Air quality in Maryland

Air quality index (AQI) and PM2.5 air pollution in Maryland

Last update at (local time)


Real-time Maryland
Most polluted city ranking

#cityUS AQI
1The national flag of International Charlotte Hall


2The national flag of International Princess Anne


3The national flag of International Chesapeake Beach


4The national flag of International Denton


5The national flag of International Easton


6The national flag of International Pocomoke City


7The national flag of International Centreville


8The national flag of International Chestertown


9The national flag of International Marlboro Meadows


10The national flag of International Saint Mary


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Real-time Maryland
Cleanest city ranking

#cityUS AQI
1The national flag of International Columbia


2The national flag of International Damascus


3The national flag of International Bethesda


4The national flag of International Millington


5The national flag of International Derwood


6The national flag of International Towson


7The national flag of International Takoma Park


8The national flag of International Rockville


9The national flag of International Westminster


10The national flag of International Cockeysville


(local time)


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Where is located Maryland?

Maryland is a state in the Mid-Atlantic region of the United States. It shares a border with five other states and has a substantial seaboard with the Atlantic Ocean. Standing on the shores of Chesapeake Bay, Maryland has over 4,000 miles of shoreline. It is named after Queen Mary who was the wife of the British king, Charles 1. Its largest city is Baltimore and Annapolis is the capital.

Does the air quality in Maryland vary throughout the year?

In 2019, the air quality in Maryland averaged out as being “good” with a reading of 11.2 µg/m³. For four months of the year, it attained the WHO target figure of less than 10 µg/m³. March, May and June saw “Good” quality air with figures between 10 and 12 µg/m³. For the remaining 5 months, the quality was classed as being “Moderate” with readings between 12.1 and 35.4 µg/m³.

Over the previous two years though, the air quality has deteriorated slightly from 8.5 µg/m³ in 2017 and 2018 to 11.2 µg/m³ in 2019.

How does Maryland rank in the air pollution stakes?

Baltimore's air is healthier to breathe than it used to be several years ago, but the region still has some of the nation's worst smog and soot pollution, according to the American Lung Association.

The Baltimore-Washington region also ranked 22nd worst for short-term particle pollution, based on the number of days with unhealthy levels of fine particles or "soot" measured in the air over a 24-hour period.

Nationwide, the lung association says its analysis noted that in America's most polluted cities, air quality was at its cleanest since the organisation began making annual reports over 10 years ago. The group acknowledges regulations imposed under the federal Clean Air Act for reducing pollution from major sources such as coal-fired power stations, diesel engines and large, gas-guzzling SUVs. So, headway is being made in the clean air program.

However, despite these improvements, overall standards in the US are dreadfully outdated and need to be brought up-to-date with new figures reflecting modern technology.

It is reported that more than 127 million Americans which equates to more than 40 per cent of the population, still live in places with dangerous levels of either ozone or particle pollution, or both, which can cause wheezing and coughing, asthma attacks, heart attacks, and even premature death.

The summertime air has noticeably improved since the 1990s, when Baltimore and its surrounding suburbs ranked amongst the smoggiest in the country, trailing only to Los Angeles and New York. In this latest report, it's no longer in the top 10 with the worst ozone pollution.

Where does the air pollution in Maryland come from?

Ozone (O3) and fine particulates (PM2.5) are Maryland’s biggest air barriers when looking at air quality. Both pollutants are created from fuel-burning sources such as vehicles, electric utilities and industrial boilers.

Ozone is a gas that occurs in layers in the atmosphere. When ozone is produced near ground-level it becomes harmful to human health and the environment.

Particle pollution (also called particulate matter or PM) is the term for a mixture of solid particles and liquid droplets suspended in the air. Some particles, such as dust, dirt, soot or smoke are large or dark enough to be seen with the naked eye. Others are so small, they cannot be seen and are invisible under normal circumstances.

Is anything being done to improve the air quality in Maryland?

For the first time in thirty years, Maryland is very close to meeting all federal health-based air quality standards. This is partly due to reductions in emissions from utilities, motor vehicles, manufacturing, and consumer products and has reduced the number of days on which Marylanders breathe unhealthy air.

Maryland has continued to see the percentage of “good” and “moderate” clean air days increase steadily with the help of programs such as the Maryland Clean Cars Program and the Maryland Healthy Air Act. These programs help to reduce emissions from the two major contributors to air pollution which are cars and power plants.

