Effects of Exposure to New Car Interiors in Patients With Asthma and Allergic Rhinitis.

RATIONALE: Vehicle interiors are an important microenvironment for atopic subjects. This study evaluated the subjective and objective physiologic and clinical effects of exposing subjects with asthma and allergic rhinitis to new 2017 Mercedes vehicles during 90-minute rides.
METHODS: Ten adult asthmatics with allergic rhinitis were assessed before and 45 and 90 minutes into rides in a 2017 Mercedes-Benz S-Class sedan and GLE-Class SUV on 2 separate days. Assessments included spirometry, fractional exhaled nitric oxide, peak nasal inspiratory flow, asthma symptom scores, and physical examinations.
RESULTS: Of the 10 subjects, 6 were women, mean age was 32 years, and 6 and 4 were using chronic asthma controllers or intranasal corticosteroids, respectively. None of the subjects had worsening of asthma or rhinitis symptoms during the rides. There were no statistically significant changes from baseline in forced expiratory volume in 1 second, forced expiratory volume in 1 second:forced vital capacity ratio, forced expiratory flow at 25%-75% of vital capacity, fractional exhaled nitric oxide, or peak nasal inspiratory flow at 45 or 90 minutes into the rides with either Mercedes vehicle (all P values > .1 using generalized linear mixed model).
CONCLUSION: The interior environment of the tested Mercedes vehicles did not cause changes in subjective or objective measures of asthma and allergic rhinitis. We suggest that this model system can be used to test other vehicles for putatively adverse effects on patients with allergic respiratory disorders.

Introduction

Vehicle interiors are an important microenvironment for atopic subjects. The quality of air inside motor vehicles may be compromised by interior and exterior factors, such as volatile organic compounds (VOCs), polybrominated diphenylesthers (PBDEs) and other brominated flame retardants, phthalic acid esters (phthalates), aromatic hydrocarbons, particulate matter, odors, and pollutants.[1-3] VOCs, PBDEs, and phthalates may be released from materials used to manufacture vehicle interiors, and VOC concentrations inside vehicles may exceed those normally detected in residential indoor air.[1,2] Pollutants, chemicals, and other irritants, especially VOCs, in vehicle interiors are capable of exacerbating symptoms in atopic individuals.[3-10] In addition, strong odors, often present in new cars, can aggravate asthma, and aeroallergens theoretically may be transferred to vehicle interiors during peak pollen season.[8]

Methods

In this small prospective study, we investigated the physiologic and clinical effects of exposing asthmatics with allergic rhinitis to new vehicle interiors to determine the tolerability to this microenvironment. Testing was performed according to the criteria for allergy friendly car interiors established by the European Centre for Allergy Research Foundation based on an international expert advisory board consensus. This study was funded by Mercedes-Benz USA, LLC and approved by the University of South Florida Institutional Review Board.

Ten adult asthmatic subjects with allergic rhinitis were recruited for and completed the study. After signing informed consent, pertinent medical histories were recorded for each subject at enrollment. Each subject was driven by a professional driver in 2 new 2017 Mercedes-Benz vehicles, the S-Class sedan and GLE-Class SUV, for 90 minutes on separate days. A physician and study coordinator accompanied the subject on the drives. No measures were taken to air out the vehicles; windows remained closed and the air-conditioning turned on with central circulation during the rides. Assessments were collected before (predrive, time 0), 45 minutes into (middrive), and 90 minutes into (postdrive) each ride. The predrive assessment was either completed as an independent visit or immediately preceding the first drive. The middrive assessment was completed while the vehicle was stopped at a secure location. The subject remained inside the vehicle for the entire 90 minutes. Assessments included spirometry; fractional exhaled nitric oxide (FeNO); peak nasal inspiratory flow (PNIF); asthma symptom scores; and physical examinations of the ocular, nasal, oropharyngeal, cardiovascular, and pulmonary systems. Asthma symptom scores consisted of evaluations of wheezing, shortness of breath, cough, and chest tightness on a 7-point scale from 1 (not bothered) to 7 (extremely bothered). For FeNO and PNIF, the mean of and best of 2 successive measurements were used for each time point, respectively.

Subjects’ baseline demographic and clinical variables were assessed by examining means and standard deviation for continuous variables and frequency for dichotomous variables. For variables measured longitudinally, a generalized linear mixed model was used without adjustment. Data analyses were performed using SAS 9.4 (SAS Institute Inc., CA). The level of significance was set at alpha 0.05.

