Qualité de l’air à Medford

What is the current level of air pollution in Medford?

Medford is a city in and the county seat of Jackson County, Oregon. A census conducted in 2019 found its population to be approximately 83,100 people. Once the metropolitan area is included, the figure rises to 217,500 which makes it the fourth largest metro area in Oregon.

Looking at figures published by IQAir from August 2021, it can be seen that Medford was experiencing a period of “Unhealthy” air with a US AQI reading of 192. This United States Air Quality Index number is calculated using the levels of six of the most prolific air pollutants, namely, nitrogen dioxide, sulfur dioxide, ozone, carbon monoxide and both sizes of particulate matter, being PM2.5 and PM10. It can be used as a standard when comparing air quality in other cities around the world. If data is unavailable for all 6 pollutants, a figure can still be calculated by using what figures there are. The only record available in Medford was that of PM2.5 which was 134.7 µg/m³. The World Health Organization (WHO) has a recommended level of 10 µg/m³, so with this figure, it is seen to be over 13 times the WHO suggested maximum.

With pollution at this level, the recommendations would be to stay indoors and close all doors and windows to prevent the ingress of more polluted air. An air purifier would be beneficial if one is available. Avoid exercising outside until the quality improves and if venturing outside is unavoidable, then wearing a good quality face mask is essential. The table that is published at the top of this page should help with that decision or download the AirVisual app for constant updates as to the state of the air in real-time.

Is the level of pollution consistent throughout the year?

Having consulted the table of figures published by IQAir.com for 2020, it can be seen that September was the month with the worst air quality. The recorded figure was 92.4 µg/m³ which classified it as being “Unhealthy”. Any reading between 55.5 and 150.4 µg/m³ would fall into this bracket. The subsequent three months of October, November and December saw an improvement when the air was “Moderate” with figures of 17.6, 14.1 and 14.0 µg/m³ respectively. The remaining seven months achieved the target figure of 10 µg/m³ or less as recommended by the World Health Organization (WHO). The cleanest month was June with a small figure of just 3.0 µg/m³. April and May were close behind with 4.5 and 3.3 µg/m³, respectively.

Historically, figures have been kept since 2017 when the figure recorded was 15 µg/m³, which was “Moderate”. A similar quality was recorded for 2018 with 22 µg/m³ which again, was “Moderate”. A noted improvement was seen in 2019 when the figure of 8.7 µg/m³ achieved the WHO target figure. However, in 2020 the quality slipped back into the “Moderate” classification with a figure of 15.8 µg/m³. This figure is quite surprising because of the restrictions imposed by the COVID-19 pandemic. Many vehicles were temporarily unused as their drivers were not required to work from the office, instead, they were furloughed and allowed to work from home. This had the effect of drastically reducing pollution within the city center. Many small factories and non-essential production units were also closed which again lead to an improvement in air quality. Yet, for some reason, Medford recorded the worst annual average figure since records began.

What are the sources of this air pollution in Medford?

The Oregon Department of Environmental Quality and Lane Regional Air Protection Agency published recent data which shows historical record-breaking poor air quality across the state. Oregon has been affected by some of the worst air quality in the world with such dense concentrations of tiny particles from wood smoke that it’s been considered unhealthy or even hazardous to breathe. Unfortunately, Medford was mentioned by name alongside four other cities in the vicinity.

Vehicles and industry also contribute to the poor quality air in Medford but not to the great extent of twenty years ago. Now, due to new pollution control technology on vehicles and industries and the development of other pollution prevention programs, Oregon hasn't had a carbon monoxide violation in years.

In the 1970s several strategies were put into place to clean up the air. They focused on cars and trucks. This included new federal emission standards for vehicles, the launch of the vehicle inspection program and transit improvements. Other efforts included reformulating gas to make it less polluting and placing additional regulations on the industry.

A large number of pollutants are emitted near road infrastructure and come not only from vehicle exhaust emissions but also from other sources such as tire and brake wear, vehicle air conditioning technologies, 'wear and tear of roads and the upkeep of their surroundings (use of phytosanitary products, etc.). To these so-called “primary” pollutants because they are emitted directly by pollution sources, there are also so-called “secondary” pollutants, such as particles, resulting from chemical reactions between pollutants occurring in the atmosphere.

In 2019, road transport represented around 12%, 54% and 40% of metropolitan average emissions respectively of fine particles PM2.5, nitrogen oxides (NOx) and black carbon or soot, these proportions can be locally greater, in particular near junctions with heavy road traffic. In addition, it should be noted that these polluting discharges generally occur near inhabited areas and at ground level, which leads to a high potential for exposure of the population to polluting emissions from road traffic.

Fine and ultrafine particles can be easily transported from wildfires over long distances that can reach several hundred kilometers or more, and particle compounds such as soot ("black carbon") and organic carbon, the combustion of biomass (wood) cause the emission of various gases with toxic potential for human health in the outside air and which are in particular carbon monoxide (CO), nitrogen oxides (NOx), volatile organic compounds (benzene, formaldehyde, acrolein, etc.), polycyclic aromatic hydrocarbons (aldehydes, phenols, etc.), metallic elements (mercury, arsenic, lead, etc.), dioxins and furans.

