Latest scientific research: a healthy community can be walked and green

Author: Kaid Benfield

There is growing evidence that the shape and characteristics of our communities have a major impact on our health. Among the characteristics of community neighborhoods, walking alone is not enough. To be truly healthy, especially in cities, we also need the natural environment of our community. This issue will introduce the latest research on the relationship between community health and the natural environment published by Kaid Benfield.

Urban health risk

Urban life can alleviate some health conditions, but it often exacerbates other situations. On the bright side, cardiovascular health rates are generally better in cities than in rural areas. The downside, however, is that urban residents also experience higher concentrations of air pollution, so they may be at greater risk of respiratory illness.

For example, a study published last year showed that among 3,509 Canadian children living in urban and rural areas, the prevalence of asthma in urban areas was generally high, with signs that along the gradient from rural to urban areas. The incidence of asthma tends to rise . This is consistent with previous studies of adult asthma in the UK. (But a study published by Johns Hopkins in 2015 found that the incidence of childhood asthma in urban centers in the United States may be “explained by demographic factors,” especially poverty, rather than living in urban communities.

In addition to asthma, the scientific view of the harmful effects of urban noise pollution is clear. Reporter Matthew Keegan wrote some of the effects in the "Guardian" article in March 2018:

“The World Health Organization (WHO) says noise pollution is an underestimated threat that can lead to hearing loss, cardiovascular problems, cognitive impairment, stress and depression...”

A recent study by experts at the American College of Cardiology found that noise pollution is associated with cardiovascular problems (hypertension, heart disease, heart disease, stroke, coronary heart disease) through body-pressure-induced reactions, and noise pollution will result in The release of the stress hormone cortisol, which in turn damages blood vessels."

The study also found that, on average, the hearing loss of a person living in one of the most noisy cities in the study was equivalent to the hearing loss of an elderly person aged 10 to 20.

How much noise is required to cause health problems? According to a study detailed in my previous article, cardiovascular effects begin to appear after exposure to 65 decibels. This is between the levels of typical large offices and highway traffic. Depending on the duration of exposure, hearing impairment can start at approximately 85 decibels, roughly equivalent to a noisy restaurant or traffic jam. The noise level on the New York City subway platform has been measured at 108 decibels and has risen to 112 decibels in the car.

Urban and mental illness

These conclusions are consistent with the investigators' review of the high methodological quality of 20 of the 110 studies in Amsterdam that adjusted for important confounders, and the complex quantitative meta-analyses that reflect differences in urban-rural mental health. The researchers combined data from 20 leading-edge studies from relatively high-income countries and found that the incidence of mood disorders (mainly depression) was 39% higher, and the incidence of anxiety disorders was higher in urban areas than in rural areas by 21% . Even if the data is controlled by other factors, including age, gender, marital status, social class and ethnicity, there are significant differences. (The researchers looked for but did not find significant differences in the substance abuse of urban and rural residents.)

As we expected, all of these problems will intensify in low-income areas. People in poor communities need to treat asthma, diabetes and cardiovascular disease twice as often as wealthy communities ,” Shelterforce's Kevin Barnett reports. Erin Schumaker wrote in HuffPost that those who have experienced changes in low-income areas, They face additional negative health effects of construction, such as noise, particulate contamination, lead exposure, air toxins and stress, and anxiety about the affordability of families and the stability of long-term social networks.

But there is also good news.

I think all of this depicts a negative portrait of a city life. However, as more and more research shows that the urban environment can be very supportive of health if we keep the community functioning properly. And walking is the best community feature to start this.

Over the years, my most recognized connection to pedestrian neighborhoods and health research has been a large-scale study in Utah in 2008. Using driver's license data, the researchers collected the height, weight, and address of 453,927 adults living in Salt Lake County and correlated these data with the walking characteristics of the subject's residential area. Based on the summary posted on WebMD, they found these:

“Based on the analysis, men who live in Salt Lake City's most pedestrian-friendly community are expected to average 10 pounds lighter than men living in the most inaccessible community. For women, the gap will be 6 pounds.”