Results

Baseline characteristics are listed in Table 1. Sixty percent (6/10) of participants were women, 80% (8/10) were white, and the mean age was 32 years. Of note, 1 subject had a baseline forced expiratory volume in 1 second < 70% predicted at study initiation and 1 subject had a baseline FeNO > 150 ppb which remained elevated throughout the study. There were no significant differences in any of the parameters measured for the 3 time points during the rides in either vehicle (Table 2). There were also no clinically significant changes in physical examinations.

Table 1.

Baseline Characteristics of Study Participants.

Characteristic	Subjects (N = 10)
Age (IQR)	32 (22–60)
Male sex (%)	4 (40)
Race—no. (%)
White	8 (80)
Black	1 (10)
Other (Guyanese)	1 (10)
Smoking history (%)	1 (10)
Time since asthma diagnosis in years (SD)	16.4 (15.57)
Asthma controller usage (%)	6 (60)
Intranasal corticosteroid usage (%)	4 (40)
FEV1 < 70% predicted at baseline (%)	1 (10)
FeNO > 150 ppb at baseline (%)	1 (10)

Abbreviations: FeNO, fractional exhaled nitric oxide; FEV1, forced expiratory volume in 1 second; IQR, interquartile range; SD, standard deviation; ppb, parts per billion.

Table 2.

Change in Airway Parameters and Symptom Scores at Baseline and 45 and 90 Minutes Into Rides in 2017 Mercedes-Benz S-Class Sedans and GLE-Class SUVs.

	Pre (0 min) (N = 10)	Mid (45 min) (N = 10)	Post (90 min) (N = 10)	P
Sedan
Asthma questionnaire (IQR)	5.9 (4–13)	5.5 (4–12)	5.5 (4–11)	.44
FEV1 (L) (SD)	3.18 (0.95)	3.12 (0.89)	3.13 (0.91)	.11
FEV1:FVC ratio (SD)	0.75 (0.09)	0.76 (0.09)	0.75 (0.1)	.17
FEF25–75 (L/s) (SD)	2.73 (1.28)	2.78 (1.3)	2.68 (1.23)	.42
Mean FeNO (ppb) (SD)	40.85 (64.39)	38.15 (56.37)	39.55 (60.35)	.60
Best PNIF (SD)	137 (50.56)	134.4 (51.41)	139 (55.07)	.51
SUV
Asthma questionnaire (IQR)	5.3 (4–9)	5.8 (4–10)	5.3 (4–8)	.46
FEV1 (L) (SD)	3.09 (0.89)	3.01 (0.86)	3.04 (0.86)	.32
FEV1:FVC ratio(SD)	0.74 (0.1)	0.74 (0.1)	0.74 (0.1)	.49
FEF25–75 (L/s) (SD)	2.63 (1.3)	2.52 (1.33)	2.57 (1.25)	.59
Mean FeNO (ppb) (SD)	35.15 (48.1)	36.15 (48.05)	34.6 (44.23)	.39
Best PNIF (SD)	145 (50.61)	144 (41.42)	143 (43.73)	.98

Abbreviations: FEF25–75, forced expiratory flow at 25%–75% of vital capacity; FeNO, fractional exhaled nitric oxide; FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; IQR, interquartile range; L, liter; PNIF, peak nasal inspiratory flow; ppb, parts per billion; SD, standard deviation.

Discussion

This study has several limitations. The small sample size limits generalizability, although participants were not excluded due to spirometry, FeNO, smoking status, or medication use. Only acute exposure to 2 vehicle interiors was assessed and results may be different with chronic repeated exposure or delayed assessment of symptoms. The tested vehicles may not be representative of all vehicles of the same make and model. The study was completed outside of peak pollen season in Florida, and results may differ during the height of pollen seasons, especially for sensitized individuals. Nonetheless, the study represents a step forward in assessing whether new vehicles affect asthmatics with allergic rhinitis. Patients often complain that new car odors and other strong smells adversely affect their respiratory symptoms. This model system can be used to determine true effects of new car interiors on patients with asthma and allergic respiratory diseases. Future studies should assess nasal symptoms and measure levels of allergens, VOCs, and other irritants in the vehicle interiors after repeated exposures. In addition, asthma phenotypes/endotypes and severity could be assessed in future studies to determine whether a subtype of asthmatics is impacted.

In conclusion, the interior environments of the tested 2017 Mercedes-Benz S-Class sedan and GLE-Class SUV did not cause any significant changes in subjective or objective measures of asthma and allergic rhinitis. We suggest that this model system can be used to test other vehicles for putatively adverse effects on patients with allergic respiratory disorders.