Weather Spectrum

Houston Air Quality Alerts

By: LPerezIII, 2:24 PM GMT on April 26, 2012

I returned to Houston six months ago after being in Omaha, NE for nearly five years during which time I had almost forgotten what an Air Quality Alert was. It didn't take long after my return to see the first one issued in late March. I honestly do not remember seeing alerts for bad air quality that early in the year when I was younger, but I suppose it did occur occasionally. However, it is undoubtedly getting worse as Houston's population continues to grow and expand.

A quick aside: The population in Houston's MSA (Houston, Sugarland, & Baytown) in 1970 was 2,201,849. That grew, on average, 3.55% per year to 3,767,218 in 1990. Today the population sits at an estimated 6,086,538 representing an average growth rate of 2.9% since 1990. We'll come back to these stats in a bit.

To understand why the public has to contend with poor air quality is not a mystery. In fact, all I have to do is look along the horizon on a clear, wind-less, morning and I can see the culprit very clearly as I crawl to work in rush hour traffic. It's that nasty brown layer that seems to hug the horizon in every direction. That visible layer is also known as smog. The early morning Houston smog is a result of the chemical "leftovers" that every combustion engine releases into the atmosphere. Our cars, planes, buses, construction equipment, refineries, and anything else that involves burning a combustible fuel all contribute to smog, albeit some more than others. However, it is a necessary evil. We all have to work and many of us have to commute to our jobs each day. Refineries have to refine the fuel we use in our vehicles. Airplanes have to carry vacationers along with business women and men while using the refined fuel to fly them around. And so on, and so on.

The Stats

Today, in Houston's metro area, including Sugarland and Baytown, there are about 6,100,000 people. Let's assume approximately 45% commute to and from work each day (at least 20 round trip miles). That's a whopping 2,745,000 vehicles traversing Houston metro streets twice a day. That does not include air traffic, boat traffic, freight truck traffic, and others. It's probably a pretty safe estimate too considering 91% of Houston households have at least 1 car (35% have 2 or more). The average household is 2.83 people. That equates to about 2,155,000 households in the metro. 15% are retired people. Therefore, 1,831,750 are working class that have 1,282,225 cars (35% times number of working class households times 2 cars), and then 1,190,637 for the remaining 65% of working class households with one car. Take into account unemployment of 8%... CONSERVATIVELY, 2,275,033 vehicles of working class citizens with jobs are driven each day. Not including commuters from other cities not part of the metro population. No matter how you slice it, there are multiple millions of vehicles traveling Houston's streets every single day. Along with the 2,300 or so commercial flights every day (airline stats). And it's only getting more congested.
The following table reveals how much annual pollution is emitted by a passenger car (estimates as of year 2000).

Using 2,275,000 vehicles from the calculation above, which we know is conservative, and the table above, here are some figures to consider.

Per Year, Houston traffic contributes at LEAST:

87,701 Tons of Hydrocarbons

654,062 Tons of Carbon Monoxide

43,452 Tons of Oxides of Nitrogen

13,024,375 Tons of Carbon Dioxide

TOTAL ---> 13,809,590 Tons of Pollutants

AND 1,321,775,000 Gallons of Gasoline

(multiply # of Gallons above by avg. gas price of $3.75 ) -- Wowza!

13,809,590 TONS of Pollutant each year, conservatively, solely by the vehicular traffic in the Houston Metro. That's equivalent to 24 of the largest oil tankers in use today filled to the max with pollutants and delivered to the city each year. No wonder why the pollution is visible daily. 37,834 tons get released into the atmosphere each day!!

Now that we have some very rough idea of the amount of pollution generated solely by vehicular traffic, and we know it is millions of tons worth a year. What actually causes the air quality alerts? After all, it's not everyday we have bad air quality even though about the same amount of pollution fills the atmosphere daily.


When the sun's ultraviolet rays come into contact with the molecules of the various pollutants that are suspended in the lower atmosphere it causes them to react with each other to form new, more harmful, molecules. Specifically, when the reaction forms the gas Ozone which is 3 oxygen atoms combined - that is bad news. Right now, and every time you take a breath, the oxygen atoms you breathe are made up of a diatomic oxygen molecule meaning it is composed of 2 atoms of oxygen (O2). You'd think adding a third atom would be better in a sense. It's more oxygen right? Yes. Unfortunately, it's not a healthy form of oxygen. Ozone, O3, without going into too much detail here, causes inflammation of the walls of the lungs exacerbating symptoms of those with existing lung disorders such as asthma, emphysema, bronchitis, and other lung problems. If the ozone concentration is extreme enough even healthy people will begin coughing and experiencing difficulty breathing if outdoors for some length of time beyond 30 minutes or so. The most frail, babies and the elderly, can actually experience severe enough problems to cause hospitalization most extreme circumstances. Read all about the health effects in more detail here.

