Air Pollution 101
Ozone, or smog, is a dangerous pollutant that poses a serious threat to human health. It is not emitted directly into the air, but rather is created through a process of chemicals, nitrogen oxides (NOx) and volatile organic compounds (VOCs) that combine in the air and are heated by the sun to form ozone.
Houston’s weather and location is perfect for the formation of ozone. Ozone is formed on warm, sunny days with little to no wind and no rain. But the sea breeze coming from the Gulf of Mexico also helps move the ozone polluted air around the Houston region. In the early morning the winds come from the Northwest carrying pollution from the Houston Ship Channel (where a large concentration of NOx and VOCs have been measured) and push these pollutants out to sea. When the afternoon temperatures heat up, the winds switch directions and move clockwise carrying the pollutants north of the city. This is the reason the Texas Commission on Environmental Quality (TCEQ) have measured high ozone levels in areas like Fort Bend County Ozone can form in temperatures as low as 75ºF, and Houston has several days per year that reach temperatures above that. However, due to other meteorological conditions, Houston’s ozone season really heats up between the months of March through November, with the highest levels of ozone forming in August and September.
Sources of NOx and VOCs include: petrochemical refineries and plants, construction equipment, power plants, breweries, bakeries and restaurants, dry cleaners, marine vessels, planes, trains and automobiles. And yes, trees and plants also emit some of the chemicals
Good up high, bad near by. Ground-level ozone, or bad ozone, is the same as the chemical structure as the earth’s protective ozone layer (or the good ozone), which helps protect us from high levels of the sun’s ultraviolet rays. But it’s harmful for humans to breathe ozone.
Breathing ozone can trigger health problems. Chest pain, coughing, irritated throat and nose are some of the symptoms brought on by ozone. And it’s especially harmful to children, the elderly and people who suffer from respiratory illnesses like asthma, bronchitis and emphysema. Recent studies have shown that exposure to high ozone levels can cause complications for people who have cardiovascular disease and can even lead to heart attacks. Ozone, however, does not cause cancer.
Children are particularly susceptible to ozone pollution because their lungs are still growing. Extended exposure to ozone can lead to scaring of the lungs.
Reducing your risk of exposure may require you to change your daily activity on days with high ozone. Here are some suggestions.
- Avoid outdoor activities and exercise indoors. This is especially important for those most vulnerable like children, elderly and those with existing respiratory illness.
- Mow your lawn in the late afternoon or early evening.
- Carpool, ride mass transit, walk or ride your bike to reduce the number of vehicles on the roads, especially in the hot summer months.
The Air Quality Index (AQI) is an important tool to help you know what precautions to take on days with high ozone formation. Many meteorologist report high ozone alerts and refer to the AQI during their weather report.
You can sign up to receive ozone alerts via email by going to the following Web sites:
- Harris County Office of Emergency Management
- Texas Commission on Environmental Quality (TCEQ)
- See the attached document, Ozone 101, for further information, and don’t forget to forward it to friends and family so they can learn about ozone too.
What are Air Toxics?
Air toxics are hazardous air pollutants that have a serious negative impact on human health, like causing cancer, reproductive effects or birth defects.
The U.S. Congress amended the Clean Air Act In 1990 to allow the Environmental Protection Agency (EPA) to oversee the control of 188 hazardous air pollutants (HAPs) in order to protect human health. The EPA works with local and state governments to implement technologies that control the emission of these chemicals.
Because Houston is home to many of the largest petrochemical facilities in the U.S. and the world, Houston unfortunately has many different HAPs in our air. Of the EPA’s 188 HAPs, 161 are present in varying concentrations at different locations in the Houston area.
Air toxics like 1,3-butadiene, used to produce different kinds of rubber products such as tires, and benzene, found in gasoline, can reach annual levels many times higher than in other major U.S. cities, according to a 2006 study by Rice University (view study).
Communities that are most at risk of developing health effects from air toxics are the neighborhoods located in close proximity to petrochemical plants and refineries. These areas are called fenceline communities because they are literally in the backyard of some major industrial facilities. The Manchester community located in Houston’s East End is one of these fenceline communities.
Air Alliance Houston is working with local elected officials and regulatory agencies, as well as other environmental groups to promote new technologies that can be implemented to significantly reduce the harmful emissions of air toxics.
Go to Air Alliance Houston Reports to view a new report on air toxics “Houston We Have a Problem: A Roadmap for Reducing Petrochemical Industry Toxic Emissions in the Lone Star State.” Toxic Texas
What is Particulate Matter?
Particulate matter (PM) is a mixture of solid particles and liquid droplets. Fine particles are a subset of this group, and consist of particles with a diameter or 2.5 microns or less. (A human hair has a diameter of 70 microns). Sources include diesel and gasoline engines, dust and smoke, power plants, petrochemical refineries and plants.
Diesel particles, or soot, make up a significant portion of our fine particle air pollution and are classified as an air toxic. They can cause chronic disease and contribute to the risk of developing cancer at any concentration. In fact, they carry the highest additional cancer risk of any air toxic in the Houston area.
The Clinton Drive area is one community most at risk for fine particle pollution in the Houston region. The air quality monitor in this area indicates that the PM problem has exceeded federal health standards for fine particles. Air Alliance Houston, along with other nonprofit groups such as Environmental Defense Fund, has been leading efforts to address the PM2.5 problem in the Clinton Dr. area.
Ultrafine diesel particles are so small that they can enter the bloodstream from the lungs and can cause different types of cancer. PM can also lead to other illnesses like cardiovascular illness; stroke; nervous system impairment; and respiratory illnesses including asthma, respiratory infections, and allergy symptoms. Diesel PM can even cause death. Texas is 5th in the U.S. for premature deaths from PM.
Educational video broadcast prgrams on the different air pollutions from AIRNow.gov. Click here.