The Maryland Healthy Air Act is one of the most stringent power plant emission laws on the east coast. The Healthy Air Act requires large reductions in nitrogen oxides (NOx) and sulphur dioxide (SO2). The Act also requires control of mercury emissions and greenhouse gases (GHGs). The Healthy Air Act reduces power plant NOx emissions by 75 per cent and sulphur dioxide emissions by 85 per cent at full implementation.

The Maryland Clean Cars Program utilises California’s strict vehicle emission standards. These new car standards became effective in Maryland for model year 2011 vehicles, significantly reducing the number of emissions including volatile organic compounds (VOCs), nitrogen oxides and Greenhouse Gases (GHGs).

Pollution standards in other states upwind of Maryland are just as important to improving air quality as ensuring local pollution sources reduce emissions. Unfortunately, air pollution recognises no state boundaries. Research shows that pollution from upwind states accounts for up to 70 per cent of the ozone levels recorded in Maryland.

Over the past few years, Maryland has been the leading voice in bringing together more than 20 states to try and address this interstate air pollution problem. The U.S. Environmental Protection Agency had to intervene and introduce laws that require power plants that contribute to air pollution in other states to reduce their emissions to levels on par with Maryland.

Maryland power plants are already subject to local regulations that are more stringent than the federal limit.

How is human health affected by the poor air quality in Maryland?

Air pollution is directly attributable to heart and lung problems and even premature death. Large pollutant particles (PM10) in the air can cause irritation and discomfort, while small, fine pollutant particles (PM2.5) from sources such as vehicle exhaust fumes or power plants can penetrate deeply into lung tissue and even enter the bloodstream.

Asthma can cause wheezing, difficulty breathing and coughing. Not everyone who has asthma has these symptoms, and having these symptoms doesn't always mean someone has asthma. It is the most common chronic condition among children and can cause major disruption in a child's life. Many children miss school due to problems linked to their condition. Whilst there is no known cure for asthma, it can be controlled with the correct medication and by the avoidance of things that can trigger an attack.

What options do commuters have which will help reduce pollution in Maryland?

Commuter Choice Maryland is a program funded by the state of Maryland and managed by the Maryland Department of Transportation that provides incentives to encourage people to reduce the impact of their daily commute.

Amongst other benefits, the program provides tax incentives for employers to encourage decreased automobile use for employees and offers a guaranteed ride home for commuters so they are not dependent on a car in case of an emergency. There is a dedicated website where more information can be found.

Train, bus, and even subway services are located throughout Maryland and the surrounding areas. Driving costs and stress levels can be reduced by taking one of these modes to work. There are many park and ride locations throughout the state to provide easy access to these alternatives. Ask your employer to participate in the Commuter Choice Program to provide reduced-price transit passes!

If driving is your best or only option to get to work, an additional rider can help make the commute more enjoyable and reduce costs, too. By alternating driving with other carpool members, you can reduce the amount that you have to drive and be driven to work instead. Try setting up a carpool with others you work with. You can meet at a central location such as a park and ride facility, or be picked up at your house. Be sure to discuss schedule requirements and expenses for gas to keep everyone happy in your carpool.

Commuters who carpool, vanpool, cycle or walk to work and do not need a dedicated paid parking space can ask their employer for Cash in Lieu of Parking. With this program, an employer would provide a cash payment to employers who surrender their own dedicated parking space. Employers who offer Cash in Lieu of Parking can claim a tax credit (up to or equal to $100 per person), making this option a win-win for both employers and employees.

As more and more cycle paths and pedestrian friendly areas are introduced, it is now a possibility to cycle or even walk to work. Depending on circumstances, of course.

Teleworking or working remotely has become the norm during the COVID-19 crisis. Many jobs can now be done from any location as more and more staff work on a computer and connect to the internet by means of communicating with fellow workers. After COVID-19, it is said that many workers will not return to office work in the future but will instead, continue to work from home or telework centres.

Another more unusual suggestion is compressing the working week. This means working an extra hour each day from Monday to Thursday and a standard 8 hour day on Friday. However, over a period of two weeks, the 80 hours will already have been accrued before the second Friday, so that would mean that there is no need to go into work on that day. This saves one day out of ten in commuting. Perhaps this would not be suitable for all staff members but it might be beneficial for some.

Maryland air quality data attribution


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