent 5th and 95th percentiles. Dashed horizontal lines are standards from Table 1 that are within ranges shown on graphs. Results presented for scenario 1 are the mean values from 15 model executions. See Supplemental Material, Table S3, for tabulated results.

Figure 3

Highest 1-hr time-averaged indoor pollutant concentrations estimated by simulation modeling of the weighted sample of 6,634 SoCal homes and exposure concentrations for the weighted sample of 19,464 individual occupants. Estimated indoor concentrations presented for scenario 1 (winter) and scenario 2 (summer), both of which assume no range hood use. Estimated exposure concentrations presented in this figure all apply near-source proximity factors, with one pair of scenarios assuming no range hood use and the second pair of scenarios assuming use of a range hood with 55% capture efficiency (CE) during every cooking event. Boxes indicate 25th (bottom), 50th (line within box), and 75th (top) percentiles; whiskers represent 5th and 95th percentiles. Dashed horizontal lines are standards from Table 1 that are within ranges shown on graphs. Results presented for scenario 1 are the mean values from 15 model executions. See Supplemental Material, Table S3, for tabulated results.