Increasing co-occurrence of fine particulate matter and ground-level ozone extremes in the western United States

Kalashnikov, Dmitri A.; Schnell, Jordan L.; Abatzoglou, John T.; Swain, Daniel L.; Singh, Deepti

doi:10.1126/sciadv.abi9386

Cited by 51 publications

(33 citation statements)

References 75 publications

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“…Effect estimates for respiratory mortality were somewhat larger than cardiovascular and all-cause mortality. The larger association with respiratory mortality was plausible because the extreme PM 2.5 days in the Western United States were mostly driven by wildfires ( 6 ). In studies of wildfires and associated PM 2.5 and hospital admissions, associations with respiratory illnesses were stronger than with cardiovascular admissions ( 46 ).…”

Section: Discussionmentioning

confidence: 99%

The Effects of Coexposure to Extremes of Heat and Particulate Air Pollution on Mortality in California: Implications for Climate Change

Rahman¹,

McConnell²,

Schlaerth

et al. 2022

Am J Respir Crit Care Med

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Rationale Extremes of heat and particulate air pollution threaten human health and are becoming more frequent because of climate change. Understanding the health impacts of coexposure to extreme heat and air pollution is urgent. Objectives To estimate the association of acute coexposure to extreme heat and ambient fine particulate matter (PM 2.5 ) with all-cause, cardiovascular, and respiratory mortality in California from 2014 to 2019. Methods We used a case-crossover study design with time-stratified matching using conditional logistic regression to estimate mortality associations with acute coexposures to extreme heat and PM 2.5 . For each case day (date of death) and its control days, daily average PM 2.5 and maximum and minimum temperatures were assigned (0- to 3-day lag) on the basis of the decedent’s residence census tract. Measurements and Main Results All-cause mortality risk increased 6.1% (95% confidence interval [CI], 4.1–8.1) on extreme maximum temperature-only days and 5.0% (95% CI, 3.0–8.0) on extreme PM 2.5 -only days, compared with nonextreme days. Risk increased by 21.0% (95% CI, 6.6–37.3) on days with exposure to both extreme maximum temperature and PM 2.5 . Increased risk of cardiovascular and respiratory mortality on extreme coexposure days was 29.9% (95% CI, 3.3–63.3) and 38.0% (95% CI, −12.5 to 117.7), respectively, and were more than the sum of individual effects of extreme temperature and PM 2.5 only. A similar pattern was observed for coexposure to extreme PM 2.5 and minimum temperature. Effect estimates were larger over age 75 years. Conclusions Short-term exposure to extreme heat and air pollution alone were individually associated with increased risk of mortality, but their coexposure had larger effects beyond the sum of their individual effects.

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Section: Discussionmentioning

confidence: 99%

The Effects of Coexposure to Extremes of Heat and Particulate Air Pollution on Mortality in California: Implications for Climate Change

Rahman¹,

McConnell²,

Schlaerth

et al. 2022

Am J Respir Crit Care Med

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“…This would require an expanded time series of smoke PM 2.5 concentrations that is not currently available from the HRRR-Smoke model that became operational in 2020; therefore, other observational or modeling datasets are needed to backfill historical smoke patterns. Third, future climate change scenarios may alter HSC frequency and duration (Kalashnikov et al 2022), but future projection was beyond the scope of this analysis. Finally, we can further investigate the social drivers of differential exposure between racial and ethnic groups including housing stock, urban tree canopy cover and occupation.…”

Section: Discussionmentioning

confidence: 99%

“…Austin et al (2020) examined exposure to HSC among outdoor agricultural workers at the county level in Washington and found strong spatiotemporal variability in areas exposed to high heat and high levels of PM 2.5 , and that these exposures occured prima during the summer wildfire season (Austin et al 2020). More recently, researchers examined the co-occurrence of heat, ozone and PM 2.5 in the Western United States (Kalashnikov et al 2022). These two studies, however, used concentration measurements that include all sources of PM 2.5 (versus smoke-specific PM 2.5 ) and relied on either unevenly distributed air quality stations or a coarse 10 km resolution, respectively.…”

Section: Introductionmentioning

confidence: 99%

Population co-exposure to extreme heat and wildfire smoke pollution in California during 2020

