Today, a growing number of countries are battling the rise in both air pollution and childhood hypertension. Often when air pollution and childhood hypertension are discussed, it is as two separate health issues, however, emerging research has shown that they might be more connected then we may think.
Recent studies have suggested that short- and long-term exposure to air pollution can, in fact, elevate blood pressure and increase hypertension risk in children 1,2. Previous research and a report by the World Health Organization found children are highly vulnerable to the effects of air pollution, where exposure as early as in utero can pose serious harm to future cardiovascular health 3–5. With exposure to air pollution being a chief concern among developed and developing countries, the current trend in high blood pressure in children raises apprehension for the future population’s health. For this reason, identifying preventative interventions to lower blood pressure and risk of hypertension in children is a public health priority.
Over the past decades, scientific findings have reported that exposure to pets lowers the heart rate and reduces the risk of hypertension in humans, and is associated with better overall cardiovascular health compared to non-pet owners 6–8. Pet companions have shown to be inhibitors of sympathetic nervous system activity including physiological arousal and behavioral distress 9,10. For instance, research findings have suggested that pet exposure may buffer physiological responses to stress and provide social support that enhances the ability to adapt to stress 10,11. Furthermore, a recent study from the Canadian Healthy Infant Longitudinal Development Study (CHILD) cohort reported that exposure to household furry pets influenced the gut microbiota with increasing the abundance of two bacteria, Ruminococcus and Oscillospira, which have been negatively associated with risk of hypertension such as obesity12.
Though studies have shown exposure to air pollutants is associated with elevated risk of hypertension, while exposure to pets lowers blood pressure, the interaction of both exposures on arterial blood pressure and hypertension risk in children remains unclear.
To fill this gap in knowledge, we investigated if pet ownership would buffer the effect of long-term exposure to air pollutants on blood pressure and hypertension in children. This study analyzed data collected from 9567 school children ages 5-17 years from 24 districts across seven cities in Northeastern China. Children’s height, weight, and blood pressure were measured, and body mass index (BMI) was calculated. Hypertension was defined as average diastolic or systolic blood pressure in the 95th percentile or higher based on height, age, and sex. Pet ownership status was ascertained from parental report, including the number of pets and species, whether children had exposure to pet ownership in utero, during the first two years of life, and currently. Finally, hourly ambient concentrations of particulate matter with aerodynamic diameter of ≤10µm (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), and ozone (O3), as well as daily mean temperature were obtained from monitoring stations that were located away from industrial sources, residential sources, and major roads.
Results showed the association between exposure to air pollutants and hypertension was stronger in children without pet ownership compared to those with pet ownership, especially exposure to PM10 and O3. However, only exposure to O3 interacted with all pet exposure types, and revealed lower blood pressure in children exposed to pet. When examining differences by age, pet exposure was more protective against hypertension among elementary aged children for exposure to all pollutants, suggesting a potential age effect. Additionally, the effects of passive smoke exposures on hypertension was greatest among children without pets compared to children exposed to pets. Interestingly, the buffering effect was generally strongest for pet exposure in utero.
These findings suggest exposure to pet ownership may act as a buffer against hypertension risk in children exposed to air pollutants, especially in utero. However, further research is needed among a more diverse population to understand the etiologic mechanistic interaction between exposures to pet and air pollutants on hypertension risk in children
This research is described in more detailed in the article entitled, Pet exposure in utero and postnatal decreases the effects of air pollutants on hypertension in children: A large population based cohort study, recently published in the journal Environmental Pollution.
This work was conducted by Guang-Hui Dong, Mo Yang, Bo-Yi Yang, Xiao-Wen Zeng, and Li-Wen Hu at Sun Yat-sen University, Wayne R. Lawrence and Shao Lin at the University at Albany, Si-Quan Wang at Harvard University, Yimin Liu at Guangzhou Prevention and Treatment Center for Occupational Diseases, Guangzhou No.12 Hospital, Guangzhou, China, Huimin Ma at Chinese Academy of Sciences, and Duo-Hong Chen at Guangdong Environmental Protection Key Laboratory of Atmospheric Secondary Pollution.
- Zeng X-W, Qian Z (Min) M, Vaughn MG, et al. Positive association between short-term ambient air pollution exposure and children blood pressure in China–Result from the Seven Northeast Cities (SNEC) study. Environ Pollut. 2017;224:698-705. doi:10.1016/j.envpol.2017.02.054
- Dong G-H, Qian Z (Min), Trevathan E, et al. Air pollution associated hypertension and increased blood pressure may be reduced by breastfeeding in Chinese children: The Seven Northeastern Cities Chinese Children’s Study. Int J Cardiol. 2014;176(3):956-961. doi:10.1016/j.ijcard.2014.08.099
- Buka I, Koranteng S, Osornio-Vargas AR. The effects of air pollution on the health of children. Paediatr Child Health. 2006;11(8):513-516. https://www.ncbi.nlm.nih.gov/pubmed/19030320.
- Huang J V., Leung GM, Schooling CM. The Association of Air Pollution With Pubertal Development: Evidence From Hong Kong’s “Children of 1997” Birth Cohort. Am J Epidemiol. 2017;185(10):914-923. doi:10.1093/aje/kww200
- Special Programme on Health and Enviornment. Effects of Air Pollution on Children’s Health and Development. Copenhagen; 2005. http://www.euro.who.int/__data/assets/pdf_file/0010/74728/E86575.pdf.
- Allen K, Blascovich J, Mendes W. Cardiovascular Reactivity and the Presence of Pets, Friends, and Spouses: The Truth About Cats and Dogs. Psychosom Med. 2002;64(5):727-739. doi:10.1097/01.PSY.0000024236.11538.41
- Lentino C, Visek AJ, McDonnell K, DiPietro L. Dog walking is associated with a favorable risk profile independent of moderate to high volume of physical activity. J Phys Act Health. 2012;9(3):414-420. https://www.ncbi.nlm.nih.gov/pubmed/21934154.
- Friedmann E, Katcher AH, Thomas SA, Lynch JJ, Messent PR. Social interaction and blood pressure. Influence of animal companions. J Nerv Ment Dis. 1983;171(8):461-465. doi:10.1007/s00330-011-2364-3
- Hansen KM, Messinger CJ, Baun MM, Megel M. Companion animals alleviating distress in children. Anthrozoos. 1999;12(3):142-148. doi:10.2752/089279399787000264
- Nagengast SL, Baun MM, Megel M, Michael Leibowitz J. The effects of the presence of a companion animal on physiological arousal and behavioral distress in children during a physical examination. J Pediatr Nurs. 1997;12(6):323-330. doi:10.1016/S0882-5963(97)80058-9
- Allen K, Shykoff BE, Izzo JL. Pet ownership, but not ace inhibitor therapy, blunts home blood pressure responses to mental stress. Hypertension. 2001;38(4):815-820. https://www.ncbi.nlm.nih.gov/pubmed/11641292.
- Tun HM, Konya T, Takaro TK, Brook JR, Chari R, Field CJ, Guttman DS, Becker AB, Mandhane PJ, Turvey SE, Subbarao P, Sears MR, Scott JA, Kozyrskyi AL; CHILD Study Investigators. Exposure to household furry pets influences the gut microbiota of infant at 3-4 months following various birth scenarios. Microbiome. 2017; 5(1):40. doi: 10.1186/s40168-017-0254-x.