Other environmental factors that exacerbate the levels of Ozone are temperature, wind speed, wind direction, and a strong inversion in the lower atmosphere. When the temperature increases during the daytime it acts to increase chemical reactions. So temperatures into the 90's or 100's can send the level of ozone into the extreme range in no time. That is mainly why the worst air quality days occur in the summer months. Wind is important because it can act to disperse the concentration of pollution through mixing in the lower atmosphere and carry it away from populated areas. Strong winds lead to decreased Ozone. Light winds or no wind is a recipe for bad air quality. Wind direction plays a role as well by transporting pollution from industrial areas into the city or rural areas. The largest refineries are east of the city, so a very light breeze from the east can send pollution and the resulting ozone into the extreme category over the city or rural areas in a short period of time. Lastly, an inversion acts to trap air in the lower portion of the atmosphere and prevents mixing which would help dissipate the pollution quicker. If the pollution gets trapped overnight and more pollutions accumulates the next day, when temperatures rise Ozone concentration will too and possibly become extreme by peak heating time in the afternoon.

Because of the potential for adverse health effects as a result of ozone formation, the Texas Commission on Environmental Quality (TCEQ) monitors the ozone levels in Texas and in the Houston Metro. The National Weather Service through the TCEQ issues air quality alerts.

Unfortunately, this is the way of life in a city as large as Houston. And Houston is one of many cities in the nation with Ozone pollution. According to WebMD, Houston is No. 8 on the list of cities with unhealthy air quality. That's up from No. 4 though; some good news there. og-cities

As summer approaches temperatures will rise and the wind will subside. That's when Houston can expect many more Air Quality Alert days. It's best to keep the little ones and old/wise ones indoors during the hottest and sunniest part of the day and limit overall outdoor exposure on days when the air quality is going to be dangerous.

Today's Current Ozone Level (Courtesy TCEQ)

Check back often as I will be updating on expected severe weather and tropical weather as it occurs. On uneventful weather days I'll be composing random weather related blogs for your entertainment.

Thanks for reading!





Hurricane Season 2012

By: LPerezIII, 8:12 PM GMT on April 19, 2012

It’s approaching quickly and the opinions are in. Colorado State has published the extended outlook for the 2012 season. They predict 10 named storms with 4 hurricanes and 2 major hurricanes (6 hurricanes in all). For comparison, an average season consists of 12 named storms, 6-7 hurricanes, and 2 of those as major hurricanes.

The forecast below-average season is due to the potential development of El Niño this summer. Currently the ENSO (El Nino Southern Oscillation) is Neutral. When the oscillation moves towards El Nino (warmer than normal water temperatures in the east Pacific) that typically brings dry air into the Atlantic Ocean, increased wind shear, and diminishing moisture thus hindering tropical development.

The picture below shows ENSO Neutral conditions in the top photo (1993) and ENSO El Nino in the second photo (1997).

This is a map of the hurricane tracks of all storms in 1997. The Gulf was almost storm-free during the record El Nino event that year.

This is the Sea Surface Temperature anomaly as it is today…

You can definitely see the warming in the waters on the west coast of South America, indicating a transition to El Nino is coming. How strong it will be is currently unknown. As is when it will officially be classified as El Nino. A certain threshold of Sea Surface Temperature anomaly must be reached first. By the way, the Gulf is extremely warm for this time of year, upwards of 4 degrees higher than normal! Thankfully more than just warm water is needed for hurricane development…much more!!

Okay, enough on the temperatures. So, we are currently ENSO Neutral and will probably be neutral possibly through summer. What does that mean for the Hurricane season?

Looking at the left-hand side of the figure below, we see the average number of hurricane landfalls per year per region. The top most bar graph is the East Coast region followed by Florida, the Gulf Coast, and All Regions. Looking at the third chart down, the Gulf Coast, the La Nina (Cold) events produce nearly 1 hurricane landfall on the Gulf Coast (0.92). Then for Neutral ENSO years, the average falls to 0.74, which is still a high average. That is, statistically, three landfalls on the Gulf Coast out of four Neutral years. Then it drops to 0.52 in El Nino (warm) years.

Link to article: 063.1

Clearly El Nino reduces hurricane activity as shown by the last chart in the series for All Regions. However, the difference between Cold (La Nina) and Neutral is fairly small.

The point I want to make here is that we are coming out of a Cold Phase and transitioning into Neutral phase before transitioning into an El Nino phase late summer or fall. Many people hear El Nino and think that there is going to be a security blanket of sorts draped across the Gulf Coast to prevent hurricanes, but we know this is not the case at all. In fact, three out of the top five costliest hurricanes ever occurred in ENSO Neutral years and we will likely be in the Neutral mode for a good part of the hurricane season.

I'm not going to sit here and mock Mother Nature and try to predict the number of storms we will have and where they will make landfall, because in the one knows what the season will look like in terms of landfall locations along the US, if any, and number of storms. Statistically though, the gulf coast has only a slightly lower chance of seeing a landfall this year as it did last year. Last year only two tropical systems made landfall along the gulf coast; Don as a tropical depression on the lower Texas coast and tropical storm Lee in Louisiana. Of course, last year Texas was also dominated by high pressure that kept all tropical storms weak and far away for the most port. Unfortunately, the ensuing drought was terrible.

We shall see what this season has in store. Best to stay prepared.

I'll keep this going as the season nears and as updates are made to the outlooks and such. I'll also be tracking and updating on storms as they happen.

Thanks for reading!

Gulf Coast Tropics 2012 Hurricane Season Tropics Hurricane

Updated: 9:09 PM GMT on April 19, 2012


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

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About LPerezIII

I have a passion for Mother Nature's fury, serenity, and beauty. I express my soul through my music and photography. B.S. in Meteorology from TX A&M.

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