Industry is a major source of air emissions. The use of electricity does not emit pollutants at the place of consumption, but it very often generates emissions at the place where this electricity is produced. Examples of pollutants emitted by this sector are sulfur dioxide, dust, metals and volatile organic compounds (VOCs).

Can anything be done to improve air quality in Medford?

During the COVID-19 pandemic, the decline in many social and economic activities resulted in reduced emissions and subsequent levels of some air pollutants. For example, during times of lockdown, vehicle use had declined, resulting in lower nitrogen dioxide concentrations in many cities. Exposure to air pollution is correlated with cardiovascular disease and respiratory disorders, two health impairments are known to increase susceptibility to COVID-19 and have negative consequences on the prognosis.

Particulate matter, nitrogen dioxide (NO₂) and ground-level ozone (O₃) are the pollutants that cause the most damage to human health and the environment. These pollutants are mainly emitted by road transport, residential heating, agriculture and industry.

In cities, road transport is often the main source of air pollution, in particular, because cars emit pollutants at ground level, in the layer of air breathed by people.

What all sources of air pollutants have in common is that they are deeply rooted in the fundamental systems of our societies for mobility, production and consumption of energy and food. These same systems are not only the main sources of air pollutants but also the root causes of the climate crisis and the rapid erosion of biodiversity.

Various measures are available to those local authorities who wish to reduce air pollution. Such measures could be the development of district heating networks, encouraging cycling as a means of transport, reduced speed limits and imposed city tolls to improve air quality at the local level. Other successful initiatives could include the relocation of industrial facilities, the modernization of domestic heaters, the use of cleaner fuels for heating, the transition to cleaner buses and trams and the introduction of low-emission transport zones. The electrification of private vehicles is also something to be encouraged.

Rogue Valley usually experiences the worst air quality due to the smoke from wildfires which usually occur between the end of June and the start of September. Over the past 20 to 30 years the air quality in the Rogue Valley has greatly improved. Very fine particulate matter (PM2.5) has dropped below the National Ambient Air Quality Standards and ozone pollution has dropped as well. In the past, Rogue Valley has had trouble meeting air quality standards, but now excluding wildfire smoke has met standards consistently. This is mainly due to the topography of the valley which is prone to temperature inversions that trap smog and pollutants in the lower levels of the atmosphere. This is especially noticeable in the cooler months of the year.

Improved air quality has been a group effort, that residents have played their part by reducing the frequency of open burns and industries for increasing their monitoring of emissions.

What are the detrimental effects of air pollution in Medford on our health?

Many residents experience some type of air pollution-related symptoms, such as watery eyes, coughing, or noise when breathing. Even for healthy people, polluted air can cause irritation or breathing difficulties during exercise or strenuous outdoor activities. The actual risk depends on your current health status, the type and concentration of the pollutant, and the length of time you have been exposed to the polluted air.

The US Environmental Protection Agency (EPA) has found that, contrary to what was previously believed, people's health is affected by lower levels of ground-level ozone and particulate matter.

Scientific evidence indicates that lung damage that is caused by prolonged exposure to lower levels of ozone-polluted air poses the greatest health risk. Averaging ozone levels for eight hours provides a higher level of protection, especially for children and those adults who spend a significant portion of their time working or playing outdoors which is a group that is particularly vulnerable to the effects of ozone.

The standard for airborne particulates up to 10 microns in diameter (PM10) remains in effect. But now, the EPA says that air pollution with smaller particles measuring less than 2.5 microns in diameter (PM2.5) is also a health concern. Breathing air polluted with fine particles can have detrimental health effects - including premature death and an increase in respiratory illnesses.

The term fine particles, or PM2.5, refers to tiny particles or droplets in the air that are two and a half microns or less in width. There are about 25,000 microns in an inch. The widths of the larger particles in the PM2.5 size range would be about thirty times smaller than that of a human hair. The smaller particles are so small that several thousand of them could fit on the period at the end of this sentence. Particulate Matter is a complex mixture that may contain soot, smoke, metals, nitrates, sulfates, dust, water and tire rubber. It can be directly emitted, as in smoke from a fire, or it can form in the atmosphere from reactions of gases such as nitrogen oxides.

Particles in the PM2.5 size range are able to travel deeply into the respiratory tract, reaching the lungs and traveling as far as the alveoli where they can then transfer across into the bloodstream. Exposure to fine particles can cause short-term health effects such as eye, nose, throat and lung irritation, coughing, sneezing, runny nose and shortness of breath. Exposure to fine particles can also affect lung function and worsen medical conditions such as asthma and heart disease. Scientific studies have linked increases in daily PM2.5 exposure with increased respiratory and cardiovascular hospital admissions and deaths. Studies also suggest that long-term exposure to fine particulate matter may be associated with increased rates of chronic bronchitis, reduced lung function and increased mortality from lung cancer and heart disease. People with breathing and heart problems, children and the elderly may be particularly sensitive to PM2.5. Both groups have lower immune systems due to their respective age. Pregnant women also fall into this high-risk category as do people who work outside on a daily basis. People in these groups may experience health impacts at lower air pollution exposure levels, or their health effects may be of greater intensity.