The effects of exposure to sewer gas are:
* Hydrogen sulfide poisoning. Exposure to low levels of hydrogen sulfide causes irritation of the eyes and respiratory tract. Other symptoms include nervousness, dizziness, nausea, headache, and drowsiness. This gas smells like rotten eggs, even at extremely low concentrations. Exposure to high concentrations can interfere with the sense of smell, making this warning signal unreliable. At extremely high levels, hydrogen sulfide can cause immediate loss of consciousness and death.
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Asphyxiation. Methane acts like carbon monoxide, blocking oxygen in the blood, and can similarly cause suffocation and death at high levels. Exposure to lower levels can produce flu-like symptoms such as headache, nausea, and drowsiness. Breathing undiluted sewer gas, even for short periods, as in a municipal sewer line or a manure storage tank, can result in suffocation and death. Sewer gas diffuses and mixes into indoor air, and will be most concentrated where it is entering. It can accumulate in basements.
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Explosion and fire. Methane and hydrogen sulfide are flammable and highly explosive.
Depending on the amount of sewer gas you were exposed to is the mitigating factor.
I am wondering if you have had any problems with your ears as that is more often than not the root cause of dizziness.
If you notice the dizziness has subsided or ended now that the sewer gas problem has been eliminated, it could have been the cause.
If the symptoms persist, consult an ENT (ear, nose and throat specialist).