Characterizing peak exposure of secondhand smoke using a real-time PM2.5 monitor

Sources of personal PM2.5 exposure during pregnancy in the MADRES cohort

BACKGROUND

Personal exposure to fine particulate matter (PM2.5) is impacted by different sources each with different chemical composition. Determining these sources is important for reducing personal exposure and its health risks especially during pregnancy.

OBJECTIVE

Identify main sources and their contributions to the personal PM2.5 exposure in 213 women in the 3rd trimester of pregnancy in Los Angeles, CA.

METHODS

We measured 48-hr integrated personal PM2.5 exposure and analyzed filters for PM2.5 mass, elemental composition, and optical carbon fractions. We used the EPA Positive Matrix Factorization (PMF) model to resolve and quantify the major sources of personal PM2.5 exposure. We then investigated bivariate relationships between sources, time-activity patterns, and environmental exposures in activity spaces and residential neighborhoods to further understand sources.

RESULTS

Mean personal PM2.5 mass concentration was 22.3 (SD = 16.6) μg/m3. Twenty-five species and PM2.5 mass were used in PMF with a final R2 of 0.48. We identified six sources (with major species in profiles and % contribution to PM2.5 mass) as follows: secondhand smoking (SHS) (brown carbon, environmental tobacco smoke; 65.3%), fuel oil (nickel, vanadium; 11.7%), crustal (aluminum, calcium, silicon; 11.5%), fresh sea salt (sodium, chlorine; 4.7%), aged sea salt (sodium, magnesium, sulfur; 4.3%), and traffic (black carbon, zinc; 2.6%). SHS was significantly greater in apartments compared to houses. Crustal source was correlated with more occupants in the household. Aged sea salt increased with temperature and outdoor ozone, while fresh sea salt was highest on days with westerly winds from the Pacific Ocean. Traffic was positively correlated with ambient NO2 and traffic-related NOx at residence. Overall, 76.8% of personal PM2.5 mass came from indoor or personal compared to outdoor sources.

IMPACT

We conducted source apportionment of personal PM2.5 samples in pregnancy in Los Angeles, CA. Among identified sources, secondhand smoking contributed the most to the personal exposure. In addition, traffic, crustal, fuel oil, fresh and aged sea salt sources were also identified as main sources. Traffic sources contained markers of combustion and non-exhaust wear emissions. Crustal source was correlated with more occupants in the household. Aged sea salt source increased with temperature and outdoor ozone and fresh sea salt source was highest on days with westerly winds from the Pacific Ocean.

Exposure to fine particulate matter (PM2.5) from non-tobacco sources in homes within high-income countries: a systematic review

The health impacts associated with exposure to elevated concentrations of fine particulate matter (PM_2.5) are well recognised. There is a substantial number of studies characterising PM_2.5 concentrations outdoors, as well as in homes within low- and middle-income countries. In high-income countries (HICs), there is a sizeable literature on indoor PM_2.5 relating to smoking, but the evidence on exposure to PM_2.5 generated from non-tobacco sources in homes is sparse. This is especially relevant as people living in HICs spend the majority of their time at home, and in the northern hemisphere households often have low air exchange rates for energy efficiency. This review identified 49 studies that described indoor PM_2.5 concentrations generated from a variety of common household sources in real-life home settings in HICs. These included wood/solid fuel burning appliances, cooking, candles, incense, cleaning and humidifiers. The reported concentrations varied widely, both between sources and within groups of the same source. The burning of solid fuels was found to generate the highest indoor PM_2.5 concentrations. On occasion, other sources were also reported to be responsible for high PM_2.5 concentrations; however, this was only in a few select examples. This review also highlights the many inconsistencies in the ways data are collected and reported. The variable methods of measurement and reporting make comparison and interpretation of data difficult. There is a need for standardisation of methods and agreed contextual data to make household PM_2.5 data more useful in epidemiological studies and aid comparison of the impact of different interventions and policies.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11869-022-01288-8.

Impact of Airline Secondhand Tobacco Smoke Exposure on Respiratory Health and Lung Function Decades After Exposure Cessation

BACKGROUND

Twenty-five percent to 45% of COPD is caused by exposures other than active smoking. Secondhand tobacco smoke (SHS) has been suggested as an independent cause of COPD, based on its association with increased respiratory symptoms and a small decrease in lung function, but its impact on respiratory health and lung function after exposure cessation has not been explored.

RESEARCH QUESTION

What are the consequences of airline SHS exposure on respiratory health and lung function decades after cessation?

STUDY DESIGN AND METHODS

We performed a cohort study involving flight attendants because of their exposure to SHS that stopped > 20 years ago. We included subjects ≥ 50 years of age with > 1 year vs ≤ 1 year of airline SHS exposure (ie, exposed vs unexposed). Respiratory quality of life, as determined by the St. George's Respiratory Questionnaire (SGRQ), was the primary outcome for respiratory health. Key secondary outcomes included general quality of life (the Rand Corporation modification of the 36-item Short Form Health Survey Questionnaire; RAND-36), respiratory symptoms (COPD Assessment Test; CAT), and spirometry.

RESULTS

The study enrolled 183 SHS-exposed and 59 unexposed subjects. Exposed subjects were 66.7 years of age, and 90.7% were female. They were hired at 23.8 years of age, were exposed to airline SHS for 16.1 years, and stopped exposure 27.5 years before enrollment. Prior SHS exposure was associated with worsened SGRQ (6.7 units; 95% CI, 2.7-10.7; P = .001), RAND-36 physical and social function, and CAT vs unexposed subjects. SHS exposure did not affect prebronchodilator spirometry or obstruction, but was associated with lower postbronchodilator FEV1 and FEV1/FVC, total lung capacity, and diffusing capacity of the lungs for carbon monoxide in a subset of subjects. Former smoking and SHS exposure synergistically worsened SGRQ (β = 8.4; 95% CI, 0.4-16.4; P = .04). SHS exposure in people who never smoked replicated primary results and was associated with worsened SGRQ vs unexposed people (4.7 units; 95% CI, 0.7-7.0; P = .006).

INTERPRETATION

Almost three decades after exposure ended, airline SHS exposure is strongly and dose-dependently associated with worsened respiratory health, but less robustly associated with airflow abnormalities used to diagnose COPD.