In particular, researchers led by Dr. Chinmoy Sarkar of the University of Hong Kong found that community-based walkability and contraction based on residential and commercial density, comprehensive indicators of public transport availability, pedestrian activity, and proximity to attractive destinations Lower pressure, lower diastolic blood pressure and lower incidence of hypertension.

Pedestrian properties

So, what constitutes a pedestrian block? In the recent popular web-based application, Walk Score, some influencing factors are set, including distances from a given address or community to facilities such as shops, parks, schools, and transit stations; population density; street indicators such as blocks Length and intersection density, etc. (Shorter blocks and more intersections tend to promote shortcuts and reduce the walking time and distance to the destination on average.) The walking score is calculated from 0 to 100 for each position, and any result with more than 70 is rated as " Very suitable for walking"; blocks above 90 points are considered to be "walkers' paradise".

A review of the literature in the PPS report cited above found that “ 80% of the relevant studies on community attributes that encourage walking”, 80% believe that the presence and proximity of local stores, services and transportation sites are most closely related to transportation rates. 50% believe that there are closely connected sidewalks and streets .” In 2016, in the international study of 6,822 adults in 14 cities (including ten countries; including Baltimore and Seattle in the United States), everyone was wearing electronic sports surveillance. The four statistically significant land-use characteristics were identified: residential density, cross-density, public transport density, and access to parks within a half-kilometer range, associated with moderate to severe levels of physical activity : one also needs to feel a The community is safe, including motor vehicle traffic that can be voluntarily walked. The PPS report continues:

“An assessment published by Active Living Research in 2015 found that traffic safety (and crime) is one of the most important factors in attracting people to travel and encouraging walking. This sense of security is also related to sidewalks, sidewalks, pedestrian infrastructure, streets. Connectivity, controlled intersections, clearly marked road intersections, and reduced traffic speed and traffic volume."

But another recent large-scale study (October 2017), led by Dr. Chinmoy's team and using the same UK database as the UK blood pressure study, found that the single factor of residential density, with reduced body fat and obesity Related . The effect is from 1800 residential units per square kilometer (approximately seven units per acre), starting from 3,200 units per square kilometer (approximately 13 units per acre). (Below the threshold of 1800 units per square kilometer, the increase in density does not help.)

About urban nature

On the other hand, while research on walkability is getting stronger, research on urban nature and health is increasing.

For example, a newly published (December 2017) study in the British medical journal The Lancet was summed up by Stephen Schmidt on Science Friday: the researchers brought together 135 subjects aged 60 or older. They were divided into (1) healthy, (2) patients with chronic obstructive pulmonary disease (COPD), and (3) patients with ischemic heart disease (where coronary artery occlusion reduces myocardial blood supply). Participants were then randomly assigned to Oxford Street, London, one of the city's most active cities, or two hours walk in the city's Hyde Park. The researchers measured heart and lung function before and after exercise.

Subjects who walked through the park showed significant improvements in lung function and cardiovascular function, whether healthy or chronic; those walking along Oxford Street showed a negative impact on these indicators. Researchers believe that the reason for this difference is exposure to air pollutants along the streets of Oxford, especially nitrogen dioxide and ultrafine particles. Researchers led by Dr. Rudy Sinharay of Imperial College London have concluded that:

“Our findings suggest that healthy people and patients with chronic heart and lung disease should minimize walking on highly polluted streets, as this will weaken or even reverse the benefits of exercise on the heart and lungs. Instead, walk away from high-density traffic in urban green areas. motion."

Urban nature and longevity

In addition, in two large-scale, well-controlled recent studies, each study showed that residents of green neighborhoods lived longer than other residents. In the largest and most recent (October 2017) study, Canadian researchers led by Dr. Dan Crouse of the University of New Brunswick examined a large database of approximately 1,256,000 people, a national representative representing the Canadian Census. Sex sample, representing Canada's 30 largest metro area. The census information and tax return data (controlling socio-economic factors), the Canadian mortality database and the now standardized satellite color measurement of neighborhood greenness are called the “normalized vegetation index (NDVI)”.