Rosenthal

Benmarhnia

Ahmadov

et al. 2022

Environ. Res.: Climate

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Excessive warming from climate change has increased the total wildfire burned area over the past several decades in California. This has increased population exposure to both hazardous concentrations of air pollutants from fires such as fine particulate matter (smoke PM2.5) and extreme heat events. Exposure to PM2.5 and extreme heat are individually associated with negative health impacts and recent epidemiological evidence points to synergistic effects from concurrent exposures. This study characterizes the frequency and spatial distribution of co-occurring extreme heat and smoke PM2.5 events in California during the record-setting wildfire season of 2020. We measure exceedances over extreme thresholds of modeled surface-level smoke PM2.5 concentrations and heat index based on observed temperature and humidity. We estimate that, during the studied period, extreme smoke and heat co-occurred at least once within 68% of the State’s area (~288,000 km2) and an average 2.5 times across all affected areas. Additionally, 16.5 million people, mostly in lower population density areas, were impacted at least once in 2020 by such synergistic events. Our findings suggest that public health guidance and adaptation policies should account for co-exposures, not only distinct exposures, when confronting heat and smoke PM2.5.

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“…In the U.S., smoke has become an increasingly challenging problem due to a significant increase in the area burned by wildfires (Zhuang et al 2021;Kalashnikov et al 2022;McClure and Jaffe 2018). Data from the National Interagency Fire Center (www.nifc.gov) show that between the early 1980s and 2021, the decadal average annual area burned by wildfires in the U.S. has increased by almost a factor of 3, from 1.1 to 3.0 million ha per year.…”

Section: Introductionmentioning

confidence: 99%

Technical note: Use of PM<sub>2.5</sub> to CO ratio as a tracer of wildfire smoke in urban areas

Jaffe

Schnieder²,

Inouye³

2022

Preprint

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Abstract. Wildfires, and the resulting smoke, are an increasing problem in many regions of the world. However, identifying the contribution of smoke to pollutant loadings in urban regions can be challenging at lower concentrations due to the presence of the usual array of anthropogenic pollutants. Here we propose a method using the difference in PM to CO emission ratios between smoke and typical urban pollution. For smoke, emission ratios of PM2.5 to CO are between 200–300 µg m−3 ppb−1, whereas typical urban sources have an emission ratio that is lower by a factor of 4–10. This gives rise to the possibility of using this ratio as an indicator of smoke extent. We use observations a regulatory surface monitoring sites in Sparks, NV, for the period of May–September 2018–2021. During this time, there were many smoke-influenced periods from numerous California wildfires that burned during this period. Using a PM / CO ratio of 30, we can split the data into smoke-influenced and no-smoke periods. We then develop a Monte Carlo simulation, tuned to local conditions, to derive a set of PM2.5 / CO values that can be used to identify smoke influence in urban areas. From the simulation, we find that a smoke enhancement ratio of 140 µg m−3 ppb−1 best fits the observations, which is significantly lower than the ratio observed in fresh smoke plumes. The most likely explanation for this difference is greater loss of PM2.5 during dilution and transport to warmer surface layers. We find that the PM2.5 / CO ratio in urban areas is an excellent indicator of smoke and should prove to be useful to identify biomass burning influence on the policy relevant concentrations of both PM2.5 and O3. Using the results of our Monte Carlo simulation, this ratio can also quantify the influence of smoke on urban PM2.5.

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Increasing co-occurrence of fine particulate matter and ground-level ozone extremes in the western United States

Abstract: More frequent atmospheric ridging and wildfires increase exposure of western U.S. population to co-occurring air pollutants.

Cited by 51 publications

References 75 publications

The Effects of Coexposure to Extremes of Heat and Particulate Air Pollution on Mortality in California: Implications for Climate Change

The Effects of Coexposure to Extremes of Heat and Particulate Air Pollution on Mortality in California: Implications for Climate Change

Population co-exposure to extreme heat and wildfire smoke pollution in California during 2020

Technical note: Use of PM<sub>2.5</sub> to CO ratio as a tracer of wildfire smoke in urban areas

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Increasing co-occurrence of fine particulate matter and ground-level ozone extremes in the western United States

Abstract: More frequent atmospheric ridging and wildfires increase exposure of western U.S. population to co-occurring air pollutants.

Cited by 51 publications

References 75 publications

The Effects of Coexposure to Extremes of Heat and Particulate Air Pollution on Mortality in California: Implications for Climate Change

The Effects of Coexposure to Extremes of Heat and Particulate Air Pollution on Mortality in California: Implications for Climate Change

Population co-exposure to extreme heat and wildfire smoke pollution in California during 2020

Technical note: Use of PM&lt;sub&gt;2.5&lt;/sub&gt; to CO ratio as a tracer of wildfire smoke in urban areas

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About

Technical note: Use of PM<sub>2.5</sub> to CO ratio as a tracer of wildfire smoke in urban areas