Ground-level ozone is still damaging your health

Air pollution, Los Angeles-style. Image: Getty.

Ground-level ozone is one of six major pollutants regulated nationally under the U.S. Clean Air Act. It is not directly emitted, but instead forms in the atmosphere through reactions between other pollutants from cars, power plants and industrial sources. Breathing ozone irritates the airways and can worsen respiratory diseases such as bronchitis, emphysema and asthma.

Regulation has reduced ozone levels across the United States over the past four decades, but exposure to ambient ozone still negatively impacts our health, well-being and productivity. In a recent article published in the journal Health Economics, I found that harm from ozone extends well beyond the high exposure levels and sensitive groups that have traditionally been studied. In fact, I identify negative effects of ozone exposure on the performances of intercollegiate track and field athletes under the relatively clean conditions common in the United States today.

These findings suggest that ozone exposure may be imposing harm on people even when they don’t end up in the hospital, and that much of the U.S. public may still regularly suffer some degree of negative impact from ozone exposure.

Hazardous even at low levels

Health researchers have long known that exposure to high levels of ozone is associated with acute negative health outcomes. These include premature death, compromised lung function and cardiovascular issues.

More recent studies have found evidence that ozone also has negative effects at lower exposure levels. For instance, ozone exposures below regulated levels have been shown to contribute to premature deaths and reduce productivity among outdoor agricultural workers. It is also important to note that ozone exposure affects people’s health by inflaming their airways even when functional effects are not measurable.

Ground-level ozone is formed by complex interactions of nitrogen oxides and volatile organic compounds in the presence of sunlight. As a result, ozone levels tend to be highest in summer months. My results are based on outdoor NCAA and NAIA track and field competitions which are held across the contiguous United States during the spring, when ozone levels tend to be below annual maximums.

Ground-level ozone forms through reactions between other pollutants in the presence of sunlight. Image: Minnesota Pollution Control Agency.

Across the approximately 1,700 outdoor track and field meets that I analsed, the average daily ozone concentration was only 33.47 parts per billion, which is well below ambient ozone levels regulated anywhere in the world. For instance, the current eight-hour average National Ambient Air Quality Standard for ozone in the United States is 70 parts per billion, and the current World Health Organization guideline is approximately 51 parts per billion.

But even at the low ozone levels in my study, and among a young and fit population of college athletes, I found consistent evidence that ozone had negative impacts on competitors in endurance events such as the 800 meter run, 3,000 meter steeplechase and 5,000 meter run.

Higher ozone levels, slower race times

Through the analysis of almost 700,000 competition outcomes in 277 different locations over nearly a decade (2005-2013) across the United States, I found that for every 10 parts per billion increase in ambient ozone levels, athlete performance was degraded by 0.4 per cent across endurance events. This effect represents more than five per cent of the average margin of victory in these races, and suggests that there was a 1.5 per cent difference in average athletic performance between the 5th and 95th per centile ozone days in the data.

For a concrete example, consider performances in the 5,000 meter run event. The mean finishing time for men competing in this event was 15 minutes 54.7 seconds. But at meets with average ozone levels above 50 parts per billion, the mean finishing time was 16 minutes 26.0 seconds. The comparable times for women were 19 minutes 5.7 seconds across all ozone levels versus 19 minutes 58.5 seconds at the higher levels.

I found these negative impacts of ozone were larger for longer events in which athletes competed over more extended periods. However, I did not find larger effects for athletes who competed in multiple events. Nor did I observe effects in events which do not heavily tax aerobic capacity.

Ozone in the stratosphere protects life on Earth from ultraviolet radiation, but at ground level it’s a toxic pollutant.

This makes sense because ozone exposure harms the airways and lungs, which are critical to performance in endurance events. They are less important in sprint events, in which muscles can rely primarily on stored energy reserves, or strength events such as the long jump or shot put, which test a single maximum exertion. While athletes in non-endurance events are undoubtedly harmed by ozone exposure, competitive outcomes in such events did not prove useful for studying the damage.

My findings point to risks for anyone spending time outdoors at current ozone levels. According to the U.S. Bureau of Labor Statistics, nearly half of all U.S. jobs require outdoor work. In 2004, nearly 27m Americans were employed in industry sectors in which at least some workers spent much of their workdays outdoors, such as construction, utilities and agriculture. The agency projects that this number will grow to nearly 31m by 2024, representing nearly 20 per cent of the U.S. workforce.


US standards under review

The Clean Air Act requires the Environmental Protection Agency to review and revise national ambient air quality standards regularly to ensure that they protect public health and the environment. Such reviews led to stricter standards for ozone in 1997, 2008 and 2015, lowering the regulatory threshold to 80, 75 and 70 parts per billion respectively.

The agency is currently preparing to carry out its next review of the ozone standard so that any updates can be finalised by October 2020. Earlier this year, then-EPA Administrator Scott Pruitt proposed changes to the review-and-update process that critics argue could weaken standards and threaten public health.

Deregulation advocates often emphasise the costs of complying with tightened regulations. For example, the EPA estimated that reducing the ozone standard from 75 to 70 ppb in 2015 would cost $2.2bn annually. Importantly however, the agency also projected that this change would generate health benefits worth between $4.1 and $8.0bn annually.

A global health risk

Today more than 105m Americans live in one of the 168 counties currently designated as part of ozone non-attainment areas due to violations of the current national ozone standard. The situation is worse in many emerging economies, such as India and China, where rapid industrialisation has led to high and increasing ozone levels.

Climate change is expected to contribute to increases in ozone levels by warming the atmosphere and extending the annual period of high ozone formation from summer into fall. These possibilities, along with findings like mine showing ozone’s impacts even at low levels, underscore the continued importance of effective global monitoring and regulation of ozone and its precursor pollutants.