The researchers examined the data from the cohort for a decade and found that “ when the green coverage of the community is measured between 250 and 500 meters, the mortality rate is 8-12 in the case of increased greenness around the investigator’s place of residence. The range of % has decreased. Greener communities have been found to be most beneficial to respiratory diseases. The researchers pointed out that "controlling environmental nitrogen dioxide levels is beneficial to improve respiratory diseases. ”

These results are consistent with a 2016 study that conducted a database check of 106,630 women who participated in a US-based National Nurse Health Study during an 8-year period of 8,604 deaths. Health, mortality, and socioeconomic data were compared to NDVI measurements near each household's place of residence within 250 to 1250 meters (1250 meters approximately 15 minutes walk).

Before ending the theme of green neighborhoods and physical health, I will mention two other studies that provide specific findings about trees. The first, led by the University of Exeter and published late last year, examined more than 650,000 cases of severe asthma attacks and emergency hospitalizations in 26,000 urban communities in England within 15 years. The researchers looked at trees and other forms of green spaces and gardens in the patient's living area, as well as air pollution levels, and found that trees were less associated with emergency asthma cases in contaminated communities, but other types of green plants did not. However, in communities with low levels of pollution, the opposite is true: gardens and green spaces are associated with a lower incidence of asthma emergencies, but trees are not .

The second study investigated self-reported health information from 31,109 residents in Toronto, correlating the results of the survey with local vegetation data and finding that “ people living in neighborhoods with high density of trees on the street have a sense of health.” Significantly higher, cardiovascular metabolic problems are significantly reduced (limitation excludes socioeconomic and demographic factors) .

Urban natural and mental health

Despite the rapid development of research organizations that study the relationship between the natural environment and physical health of the neighborhood, the science that proves the benefits of nature for mental health has long been established. The following is an excerpt from a recent literature review of the subject, which was conducted in response to a study published in the Oxford University publication "Biosciences":

“ Although urban residents are at higher risk of mental illness, there is increasing evidence that natural features in the built environment can offset the harmful effects of urban life and even promote mental health. For example, living in trees, gardens, Urban areas with natural landscapes such as parks, birds and water have higher levels of mental health and lower incidence of chronic mental illness."

In addition, when I studied the book People Habitat published in 2014, I discovered that a monograph published by the National Amusement and Park Association in 2010 reported an impact on the mental health of communities with and without green spaces. Large Dutch research report. It finds a direct relationship between mental health effects and park proximity:

“Netherlands scientists have studied the prevalence of anxiety disorders in more than 345,000 residents and found that people living in the smallest residential areas with green areas are 44% more likely to be diagnosed by physicians than those living in green housing areas...

“The time spent in the lush green environment also reduces grief and depression. In the Dutch study, doctors diagnosed the area with the highest prevalence of depression in residential areas as the area with the least green area.”

The NRPA report even cited research that found that in Chicago's residential projects with green landscapes, the level of attack, violence, and crime was lower than in projects without green landscapes .

A frequently cited benefit of neighborhood green spaces is that they tend to bring us together and reduce loneliness. A survey of Canadians aged 55 and over published last year showed that they were particularly concerned about loneliness and found that “the combined effect of living near a park and going to a park often is about the same as reducing loneliness when getting married.” For comparison The purpose of living nearby and frequent visits to the library is also very beneficial in reducing loneliness. "But it is not as important as the benefits of living near a park." The same is true for living near “high quality” public transportation.

Action taken

There are more and more cases of joint research on urbanity and nature. To this end, I am very encouraged by a report by Kat Friedrich of Green Katz (June 2017), who pointed out that health care giant Kaiser Permanente has collaborated with the University of Illinois and the government, non-profit organizations and business associations on a large-scale research collaboration. Among the 4 million users in Northern California, satellite imagery determines whether greening near homes (category 3: street trees; park spaces and private gardens) can make measurable differences in user health.

Friedrich quoted Matt Browning, a researcher at the University of Illinois:

“We expect to invest in urban green space in terms of reducing health care spending from 1:10 to 1:100. This means investing $1 to grow and maintain urban trees can reduce nearby health care costs by $10 to 100. Dollar."

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