The Conversation

Jamie T. Mullins, Assistant Professor of Resource Economics, University of Massachusetts Amherst.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

 
 
 
 

To beat rising temperatures, Vienna launches a network of 'Cool Streets'

A Vienna resident cools off at one of the city's new Cool Streets installations. (Courtesy Christian Fürthner/Mobilitätsagentur Wien)

Over the past several months, Austria has recorded its highest unemployment rate since World War II, thanks to the economic aftermath of the Covid-19 pandemic. With no job or a suddenly smaller income – not to mention the continued threat of the virus – many Viennese will opt for a staycation this summer.  

At the same time, last year, Austria’s capital experienced 39 days with temperatures of over 30°C (86°F), one of its hottest summers in history according to the Central Institute for Meteorology and Geodynamics.

Climate experts expect a similarly sizzling 2020 season, and city officials are now doubling down on efforts to combat the heat by launching a “Cool Streets” initiative as well as a new, state-of-the-art cooling park.

“As the city councilwoman in charge of climate, it is my job to ensure local cooling,” Vienna’s deputy mayor Birgit Hebein proclaimed at the opening of one of 22 new “Cool Streets” on 22 June.

“In Austria, there are already more heat deaths than traffic fatalities,” she added.

Hebein was referring to the 766 people the Austrian Agency for Health and Food Security included in its 2018 heat-associated mortality statistics. The number was up by 31% compared to 2017, and in contrast to the 409 people who died in traffic collisions the same year.

The project includes 18 temporary Cool Streets located across the city, plus four roads that will be redesigned permanently and designated as “Cool Streets Plus”.

“The Plus version includes the planting of trees. Brighter surfaces, which reflect less heat, replace asphalt in addition to the installation of shadow or water elements,” said Kathrin Ivancsits, spokeswoman for the city-owned bureau Mobilitätsagentur, which is coordinating the project.


Vienna's seasonal Cool Streets provide shady places to rest and are closed to cars. (Petra Loho for CityMetric)

In addition to mobile shade dispensers and seating possibilities amid more greenery provided by potted plants, each street features a steel column offering drinking water and spray cooling. The temporary Cool Streets will also remain car-free until 20 September.

A sensor in the granite base releases drinking water and pushes it through 34 nozzles whenever the outside temperature reaches 25°C (77°F) . As soon as the ambient temperature drops to 23°C (73°F), the sensor, which operates from 10 a.m. to 8 p.m., turns off the water supply.

The sensors were included in part to allay concerns about legionella, a pathogenic bacteria that can reproduce in water.  

“When the spray stops, the system drains, and therefore no microbial contamination can develop,” said Dr. Hans-Peter Hutter, deputy head of the Department of Environmental Health at the Center for Public Health at Medical University Vienna, in a televised interview.

Hutter also assured the public that there is no increased risk of a Covid-19 infection from the spray as long as people adhere to the one-meter social distance requirement.


But Samer Bagaeen of the University of Kent's School of Architecture and Planning notes that air cooling systems, like the ones used in Germany at abattoirs, have been found recently to be a risk factor for Covid-19 outbreaks.

“The same could be said for spay devices,” he warned.

Vienna’s district councils selected the 22 Cool Street locations with the help of the city’s Urban Heat Vulnerability Index. The map shows where most people suffer from heat by evaluating temperature data, green and water-related infrastructure, and demographic data.

“Urban heat islands can occur when cities replace the natural land cover with dense concentrations of pavement, buildings, and other surfaces that absorb and retain heat,” as the US Environmental Protection Agency states.


A rendering of Vienna's planned park featuring a Coolspot, which is scheduled to open in August. Click to expand.
(Courtesy Carla Lo Landscape Architecture)

Vienna’s sixth district, Mariahilf, is such an area. The construction of the capital’s first “Cooling Park”, a €1 million project covering the 10,600 square-metre Esterházypark, is designed to provide relief. 

Green4Cities, a centre of excellence for green infrastructure in urban areas, designed the park’s main attraction, the “Coolspot”. The nearly 3.40-metre high steel trellis holds three rings equipped with spray nozzles. Textile shading slats, tensioned with steel cables, cover them.

The effects of evaporation and evapotranspiration create a cooler microclimate around the 30 square-metre seating area, alongside other spray spots selectively scattered across the park.

The high-pressure spray also deposits tiny droplets on plant and tree leaves, which stimulates them to sweat even more. All together, these collective measures help to cool their surroundings by up to six degrees.

The landscape architect Carla Lo and her team planned what she calls the “low-tech” park components. “Plants are an essential design element of the Cooling Park,” Lo says. “By unsealing the [soil], we can add new grass, herbaceous beds, and more climate-resistant trees to the existing cultivation”.

Light-coloured, natural stone punctuated by grass seams replaces the old concrete surfaces, and wooden benches meander throughout the park.

Living near the park and yearning for an urban escape close by, Lo says she’s motivated to ensure the park is completed by mid-August.

“If we don't do anything, Vienna will be another eight degrees Celsius hotter in 2050 than it already is,” Hebein said.

Vienna recently came in first in the World's 10 Greenest Cities Index by the consulting agency Resonance.

“There is no one size fits all on how cities respond to urban heat,” says the University of Kent’s Bagaeen, who points out that Vienna was one of the first European cities to set up an Urban Heat Islands Strategic Plan in 2015.

In the short term, prognoses on the city’s future development may be more difficult: Vienna votes this autumn.

Petra Loho is a journalist and photographer based in Austria.